net/sched: Add module aliases for cls_,sch_,act_ modules

No functional change intended, aliases will be used in followup commits.
Note for backporters: you may need to add aliases also for modules that
are already removed in mainline kernel but still in your version.

Patches were generated with the help of Coccinelle scripts like:

cat >scripts/coccinelle/misc/tcf_alias.cocci <<EOD
virtual patch
virtual report

@ haskernel @
@@

@ tcf_has_kind depends on report && haskernel @
identifier ops;
constant K;
@@

static struct tcf_proto_ops ops = {
.kind = K,
...
};
+char module_alias = K;
EOD

/usr/bin/spatch -D report --cocci-file scripts/coccinelle/misc/tcf_alias.cocci \
--dir . \
-I ./arch/x86/include -I ./arch/x86/include/generated -I ./include \
-I ./arch/x86/include/uapi -I ./arch/x86/include/generated/uapi \
-I ./include/uapi -I ./include/generated/uapi \
--include ./include/linux/compiler-version.h --include ./include/linux/kconfig.h \
--jobs 8 --chunksize 1 2>/dev/null | \
sed 's/char module_alias = "\([^"]*\)";/MODULE_ALIAS_NET_CLS("\1");/'

And analogously for:

static struct tc_action_ops ops = {
.kind = K,

static struct Qdisc_ops ops = {
.id = K,

(Someone familiar would be able to fit those into one .cocci file
without sed post processing.)

Signed-off-by: Michal Koutný <mkoutny@suse.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20240201130943.19536-3-mkoutny@suse.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net_sched: sch_fq: better validate TCA_FQ_WEIGHTS and TCA_FQ_PRIOMAP

syzbot was able to trigger the following report while providing
too small TCA_FQ_WEIGHTS attribute [1]

Fix is to use NLA_POLICY_EXACT_LEN() to ensure user space
provided correct sizes.

Apply the same fix to TCA_FQ_PRIOMAP.

[1]
BUG: KMSAN: uninit-value in fq_load_weights net/sched/sch_fq.c:960 [inline]
BUG: KMSAN: uninit-value in fq_change+0x1348/0x2fe0 net/sched/sch_fq.c:1071
fq_load_weights net/sched/sch_fq.c:960 [inline]
fq_change+0x1348/0x2fe0 net/sched/sch_fq.c:1071
fq_init+0x68e/0x780 net/sched/sch_fq.c:1159
qdisc_create+0x12f3/0x1be0 net/sched/sch_api.c:1326
tc_modify_qdisc+0x11ef/0x2c20
rtnetlink_rcv_msg+0x16a6/0x1840 net/core/rtnetlink.c:6558
netlink_rcv_skb+0x371/0x650 net/netlink/af_netlink.c:2545
rtnetlink_rcv+0x34/0x40 net/core/rtnetlink.c:6576
netlink_unicast_kernel net/netlink/af_netlink.c:1342 [inline]
netlink_unicast+0xf47/0x1250 net/netlink/af_netlink.c:1368
netlink_sendmsg+0x1238/0x13d0 net/netlink/af_netlink.c:1910
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
____sys_sendmsg+0x9c2/0xd60 net/socket.c:2588
___sys_sendmsg+0x28d/0x3c0 net/socket.c:2642
__sys_sendmsg net/socket.c:2671 [inline]
__do_sys_sendmsg net/socket.c:2680 [inline]
__se_sys_sendmsg net/socket.c:2678 [inline]
__x64_sys_sendmsg+0x307/0x490 net/socket.c:2678
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

Uninit was created at:
slab_post_alloc_hook+0x129/0xa70 mm/slab.h:768
slab_alloc_node mm/slub.c:3478 [inline]
kmem_cache_alloc_node+0x5e9/0xb10 mm/slub.c:3523
kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:560
__alloc_skb+0x318/0x740 net/core/skbuff.c:651
alloc_skb include/linux/skbuff.h:1286 [inline]
netlink_alloc_large_skb net/netlink/af_netlink.c:1214 [inline]
netlink_sendmsg+0xb34/0x13d0 net/netlink/af_netlink.c:1885
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
____sys_sendmsg+0x9c2/0xd60 net/socket.c:2588
___sys_sendmsg+0x28d/0x3c0 net/socket.c:2642
__sys_sendmsg net/socket.c:2671 [inline]
__do_sys_sendmsg net/socket.c:2680 [inline]
__se_sys_sendmsg net/socket.c:2678 [inline]
__x64_sys_sendmsg+0x307/0x490 net/socket.c:2678
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

CPU: 1 PID: 5001 Comm: syz-executor300 Not tainted 6.6.0-syzkaller-12401-g8f6f76a6a29f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023

Fixes: 29f834aa326e ("net_sched: sch_fq: add 3 bands and WRR scheduling")
Fixes: 49e7265fd098 ("net_sched: sch_fq: add TCA_FQ_WEIGHTS attribute")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Jamal Hadi Salim<jhs@mojatatu.com>
Link: https://lore.kernel.org/r/20231107160440.1992526-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

netlink: make range pointers in policies const

struct nla_policy is usually constant itself, but unless
we make the ranges inside constant we won't be able to
make range structs const. The ranges are not modified
by the core.

Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20231025162204.132528-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net_sched: sch_fq: fastpath needs to take care of sk->sk_pacing_status

If packets of a TCP flows take the fast path, we need to make sure
sk->sk_pacing_status is set to SK_PACING_FQ otherwise TCP might
fallback to internal pacing, which is not optimal.

Fixes: 076433bd78d7 ("net_sched: sch_fq: add fast path for mostly idle qdisc")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20231020201254.732527-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net_sched: sch_fq: fix off-by-one error in fq_dequeue()

A last minute change went wrong.

We need to look for a packet in all 3 bands, not only two.

Fixes: 29f834aa326e ("net_sched: sch_fq: add 3 bands and WRR scheduling")
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202310201422.a22b0999-oliver.sang@intel.com
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Cc: Dave Taht <dave.taht@gmail.com>
Cc: Toke Høiland-Jørgensen <toke@redhat.com>
Tested-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20231020200053.675951-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net_sched: sch_fq: add TCA_FQ_WEIGHTS attribute

This attribute can be used to tune the per band weight
and report them in "tc qdisc show" output:

qdisc fq 802f: parent 1:9 limit 100000p flow_limit 500p buckets 1024 orphan_mask 1023
quantum 8364b initial_quantum 41820b low_rate_threshold 550Kbit
refill_delay 40ms timer_slack 10us horizon 10s horizon_drop
bands 3 priomap 1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1 weights 589824 196608 65536
Sent 236460814 bytes 792991 pkt (dropped 0, overlimits 0 requeues 0)
rate 25816bit 10pps backlog 0b 0p requeues 0
flows 4 (inactive 4 throttled 0)
gc 0 throttled 19 latency 17.6us fastpath 773882

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Dave Taht <dave.taht@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net_sched: sch_fq: add 3 bands and WRR scheduling

Before Google adopted FQ for its production servers,
we had to ensure AF4 packets would get a higher share
than BE1 ones.

As discussed this week in Netconf 2023 in Paris, it is time
to upstream this for public use.

After this patch FQ can replace pfifo_fast, with the following
differences :

- FQ uses WRR instead of strict prio, to avoid starvation of
low priority packets.

- We make sure each band/prio tracks its own usage against sch->limit.
This was done to make sure flood of low priority packets would not
prevent AF4 packets to be queued. Contributed by Willem.

- priomap can be changed, if needed (default value are the ones
coming from pfifo_fast).

In this patch, we set default band weights so that :

- high prio (band=0) packets get 90% of the bandwidth
if they compete with low prio (band=2) packets.

- high prio packets get 75% of the bandwidth
if they compete with medium prio (band=1) packets.

Following patch in this series adds the possibility to tune
the per-band weights.

As we added many fields in 'struct fq_sched_data', we had
to make sure to have the first cache line read-mostly, and
avoid wasting precious cache lines.

More optimizations are possible but will be sent separately.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Dave Taht <dave.taht@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net_sched: sch_fq: remove q->ktime_cache

Now that both enqueue() and dequeue() need to use ktime_get_ns(),
there is no point wasting 8 bytes in struct fq_sched_data.

This makes room for future fields. ;)

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Dave Taht <dave.taht@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net: implement lockless SO_MAX_PACING_RATE

SO_MAX_PACING_RATE setsockopt() does not need to hold
the socket lock, because sk->sk_pacing_rate readers
can run fine if the value is changed by other threads,
after adding READ_ONCE() accessors.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: always garbage collect

FQ performs garbage collection at enqueue time, and only
if number of flows is above a given threshold, which
is hit after the qdisc has been used a bit.

Since an RB-tree traversal is needed to locate a flow,
it makes sense to perform gc all the time, to keep
rb-trees smaller.

This reduces by 50 % average storage costs in FQ,
and avoids 1 cache line miss at enqueue time when
fast path added in prior patch can not be used.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: add fast path for mostly idle qdisc

TCQ_F_CAN_BYPASS can be used by few qdiscs.

Idea is that if we queue a packet to an empty qdisc,
following dequeue() would pick it immediately.

FQ can not use the generic TCQ_F_CAN_BYPASS code,
because some additional checks need to be performed.

This patch adds a similar fast path to FQ.

Most of the time, qdisc is not throttled,
and many packets can avoid bringing/touching
at least four cache lines, and consuming 128bytes
of memory to store the state of a flow.

After this patch, netperf can send UDP packets about 13 % faster,
and pktgen goes 30 % faster (when FQ is in the way), on a fast NIC.

TCP traffic is also improved, thanks to a reduction of cache line misses.
I have measured a 5 % increase of throughput on a tcp_rr intensive workload.

tc -s -d qd sh dev eth1
...
qdisc fq 8004: parent 1:2 limit 10000p flow_limit 100p buckets 1024
orphan_mask 1023 quantum 3028b initial_quantum 15140b low_rate_threshold 550Kbit
refill_delay 40ms timer_slack 10us horizon 10s horizon_drop
Sent 5646784384 bytes 1985161 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
flows 122 (inactive 122 throttled 0)
gc 0 highprio 0 fastpath 659990 throttled 27762 latency 8.57us

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: change how @inactive is tracked

Currently, when one fq qdisc has no more packets to send, it can still
have some flows stored in its RR lists (q->new_flows & q->old_flows)

This was a design choice, but what is a bit disturbing is that
the inactive_flows counter does not include the count of empty flows
in RR lists.

As next patch needs to know better if there are active flows,
this change makes inactive_flows exact.

Before the patch, following command on an empty qdisc could have returned:

lpaa17:~# tc -s -d qd sh dev eth1 | grep inactive
flows 1322 (inactive 1316 throttled 0)
flows 1330 (inactive 1325 throttled 0)
flows 1193 (inactive 1190 throttled 0)
flows 1208 (inactive 1202 throttled 0)

After the patch, we now have:

lpaa17:~# tc -s -d qd sh dev eth1 | grep inactive
flows 1322 (inactive 1322 throttled 0)
flows 1330 (inactive 1330 throttled 0)
flows 1193 (inactive 1193 throttled 0)
flows 1208 (inactive 1208 throttled 0)

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: struct sched_data reorg

q->flows can be often modified, and q->timer_slack is read mostly.

Exchange the two fields, so that cache line countaining
quantum, initial_quantum, and other critical parameters
stay clean (read-mostly).

Move q->watchdog next to q->stat_throttled

Add comments explaining how the structure is split in
three different parts.

pahole output before the patch:

struct fq_sched_data {
struct fq_flow_head new_flows; /* 0 0x10 */
struct fq_flow_head old_flows; /* 0x10 0x10 */
struct rb_root delayed; /* 0x20 0x8 */
u64 time_next_delayed_flow; /* 0x28 0x8 */
u64 ktime_cache; /* 0x30 0x8 */
unsigned long unthrottle_latency_ns; /* 0x38 0x8 */
/* --- cacheline 1 boundary (64 bytes) --- */
struct fq_flow internal __attribute__((__aligned__(64))); /* 0x40 0x80 */

/* XXX last struct has 16 bytes of padding */

/* --- cacheline 3 boundary (192 bytes) --- */
u32 quantum; /* 0xc0 0x4 */
u32 initial_quantum; /* 0xc4 0x4 */
u32 flow_refill_delay; /* 0xc8 0x4 */
u32 flow_plimit; /* 0xcc 0x4 */
unsigned long flow_max_rate; /* 0xd0 0x8 */
u64 ce_threshold; /* 0xd8 0x8 */
u64 horizon; /* 0xe0 0x8 */
u32 orphan_mask; /* 0xe8 0x4 */
u32 low_rate_threshold; /* 0xec 0x4 */
struct rb_root * fq_root; /* 0xf0 0x8 */
u8 rate_enable; /* 0xf8 0x1 */
u8 fq_trees_log; /* 0xf9 0x1 */
u8 horizon_drop; /* 0xfa 0x1 */

/* XXX 1 byte hole, try to pack */

<bad> u32 flows; /* 0xfc 0x4 */
/* --- cacheline 4 boundary (256 bytes) --- */
u32 inactive_flows; /* 0x100 0x4 */
u32 throttled_flows; /* 0x104 0x4 */
u64 stat_gc_flows; /* 0x108 0x8 */
u64 stat_internal_packets; /* 0x110 0x8 */
u64 stat_throttled; /* 0x118 0x8 */
u64 stat_ce_mark; /* 0x120 0x8 */
u64 stat_horizon_drops; /* 0x128 0x8 */
u64 stat_horizon_caps; /* 0x130 0x8 */
u64 stat_flows_plimit; /* 0x138 0x8 */
/* --- cacheline 5 boundary (320 bytes) --- */
u64 stat_pkts_too_long; /* 0x140 0x8 */
u64 stat_allocation_errors; /* 0x148 0x8 */
<bad> u32 timer_slack; /* 0x150 0x4 */

/* XXX 4 bytes hole, try to pack */

struct qdisc_watchdog watchdog; /* 0x158 0x48 */

/* size: 448, cachelines: 7, members: 34 */
/* sum members: 411, holes: 2, sum holes: 5 */
/* padding: 32 */
/* paddings: 1, sum paddings: 16 */
/* forced alignments: 1 */
};

pahole output after the patch:

struct fq_sched_data {
struct fq_flow_head new_flows; /* 0 0x10 */
struct fq_flow_head old_flows; /* 0x10 0x10 */
struct rb_root delayed; /* 0x20 0x8 */
u64 time_next_delayed_flow; /* 0x28 0x8 */
u64 ktime_cache; /* 0x30 0x8 */
unsigned long unthrottle_latency_ns; /* 0x38 0x8 */
/* --- cacheline 1 boundary (64 bytes) --- */
struct fq_flow internal __attribute__((__aligned__(64))); /* 0x40 0x80 */

/* XXX last struct has 16 bytes of padding */

/* --- cacheline 3 boundary (192 bytes) --- */
u32 quantum; /* 0xc0 0x4 */
u32 initial_quantum; /* 0xc4 0x4 */
u32 flow_refill_delay; /* 0xc8 0x4 */
u32 flow_plimit; /* 0xcc 0x4 */
unsigned long flow_max_rate; /* 0xd0 0x8 */
u64 ce_threshold; /* 0xd8 0x8 */
u64 horizon; /* 0xe0 0x8 */
u32 orphan_mask; /* 0xe8 0x4 */
u32 low_rate_threshold; /* 0xec 0x4 */
struct rb_root * fq_root; /* 0xf0 0x8 */
u8 rate_enable; /* 0xf8 0x1 */
u8 fq_trees_log; /* 0xf9 0x1 */
u8 horizon_drop; /* 0xfa 0x1 */

/* XXX 1 byte hole, try to pack */

<good> u32 timer_slack; /* 0xfc 0x4 */
/* --- cacheline 4 boundary (256 bytes) --- */
<good> u32 flows; /* 0x100 0x4 */
u32 inactive_flows; /* 0x104 0x4 */
u32 throttled_flows; /* 0x108 0x4 */

/* XXX 4 bytes hole, try to pack */

u64 stat_throttled; /* 0x110 0x8 */
<better> struct qdisc_watchdog watchdog; /* 0x118 0x48 */
/* --- cacheline 5 boundary (320 bytes) was 32 bytes ago --- */
u64 stat_gc_flows; /* 0x160 0x8 */
u64 stat_internal_packets; /* 0x168 0x8 */
u64 stat_ce_mark; /* 0x170 0x8 */
u64 stat_horizon_drops; /* 0x178 0x8 */
/* --- cacheline 6 boundary (384 bytes) --- */
u64 stat_horizon_caps; /* 0x180 0x8 */
u64 stat_flows_plimit; /* 0x188 0x8 */
u64 stat_pkts_too_long; /* 0x190 0x8 */
u64 stat_allocation_errors; /* 0x198 0x8 */

/* Force padding: */
u64 :64;
u64 :64;
u64 :64;
u64 :64;

/* size: 448, cachelines: 7, members: 34 */
/* sum members: 411, holes: 2, sum holes: 5 */
/* padding: 32 */
/* paddings: 1, sum paddings: 16 */
/* forced alignments: 1 */
};

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched: sch_fq: fix integer overflow of "credit"

if sch_fq is configured with "initial quantum" having values greater than
INT_MAX, the first assignment of "credit" does signed integer overflow to
a very negative value.
In this situation, the syzkaller script provided by Cristoph triggers the
CPU soft-lockup warning even with few sockets. It's not an infinite loop,
but "credit" wasn't probably meant to be minus 2Gb for each new flow.
Capping "initial quantum" to INT_MAX proved to fix the issue.

v2: validation of "initial quantum" is done in fq_policy, instead of open
coding in fq_change() _ suggested by Jakub Kicinski

Reported-by: Christoph Paasch <cpaasch@apple.com>
Link: https://github.com/multipath-tcp/mptcp_net-next/issues/377
Fixes: afe4fd062416 ("pkt_sched: fq: Fair Queue packet scheduler")
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Link: https://lore.kernel.org/r/7b3a3c7e36d03068707a021760a194a8eb5ad41a.1682002300.git.dcaratti@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: sched: remove redundant NULL check in change hook function

Currently, the change function can be called by two ways. The one way is
that qdisc_change() will call it. Before calling change function,
qdisc_change() ensures tca[TCA_OPTIONS] is not empty. The other way is
that .init() will call it. The opt parameter is also checked before
calling change function in .init(). Therefore, it's no need to check the
input parameter opt in change function.

Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Link: https://lore.kernel.org/r/20220829071219.208646-1-shaozhengchao@huawei.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Revert "net: sched: Pass root lock to Qdisc_ops.enqueue"

This reverts commit aebe4426ccaa4838f36ea805cdf7d76503e65117.

Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: sched: Pass root lock to Qdisc_ops.enqueue

A following patch introduces qevents, points in qdisc algorithm where
packet can be processed by user-defined filters. Should this processing
lead to a situation where a new packet is to be enqueued on the same port,
holding the root lock would lead to deadlocks. To solve the issue, qevent
handler needs to unlock and relock the root lock when necessary.

To that end, add the root lock argument to the qdisc op enqueue, and
propagate throughout.

Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: Add MODULE_DESCRIPTION entries to network modules

The user tool modinfo is used to get information on kernel modules, including a
description where it is available.

This patch adds a brief MODULE_DESCRIPTION to the following modules:

9p
drop_monitor
esp4_offload
esp6_offload
fou
fou6
ila
sch_fq
sch_fq_codel
sch_hhf

Signed-off-by: Rob Gill <rrobgill@protonmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: add horizon attribute

QUIC servers would like to use SO_TXTIME, without having CAP_NET_ADMIN,
to efficiently pace UDP packets.

As far as sch_fq is concerned, we need to add safety checks, so
that a buggy application does not fill the qdisc with packets
having delivery time far in the future.

This patch adds a configurable horizon (default: 10 seconds),
and a configurable policy when a packet is beyond the horizon
at enqueue() time:
- either drop the packet (default policy)
- or cap its delivery time to the horizon.

$ tc -s -d qd sh dev eth0
qdisc fq 8022: root refcnt 257 limit 10000p flow_limit 100p buckets 1024
orphan_mask 1023 quantum 10Kb initial_quantum 51160b low_rate_threshold 550Kbit
refill_delay 40.0ms timer_slack 10.000us horizon 10.000s
Sent 1234215879 bytes 837099 pkt (dropped 21, overlimits 0 requeues 6)
backlog 0b 0p requeues 6
flows 1191 (inactive 1177 throttled 0)
gc 0 highprio 0 throttled 692 latency 11.480us
pkts_too_long 0 alloc_errors 0 horizon_drops 21 horizon_caps 0

v2: fixed an overflow on 32bit kernels in fq_init(), reported
by kbuild test robot <lkp@intel.com>

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: perform a prefetch() earlier

The prefetch() done in fq_dequeue() can be done a bit earlier
after the refactoring of the code done in the prior patch.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: do not call fq_peek() twice per packet

This refactors the code to not call fq_peek() from fq_dequeue_head()
since the caller can provide the skb.

Also rename fq_dequeue_head() to fq_dequeue_skb() because 'head' is
a bit vague, given the skb could come from t_root rb-tree.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: use bulk freeing in fq_gc()

fq_gc() already builds a small array of pointers, so using
kmem_cache_free_bulk() needs very little change.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: change fq_flow size/layout

sizeof(struct fq_flow) is 112 bytes on 64bit arches.

This means that half of them use two cache lines, but 50% use
three cache lines.

This patch adds cache line alignment, and makes sure that only
the first cache line is touched by fq_enqueue(), which is more
expensive that fq_dequeue() in general.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: avoid touching f->next from fq_gc()

A significant amount of cpu cycles is spent in fq_gc()

When fq_gc() does its lookup in the rb-tree, it needs the
following fields from struct fq_flow :

f->sk (lookup key in the rb-tree)
f->fq_node (anchor in the rb-tree)
f->next (used to determine if the flow is detached)
f->age (used to determine if the flow is candidate for gc)

This unfortunately spans two cache lines (assuming 64 bytes cache lines)

We can avoid using f->next, if we use the low order bit of f->{age|tail}

This low order bit is 0, if f->tail points to an sk_buff.
We set the low order bit to 1, if the union contains a jiffies value.

Combined with the following patch, this makes sure we only need
to bring into cpu caches one cache line per flow.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: enable use of hrtimer slack

Add a new attribute to control the fq qdisc hrtimer slack.

Default is set to 10 usec.

When/if packets are throttled, fq set up an hrtimer that can
lead to one interrupt per packet in the throttled queue.

By using a timer slack, we allow better use of timer interrupts,
by giving them a chance to call multiple timer callbacks
at each hardware interrupt.

Also, giving a slack allows FQ to dequeue batches of packets
instead of a single one, thus increasing xmit_more efficiency.

This has no negative effect on the rate a TCP flow can sustain,
since each TCP flow maintains its own precise vtime (tp->tcp_wstamp_ns)

v2: added strict netlink checking (as feedback from Jakub Kicinski)

Tested:
1000 concurrent flows all using paced packets.
1,000,000 packets sent per second.

Before the patch :

$ vmstat 2 10
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
r b swpd free buff cache si so bi bo in cs us sy id wa st
0 0 0 60726784 23628 3485992 0 0 138 1 977 535 0 12 87 0 0
0 0 0 60714700 23628 3485628 0 0 0 0 1568827 26462 0 22 78 0 0
1 0 0 60716012 23628 3485656 0 0 0 0 1570034 26216 0 22 78 0 0
0 0 0 60722420 23628 3485492 0 0 0 0 1567230 26424 0 22 78 0 0
0 0 0 60727484 23628 3485556 0 0 0 0 1568220 26200 0 22 78 0 0
2 0 0 60718900 23628 3485380 0 0 0 40 1564721 26630 0 22 78 0 0
2 0 0 60718096 23628 3485332 0 0 0 0 1562593 26432 0 22 78 0 0
0 0 0 60719608 23628 3485064 0 0 0 0 1563806 26238 0 22 78 0 0
1 0 0 60722876 23628 3485236 0 0 0 130 1565874 26566 0 22 78 0 0
1 0 0 60722752 23628 3484908 0 0 0 0 1567646 26247 0 22 78 0 0

After the patch, slack of 10 usec, we can see a reduction of interrupts
per second, and a small decrease of reported cpu usage.

$ vmstat 2 10
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
r b swpd free buff cache si so bi bo in cs us sy id wa st
1 0 0 60722564 23628 3484728 0 0 133 1 696 545 0 13 87 0 0
1 0 0 60722568 23628 3484824 0 0 0 0 977278 25469 0 20 80 0 0
0 0 0 60716396 23628 3484764 0 0 0 0 979997 25326 0 20 80 0 0
0 0 0 60713844 23628 3484960 0 0 0 0 981394 25249 0 20 80 0 0
2 0 0 60720468 23628 3484916 0 0 0 0 982860 25062 0 20 80 0 0
1 0 0 60721236 23628 3484856 0 0 0 0 982867 25100 0 20 80 0 0
1 0 0 60722400 23628 3484456 0 0 0 8 982698 25303 0 20 80 0 0
0 0 0 60715396 23628 3484428 0 0 0 0 981777 25176 0 20 80 0 0
0 0 0 60716520 23628 3486544 0 0 0 36 978965 27857 0 21 79 0 0
0 0 0 60719592 23628 3486516 0 0 0 22 977318 25106 0 20 80 0 0

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: fq: add missing attribute validation for orphan mask

Add missing attribute validation for TCA_FQ_ORPHAN_MASK
to the netlink policy.

Fixes: 06eb395fa985 ("pkt_sched: fq: better control of DDOS traffic")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

pkt_sched: fq: do not accept silly TCA_FQ_QUANTUM

As diagnosed by Florian :

If TCA_FQ_QUANTUM is set to 0x80000000, fq_deueue()
can loop forever in :

if (f->credit <= 0) {
f->credit += q->quantum;
goto begin;
}

... because f->credit is either 0 or -2147483648.

Let's limit TCA_FQ_QUANTUM to no more than 1 << 20 :
This max value should limit risks of breaking user setups
while fixing this bug.

Fixes: afe4fd062416 ("pkt_sched: fq: Fair Queue packet scheduler")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Diagnosed-by: Florian Westphal <fw@strlen.de>
Reported-by: syzbot+dc9071cc5a85950bdfce@syzkaller.appspotmail.com
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: properly set sk->sk_pacing_status

If fq_classify() recycles a struct fq_flow because
a socket structure has been reallocated, we do not
set sk->sk_pacing_status immediately, but later if the
flow becomes detached.

This means that any flow requiring pacing (BBR, or SO_MAX_PACING_RATE)
might fallback to TCP internal pacing, which requires a per-socket
high resolution timer, and therefore more cpu cycles.

Fixes: 218af599fa63 ("tcp: internal implementation for pacing")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: remove one obsolete check in fq_dequeue()

After commit eeb84aa0d0aff ("net_sched: sch_fq: do not assume EDT
packets are ordered"), all skbs get a non zero time_to_send
in flow_queue_add()

This means @time_next_packet variable in fq_dequeue()
can no longer be zero.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

net_sched: sch_fq: handle non connected flows

FQ packet scheduler assumed that packets could be classified
based on their owning socket.

This means that if a UDP server uses one UDP socket to send
packets to different destinations, packets all land
in one FQ flow.

This is unfair, since each TCP flow has a unique bucket, meaning
that in case of pressure (fully utilised uplink), TCP flows
have more share of the bandwidth.

If we instead detect unconnected sockets, we can use a stochastic
hash based on the 4-tuple hash.

This also means a QUIC server using one UDP socket will properly
spread the outgoing packets to different buckets, and in-kernel
pacing based on EDT model will no longer risk having big rb-tree on
one flow.

Note that UDP application might provide the skb->hash in an
ancillary message at sendmsg() time to avoid the cost of a dissection
in fq packet scheduler.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: do not assume EDT packets are ordered

TCP stack makes sure packets for a given flow are monotically
increasing, but we want to allow UDP packets to use EDT as
well, so that QUIC servers can use in-kernel pacing.

This patch adds a per-flow rb-tree on which packets might
be stored. We still try to use the linear list for the
typical cases where packets are queued with monotically
increasing skb->tstamp, since queue/dequeue packets on
a standard list is O(1).

Note that the ability to store packets in arbitrary EDT
order will allow us to implement later a per TCP socket
mechanism adding delays (with jitter eventually) and reorders,
to implement convenient network emulators.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

netlink: make validation more configurable for future strictness

We currently have two levels of strict validation:

1) liberal (default)
- undefined (type >= max) & NLA_UNSPEC attributes accepted
- attribute length >= expected accepted
- garbage at end of message accepted
2) strict (opt-in)
- NLA_UNSPEC attributes accepted
- attribute length >= expected accepted

Split out parsing strictness into four different options:
* TRAILING - check that there's no trailing data after parsing
attributes (in message or nested)
* MAXTYPE - reject attrs > max known type
* UNSPEC - reject attributes with NLA_UNSPEC policy entries
* STRICT_ATTRS - strictly validate attribute size

The default for future things should be *everything*.
The current *_strict() is a combination of TRAILING and MAXTYPE,
and is renamed to _deprecated_strict().
The current regular parsing has none of this, and is renamed to
*_parse_deprecated().

Additionally it allows us to selectively set one of the new flags
even on old policies. Notably, the UNSPEC flag could be useful in
this case, since it can be arranged (by filling in the policy) to
not be an incompatible userspace ABI change, but would then going
forward prevent forgetting attribute entries. Similar can apply
to the POLICY flag.

We end up with the following renames:
* nla_parse -> nla_parse_deprecated
* nla_parse_strict -> nla_parse_deprecated_strict
* nlmsg_parse -> nlmsg_parse_deprecated
* nlmsg_parse_strict -> nlmsg_parse_deprecated_strict
* nla_parse_nested -> nla_parse_nested_deprecated
* nla_validate_nested -> nla_validate_nested_deprecated

Using spatch, of course:
@@
expression TB, MAX, HEAD, LEN, POL, EXT;
@@
-nla_parse(TB, MAX, HEAD, LEN, POL, EXT)
+nla_parse_deprecated(TB, MAX, HEAD, LEN, POL, EXT)

@@
expression NLH, HDRLEN, TB, MAX, POL, EXT;
@@
-nlmsg_parse(NLH, HDRLEN, TB, MAX, POL, EXT)
+nlmsg_parse_deprecated(NLH, HDRLEN, TB, MAX, POL, EXT)

@@
expression NLH, HDRLEN, TB, MAX, POL, EXT;
@@
-nlmsg_parse_strict(NLH, HDRLEN, TB, MAX, POL, EXT)
+nlmsg_parse_deprecated_strict(NLH, HDRLEN, TB, MAX, POL, EXT)

@@
expression TB, MAX, NLA, POL, EXT;
@@
-nla_parse_nested(TB, MAX, NLA, POL, EXT)
+nla_parse_nested_deprecated(TB, MAX, NLA, POL, EXT)

@@
expression START, MAX, POL, EXT;
@@
-nla_validate_nested(START, MAX, POL, EXT)
+nla_validate_nested_deprecated(START, MAX, POL, EXT)

@@
expression NLH, HDRLEN, MAX, POL, EXT;
@@
-nlmsg_validate(NLH, HDRLEN, MAX, POL, EXT)
+nlmsg_validate_deprecated(NLH, HDRLEN, MAX, POL, EXT)

For this patch, don't actually add the strict, non-renamed versions
yet so that it breaks compile if I get it wrong.

Also, while at it, make nla_validate and nla_parse go down to a
common __nla_validate_parse() function to avoid code duplication.

Ultimately, this allows us to have very strict validation for every
new caller of nla_parse()/nlmsg_parse() etc as re-introduced in the
next patch, while existing things will continue to work as is.

In effect then, this adds fully strict validation for any new command.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

netlink: make nla_nest_start() add NLA_F_NESTED flag

Even if the NLA_F_NESTED flag was introduced more than 11 years ago, most
netlink based interfaces (including recently added ones) are still not
setting it in kernel generated messages. Without the flag, message parsers
not aware of attribute semantics (e.g. wireshark dissector or libmnl's
mnl_nlmsg_fprintf()) cannot recognize nested attributes and won't display
the structure of their contents.

Unfortunately we cannot just add the flag everywhere as there may be
userspace applications which check nlattr::nla_type directly rather than
through a helper masking out the flags. Therefore the patch renames
nla_nest_start() to nla_nest_start_noflag() and introduces nla_nest_start()
as a wrapper adding NLA_F_NESTED. The calls which add NLA_F_NESTED manually
are rewritten to use nla_nest_start().

Except for changes in include/net/netlink.h, the patch was generated using
this semantic patch:

@@ expression E1, E2; @@
-nla_nest_start(E1, E2)
+nla_nest_start_noflag(E1, E2)

@@ expression E1, E2; @@
-nla_nest_start_noflag(E1, E2 | NLA_F_NESTED)
+nla_nest_start(E1, E2)

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: avoid calling ktime_get_ns() if not needed

There are two cases were we can avoid calling ktime_get_ns() :

1) Queue is empty.
2) Internal queue is not empty.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: ensure maxrate fq parameter applies to EDT flows

When EDT conversion happened, fq lost the ability to enfore a maxrate
for all flows. It kept it for non EDT flows.

This commit restores the functionality.

Tested:

tc qd replace dev eth0 root fq maxrate 500Mbit
netperf -P0 -H host -- -O THROUGHPUT
489.75

Fixes: ab408b6dc744 ("tcp: switch tcp and sch_fq to new earliest departure time model")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: add dctcp-like marking

Similar to 80ba92fa1a92 ("codel: add ce_threshold attribute")

After EDT adoption, it became easier to implement DCTCP-like CE marking.

In many cases, queues are not building in the network fabric but on
the hosts themselves.

If packets leaving fq missed their Earliest Departure Time by XXX usec,
we mark them with ECN CE. This gives a feedback (after one RTT) to
the sender to slow down and find better operating mode.

Example :

tc qd replace dev eth0 root fq ce_threshold 2.5ms

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: no longer use skb_is_tcp_pure_ack()

With the new EDT model, sch_fq no longer has to special
case TCP pure acks, since their skb->tstamp will allow them
being sent without pacing delay.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: extend sk_pacing_rate to unsigned long

sk_pacing_rate has beed introduced as a u32 field in 2013,
effectively limiting per flow pacing to 34Gbit.

We believe it is time to allow TCP to pace high speed flows
on 64bit hosts, as we now can reach 100Gbit on one TCP flow.

This patch adds no cost for 32bit kernels.

The tcpi_pacing_rate and tcpi_max_pacing_rate were already
exported as 64bit, so iproute2/ss command require no changes.

Unfortunately the SO_MAX_PACING_RATE socket option will stay
32bit and we will need to add a new option to let applications
control high pacing rates.

State Recv-Q Send-Q Local Address:Port Peer Address:Port
ESTAB 0 1787144 10.246.9.76:49992 10.246.9.77:36741
timer:(on,003ms,0) ino:91863 sk:2 <->
skmem:(r0,rb540000,t66440,tb2363904,f605944,w1822984,o0,bl0,d0)
ts sack bbr wscale:8,8 rto:201 rtt:0.057/0.006 mss:1448
rcvmss:536 advmss:1448
cwnd:138 ssthresh:178 bytes_acked:256699822585 segs_out:177279177
segs_in:3916318 data_segs_out:177279175
bbr:(bw:31276.8Mbps,mrtt:0,pacing_gain:1.25,cwnd_gain:2)
send 28045.5Mbps lastrcv:73333
pacing_rate 38705.0Mbps delivery_rate 22997.6Mbps
busy:73333ms unacked:135 retrans:0/157 rcv_space:14480
notsent:2085120 minrtt:0.013

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp/fq: move back to CLOCK_MONOTONIC

In the recent TCP/EDT patch series, I switched TCP and sch_fq
clocks from MONOTONIC to TAI, in order to meet the choice done
earlier for sch_etf packet scheduler.

But sure enough, this broke some setups were the TAI clock
jumps forward (by almost 50 year...), as reported
by Leonard Crestez.

If we want to converge later, we'll probably need to add
an skb field to differentiate the clock bases, or a socket option.

In the meantime, an UDP application will need to use CLOCK_MONOTONIC
base for its SCM_TXTIME timestamps if using fq packet scheduler.

Fixes: 72b0094f9182 ("tcp: switch tcp_clock_ns() to CLOCK_TAI base")
Fixes: 142537e41923 ("net_sched: sch_fq: switch to CLOCK_TAI")
Fixes: fd2bca2aa789 ("tcp: switch internal pacing timer to CLOCK_TAI")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Leonard Crestez <leonard.crestez@nxp.com>
Tested-by: Leonard Crestez <leonard.crestez@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: remove dead code dealing with retransmits

With the earliest departure time model, we no longer plan
special casing TCP retransmits. We therefore remove dead
code (since most compilers understood skb_is_retransmit()
was false)

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: switch tcp and sch_fq to new earliest departure time model

TCP keeps track of tcp_wstamp_ns by itself, meaning sch_fq
no longer has to do it.

Thanks to this model, TCP can get more accurate RTT samples,
since pacing no longer inflates them.

This has the nice effect of removing some delays caused by FQ
quantum mechanism, causing inflated max/P99 latencies.

Also we might relax TCP Small Queue tight limits in the future,
since this new model allow TCP to build bigger batches, since
sch_fq (or a device with earliest departure time offload) ensure
these packets will be delivered on time.

Note that other protocols are not converted (they will probably
never be) so sch_fq has still support for SO_MAX_PACING_RATE

Tested:

Test showing FQ pacing quantum artifact for low-rate flows,
adding unexpected throttles for RPC flows, inflating max and P99 latencies.

The parameters chosen here are to show what happens typically when
a TCP flow has a reduced pacing rate (this can be caused by a reduced
cwin after few losses, or/and rtt above few ms)

MIBS="MIN_LATENCY,MEAN_LATENCY,MAX_LATENCY,P99_LATENCY,STDDEV_LATENCY"
Before :
$ netperf -H 10.246.7.133 -t TCP_RR -Cc -T6,6 -- -q 2000000 -r 100,100 -o $MIBS
MIGRATED TCP REQUEST/RESPONSE TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 10.246.7.133 () port 0 AF_INET : first burst 0 : cpu bind
Minimum Latency Microseconds,Mean Latency Microseconds,Maximum Latency Microseconds,99th Percentile Latency Microseconds,Stddev Latency Microseconds
19,82.78,5279,3825,482.02

After :
$ netperf -H 10.246.7.133 -t TCP_RR -Cc -T6,6 -- -q 2000000 -r 100,100 -o $MIBS
MIGRATED TCP REQUEST/RESPONSE TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 10.246.7.133 () port 0 AF_INET : first burst 0 : cpu bind
Minimum Latency Microseconds,Mean Latency Microseconds,Maximum Latency Microseconds,99th Percentile Latency Microseconds,Stddev Latency Microseconds
20,49.94,128,63,3.18

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: switch to CLOCK_TAI

TCP will soon provide per skb->tstamp with earliest departure time,
so that sch_fq does not have to determine departure time by looking
at socket sk_pacing_rate.

We chose in linux-4.19 CLOCK_TAI as the clock base for transports,
qdiscs, and NIC offloads.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: Add and use skb_mark_not_on_list().

An SKB is not on a list if skb->next is NULL.

Codify this convention into a helper function and use it
where we are dequeueing an SKB and need to mark it as such.

Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: fq: take care of throttled flows before reuse

Normally, a socket can not be freed/reused unless all its TX packets
left qdisc and were TX-completed. However connect(AF_UNSPEC) allows
this to happen.

With commit fc59d5bdf1e3 ("pkt_sched: fq: clear time_next_packet for
reused flows") we cleared f->time_next_packet but took no special
action if the flow was still in the throttled rb-tree.

Since f->time_next_packet is the key used in the rb-tree searches,
blindly clearing it might break rb-tree integrity. We need to make
sure the flow is no longer in the rb-tree to avoid this problem.

Fixes: fc59d5bdf1e3 ("pkt_sched: fq: clear time_next_packet for reused flows")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: sched: sch: add extack for change qdisc ops

This patch adds extack support for change callback for qdisc ops
structtur to prepare per-qdisc specific changes for extack.

Cc: David Ahern <dsahern@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Alexander Aring <aring@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: sched: sch: add extack for init callback

This patch adds extack support for init callback to prepare per-qdisc
specific changes for extack.

Cc: David Ahern <dsahern@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Alexander Aring <aring@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

mm, tree wide: replace __GFP_REPEAT by __GFP_RETRY_MAYFAIL with more useful semantic

__GFP_REPEAT was designed to allow retry-but-eventually-fail semantic to
the page allocator. This has been true but only for allocations
requests larger than PAGE_ALLOC_COSTLY_ORDER. It has been always
ignored for smaller sizes. This is a bit unfortunate because there is
no way to express the same semantic for those requests and they are
considered too important to fail so they might end up looping in the
page allocator for ever, similarly to GFP_NOFAIL requests.

Now that the whole tree has been cleaned up and accidental or misled
usage of __GFP_REPEAT flag has been removed for !costly requests we can
give the original flag a better name and more importantly a more useful
semantic. Let's rename it to __GFP_RETRY_MAYFAIL which tells the user
that the allocator would try really hard but there is no promise of a
success. This will work independent of the order and overrides the
default allocator behavior. Page allocator users have several levels of
guarantee vs. cost options (take GFP_KERNEL as an example)

- GFP_KERNEL & ~__GFP_RECLAIM - optimistic allocation without _any_
attempt to free memory at all. The most light weight mode which even
doesn't kick the background reclaim. Should be used carefully because
it might deplete the memory and the next user might hit the more
aggressive reclaim

- GFP_KERNEL & ~__GFP_DIRECT_RECLAIM (or GFP_NOWAIT)- optimistic
allocation without any attempt to free memory from the current
context but can wake kswapd to reclaim memory if the zone is below
the low watermark. Can be used from either atomic contexts or when
the request is a performance optimization and there is another
fallback for a slow path.

- (GFP_KERNEL|__GFP_HIGH) & ~__GFP_DIRECT_RECLAIM (aka GFP_ATOMIC) -
non sleeping allocation with an expensive fallback so it can access
some portion of memory reserves. Usually used from interrupt/bh
context with an expensive slow path fallback.

- GFP_KERNEL - both background and direct reclaim are allowed and the
_default_ page allocator behavior is used. That means that !costly
allocation requests are basically nofail but there is no guarantee of
that behavior so failures have to be checked properly by callers
(e.g. OOM killer victim is allowed to fail currently).

- GFP_KERNEL | __GFP_NORETRY - overrides the default allocator behavior
and all allocation requests fail early rather than cause disruptive
reclaim (one round of reclaim in this implementation). The OOM killer
is not invoked.

- GFP_KERNEL | __GFP_RETRY_MAYFAIL - overrides the default allocator
behavior and all allocation requests try really hard. The request
will fail if the reclaim cannot make any progress. The OOM killer
won't be triggered.

- GFP_KERNEL | __GFP_NOFAIL - overrides the default allocator behavior
and all allocation requests will loop endlessly until they succeed.
This might be really dangerous especially for larger orders.

Existing users of __GFP_REPEAT are changed to __GFP_RETRY_MAYFAIL
because they already had their semantic. No new users are added.
__alloc_pages_slowpath is changed to bail out for __GFP_RETRY_MAYFAIL if
there is no progress and we have already passed the OOM point.

This means that all the reclaim opportunities have been exhausted except
the most disruptive one (the OOM killer) and a user defined fallback
behavior is more sensible than keep retrying in the page allocator.

[akpm@linux-foundation.org: fix arch/sparc/kernel/mdesc.c]
[mhocko@suse.com: semantic fix]
Link: http://lkml.kernel.org/r/20170626123847.GM11534@dhcp22.suse.cz
[mhocko@kernel.org: address other thing spotted by Vlastimil]
Link: http://lkml.kernel.org/r/20170626124233.GN11534@dhcp22.suse.cz
Link: http://lkml.kernel.org/r/20170623085345.11304-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Alex Belits <alex.belits@cavium.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: NeilBrown <neilb@suse.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

tcp: internal implementation for pacing

BBR congestion control depends on pacing, and pacing is
currently handled by sch_fq packet scheduler for performance reasons,
and also because implemening pacing with FQ was convenient to truly
avoid bursts.

However there are many cases where this packet scheduler constraint
is not practical.
- Many linux hosts are not focusing on handling thousands of TCP
flows in the most efficient way.
- Some routers use fq_codel or other AQM, but still would like
to use BBR for the few TCP flows they initiate/terminate.

This patch implements an automatic fallback to internal pacing.

Pacing is requested either by BBR or use of SO_MAX_PACING_RATE option.

If sch_fq happens to be in the egress path, pacing is delegated to
the qdisc, otherwise pacing is done by TCP itself.

One advantage of pacing from TCP stack is to get more precise rtt
estimations, and less work done from TX completion, since TCP Small
queue limits are not generally hit. Setups with single TX queue but
many cpus might even benefit from this.

Note that unlike sch_fq, we do not take into account header sizes.
Taking care of these headers would add additional complexity for
no practical differences in behavior.

Some performance numbers using 800 TCP_STREAM flows rate limited to
~48 Mbit per second on 40Gbit NIC.

If MQ+pfifo_fast is used on the NIC :

$ sar -n DEV 1 5 | grep eth
14:48:44 eth0 725743.00 2932134.00 46776.76 4335184.68 0.00 0.00 1.00
14:48:45 eth0 725349.00 2932112.00 46751.86 4335158.90 0.00 0.00 0.00
14:48:46 eth0 725101.00 2931153.00 46735.07 4333748.63 0.00 0.00 0.00
14:48:47 eth0 725099.00 2931161.00 46735.11 4333760.44 0.00 0.00 1.00
14:48:48 eth0 725160.00 2931731.00 46738.88 4334606.07 0.00 0.00 0.00
Average: eth0 725290.40 2931658.20 46747.54 4334491.74 0.00 0.00 0.40
$ vmstat 1 5
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
r b swpd free buff cache si so bi bo in cs us sy id wa st
4 0 0 259825920 45644 2708324 0 0 21 2 247 98 0 0 100 0 0
4 0 0 259823744 45644 2708356 0 0 0 0 2400825 159843 0 19 81 0 0
0 0 0 259824208 45644 2708072 0 0 0 0 2407351 159929 0 19 81 0 0
1 0 0 259824592 45644 2708128 0 0 0 0 2405183 160386 0 19 80 0 0
1 0 0 259824272 45644 2707868 0 0 0 32 2396361 158037 0 19 81 0 0

Now use MQ+FQ :

lpaa23:~# echo fq >/proc/sys/net/core/default_qdisc
lpaa23:~# tc qdisc replace dev eth0 root mq

$ sar -n DEV 1 5 | grep eth
14:49:57 eth0 678614.00 2727930.00 43739.13 4033279.14 0.00 0.00 0.00
14:49:58 eth0 677620.00 2723971.00 43674.69 4027429.62 0.00 0.00 1.00
14:49:59 eth0 676396.00 2719050.00 43596.83 4020125.02 0.00 0.00 0.00
14:50:00 eth0 675197.00 2714173.00 43518.62 4012938.90 0.00 0.00 1.00
14:50:01 eth0 676388.00 2719063.00 43595.47 4020171.64 0.00 0.00 0.00
Average: eth0 676843.00 2720837.40 43624.95 4022788.86 0.00 0.00 0.40
$ vmstat 1 5
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
r b swpd free buff cache si so bi bo in cs us sy id wa st
2 0 0 259832240 46008 2710912 0 0 21 2 223 192 0 1 99 0 0
1 0 0 259832896 46008 2710744 0 0 0 0 1702206 198078 0 17 82 0 0
0 0 0 259830272 46008 2710596 0 0 0 0 1696340 197756 1 17 83 0 0
4 0 0 259829168 46024 2710584 0 0 16 0 1688472 197158 1 17 82 0 0
3 0 0 259830224 46024 2710408 0 0 0 0 1692450 197212 0 18 82 0 0

As expected, number of interrupts per second is very different.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Van Jacobson <vanj@google.com>
Cc: Jerry Chu <hkchu@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: use kvmalloc with __GFP_REPEAT rather than open coded variant

fq_alloc_node, alloc_netdev_mqs and netif_alloc* open code kmalloc with
vmalloc fallback. Use the kvmalloc variant instead. Keep the
__GFP_REPEAT flag based on explanation from Eric:

"At the time, tests on the hardware I had in my labs showed that
vmalloc() could deliver pages spread all over the memory and that was
a small penalty (once memory is fragmented enough, not at boot time)"

The way how the code is constructed means, however, that we prefer to go
and hit the OOM killer before we fall back to the vmalloc for requests
<=32kB (with 4kB pages) in the current code. This is rather disruptive
for something that can be achived with the fallback. On the other hand
__GFP_REPEAT doesn't have any useful semantic for these requests. So
the effect of this patch is that requests which fit into 32kB will fall
back to vmalloc easier now.

Link: http://lkml.kernel.org/r/20170306103327.2766-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Eric Dumazet <edumazet@google.com>
Cc: David Miller <davem@davemloft.net>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

netlink: pass extended ACK struct to parsing functions

Pass the new extended ACK reporting struct to all of the generic
netlink parsing functions. For now, pass NULL in almost all callers
(except for some in the core.)

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: use rb_entry()

To make the code clearer, use rb_entry() instead of container_of() to
deal with rbtree.

Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: use hash_ptr()

When I wrote sch_fq.c, hash_ptr() on 64bit arches was awful,
and I chose hash_32().

Linus Torvalds and George Spelvin fixed this issue, so we can
use hash_ptr() to get more entropy on 64bit arches with Terabytes
of memory, and avoid the cast games.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: account for schedule/timers drifts

It looks like the following patch can make FQ very precise, even in VM
or stressed hosts. It matters at high pacing rates.

We take into account the difference between the time that was programmed
when last packet was sent, and current time (a drift of tens of usecs is
often observed)

Add an EWMA of the unthrottle latency to help diagnostics.

This latency is the difference between current time and oldest packet in
delayed RB-tree. This accounts for the high resolution timer latency,
but can be different under stress, as fq_check_throttled() can be
opportunistically be called from a dequeue() called after an enqueue()
for a different flow.

Tested:
// Start a 10Gbit flow
$ netperf --google-pacing-rate 1250000000 -H lpaa24 -l 10000 -- -K bbr &

Before patch :
$ sar -n DEV 10 5 | grep eth0 | grep Average
Average: eth0 17106.04 756876.84 1102.75 1119049.02 0.00 0.00 0.52

After patch :
$ sar -n DEV 10 5 | grep eth0 | grep Average
Average: eth0 17867.00 800245.90 1151.77 1183172.12 0.00 0.00 0.52

A new iproute2 tc can output the 'unthrottle latency' :

$ tc -s qd sh dev eth0 | grep latency
0 gc, 0 highprio, 32490767 throttled, 2382 ns latency

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: add low_rate_threshold parameter

This commit adds to the fq module a low_rate_threshold parameter to
insert a delay after all packets if the socket requests a pacing rate
below the threshold.

This helps achieve more precise control of the sending rate with
low-rate paths, especially policers. The basic issue is that if a
congestion control module detects a policer at a certain rate, it may
want fq to be able to shape to that policed rate. That way the sender
can avoid policer drops by having the packets arrive at the policer at
or just under the policed rate.

The default threshold of 550Kbps was chosen analytically so that for
policers or links at 500Kbps or 512Kbps fq would very likely invoke
this mechanism, even if the pacing rate was briefly slightly above the
available bandwidth. This value was then empirically validated with
two years of production testing on YouTube video servers.

Signed-off-by: Van Jacobson <vanj@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Nandita Dukkipati <nanditad@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

pkt_sched: fq: use proper locking in fq_dump_stats()

When fq is used on 32bit kernels, we need to lock the qdisc before
copying 64bit fields.

Otherwise "tc -s qdisc ..." might report bogus values.

Fixes: afe4fd062416 ("pkt_sched: fq: Fair Queue packet scheduler")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: drop packets after root qdisc lock is released

Qdisc performance suffers when packets are dropped at enqueue()
time because drops (kfree_skb()) are done while qdisc lock is held,
delaying a dequeue() draining the queue.

Nominal throughput can be reduced by 50 % when this happens,
at a time we would like the dequeue() to proceed as fast as possible.

Even FQ is vulnerable to this problem, while one of FQ goals was
to provide some flow isolation.

This patch adds a 'struct sk_buff **to_free' parameter to all
qdisc->enqueue(), and in qdisc_drop() helper.

I measured a performance increase of up to 12 %, but this patch
is a prereq so that future batches in enqueue() can fly.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: sch_fq: defer skb freeing

Both fq_change() and fq_reset() can use rtnl_kfree_skbs()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: remove generic throttled management

__QDISC_STATE_THROTTLED bit manipulation is rather expensive
for HTB and few others.

I already removed it for sch_fq in commit f2600cf02b5b
("net: sched: avoid costly atomic operation in fq_dequeue()")
and so far nobody complained.

When one ore more packets are stuck in one or more throttled
HTB class, a htb dequeue() performs two atomic operations
to clear/set __QDISC_STATE_THROTTLED bit, while root qdisc
lock is held.

Removing this pair of atomic operations bring me a 8 % performance
increase on 200 TCP_RR tests, in presence of throttled classes.

This patch has no side effect, since nothing actually uses
disc_is_throttled() anymore.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: update hierarchical backlog too

When the bottom qdisc decides to, for example, drop some packet,
it calls qdisc_tree_decrease_qlen() to update the queue length
for all its ancestors, we need to update the backlog too to
keep the stats on root qdisc accurate.

Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: synack packets can be attached to request sockets

selinux needs few changes to accommodate fact that SYNACK messages
can be attached to a request socket, lacking sk_security pointer

(Only syncookies are still attached to a TCP_LISTEN socket)

Adds a new sk_listener() helper, and use it in selinux and sch_fq

Fixes: ca6fb0651883 ("tcp: attach SYNACK messages to request sockets instead of listener")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported by: kernel test robot <ying.huang@linux.intel.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Eric Paris <eparis@parisplace.org>
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: attach SYNACK messages to request sockets instead of listener

If a listen backlog is very big (to avoid syncookies), then
the listener sk->sk_wmem_alloc is the main source of false
sharing, as we need to touch it twice per SYNACK re-transmit
and TX completion.

(One SYN packet takes listener lock once, but up to 6 SYNACK
are generated)

By attaching the skb to the request socket, we remove this
source of contention.

Tested:

listen(fd, 10485760); // single listener (no SO_REUSEPORT)
16 RX/TX queue NIC
Sustain a SYNFLOOD attack of ~320,000 SYN per second,
Sending ~1,400,000 SYNACK per second.
Perf profiles now show listener spinlock being next bottleneck.

20.29% [kernel] [k] queued_spin_lock_slowpath
10.06% [kernel] [k] __inet_lookup_established
5.12% [kernel] [k] reqsk_timer_handler
3.22% [kernel] [k] get_next_timer_interrupt
3.00% [kernel] [k] tcp_make_synack
2.77% [kernel] [k] ipt_do_table
2.70% [kernel] [k] run_timer_softirq
2.50% [kernel] [k] ip_finish_output
2.04% [kernel] [k] cascade

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

pkt_sched: fq: correct spelling of locally

Correct spelling of locally.

Also remove extra space before tab character in struct fq_flow.

Signed-off-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

pkt_sched: fq: better control of DDOS traffic

FQ has a fast path for skb attached to a socket, as it does not
have to compute a flow hash. But for other packets, FQ being non
stochastic means that hosts exposed to random Internet traffic
can allocate million of flows structure (104 bytes each) pretty
easily. Not only host can OOM, but lookup in RB trees can take
too much cpu and memory resources.

This patch adds a new attribute, orphan_mask, that is adding
possibility of having a stochastic hash for orphaned skb.

Its default value is 1024 slots, to mimic SFQ behavior.

Note: This does not apply to locally generated TCP traffic,
and no locally generated traffic will share a flow structure
with another perfect or stochastic flow.

This patch also handles the specific case of SYNACK messages:

They are attached to the listener socket, and therefore all map
to a single hash bucket. If listener have set SO_MAX_PACING_RATE,
hoping to have new accepted socket inherit this rate, SYNACK
might be paced and even dropped.

This is very similar to an internal patch Google have used more
than one year.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tcp: do not pace pure ack packets

When we added pacing to TCP, we decided to let sch_fq take care
of actual pacing.

All TCP had to do was to compute sk->pacing_rate using simple formula:

sk->pacing_rate = 2 * cwnd * mss / rtt

It works well for senders (bulk flows), but not very well for receivers
or even RPC :

cwnd on the receiver can be less than 10, rtt can be around 100ms, so we
can end up pacing ACK packets, slowing down the sender.

Really, only the sender should pace, according to its own logic.

Instead of adding a new bit in skb, or call yet another flow
dissection, we tweak skb->truesize to a small value (2), and
we instruct sch_fq to use new helper and not pace pure ack.

Note this also helps TCP small queue, as ack packets present
in qdisc/NIC do not prevent sending a data packet (RPC workload)

This helps to reduce tx completion overhead, ack packets can use regular
sock_wfree() instead of tcp_wfree() which is a bit more expensive.

This has no impact in the case packets are sent to loopback interface,
as we do not coalesce ack packets (were we would detect skb->truesize
lie)

In case netem (with a delay) is used, skb_orphan_partial() also sets
skb->truesize to 1.

This patch is a combination of two patches we used for about one year at
Google.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

pkt_sched: fq: avoid hang when quantum 0

Configuring fq with quantum 0 hangs the system, presumably because of a
non-interruptible infinite loop. Either way quantum 0 does not make sense.

Reproduce with:
sudo tc qdisc add dev lo root fq quantum 0 initial_quantum 0
ping 127.0.0.1

Signed-off-by: Kenneth Klette Jonassen <kennetkl@ifi.uio.no>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

pkt_sched: fq: remove useless TIME_WAIT check

TIME_WAIT sockets are not owning any skb.

ip_send_unicast_reply() and tcp_v6_send_response() both use
regular sockets.

We can safely remove a test in sch_fq and save one cache line miss,
as sk_state is far away from sk_pacing_rate.

Tested at Google for about one year.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

pkt_sched: fq: increase max delay from 125 ms to one second

FQ/pacing has a clamp of delay of 125 ms, to avoid some possible harm.

It turns out this delay is too small to allow pacing low rates :
Some ISP setup very aggressive policers as low as 16kbit.

Now TCP stack has spurious rtx prevention, it seems safe to increase
this fixed parameter, without adding a qdisc attribute.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: sched: avoid costly atomic operation in fq_dequeue()

Standard qdisc API to setup a timer implies an atomic operation on every
packet dequeue : qdisc_unthrottled()

It turns out this is not really needed for FQ, as FQ has no concept of
global qdisc throttling, being a qdisc handling many different flows,
some of them can be throttled, while others are not.

Fix is straightforward : add a 'bool throttle' to
qdisc_watchdog_schedule_ns(), and remove calls to qdisc_unthrottled()
in sch_fq.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: sched: implement qstat helper routines

This adds helpers to manipulate qstats logic and replaces locations
that touch the counters directly. This simplifies future patches
to push qstats onto per cpu counters.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: use ktime_get_ns() and ktime_get_real_ns() helpers

ktime_get_ns() replaces ktime_to_ns(ktime_get())

ktime_get_real_ns() replaces ktime_to_ns(ktime_get_real())

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: use the new API kvfree()

It is available since v3.15-rc5.

Cc: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net_sched: return nla_nest_end() instead of skb->len

nla_nest_end() already has return skb->len, so replace
return skb->len with return nla_nest_end instead().

Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

pkt_sched: fq: do not hold qdisc lock while allocating memory

Resizing fq hash table allocates memory while holding qdisc spinlock,
with BH disabled.

This is definitely not good, as allocation might sleep.

We can drop the lock and get it when needed, we hold RTNL so no other
changes can happen at the same time.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: afe4fd062416 ("pkt_sched: fq: Fair Queue packet scheduler")
Signed-off-by: David S. Miller <davem@davemloft.net>

pkt_sched: fq: do not hold qdisc lock while allocating memory

Resizing fq hash table allocates memory while holding qdisc spinlock,
with BH disabled.

This is definitely not good, as allocation might sleep.

We can drop the lock and get it when needed, we hold RTNL so no other
changes can happen at the same time.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: afe4fd062416 ("pkt_sched: fq: Fair Queue packet scheduler")
Signed-off-by: David S. Miller <davem@davemloft.net>

net: Change skb_get_rxhash to skb_get_hash

Changing name of function as part of making the hash in skbuff to be
generic property, not just for receive path.

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

pkt_sched: fq: more robust memory allocation

This patch brings NUMA support and automatic fallback to vmalloc()
in case kmalloc() failed to allocate FQ hash table.

NUMA support depends on XPS being setup for the device before
qdisc allocation. After a XPS change, it might be worth creating
qdisc hierarchy again.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

pkt_sched: fq: fix pacing for small frames

For performance reasons, sch_fq tried hard to not setup timers for every
sent packet, using a quantum based heuristic : A delay is setup only if
the flow exhausted its credit.

Problem is that application limited flows can refill their credit
for every queued packet, and they can evade pacing.

This problem can also be triggered when TCP flows use small MSS values,
as TSO auto sizing builds packets that are smaller than the default fq
quantum (3028 bytes)

This patch adds a 40 ms delay to guard flow credit refill.

Fixes: afe4fd062416 ("pkt_sched: fq: Fair Queue packet scheduler")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Maciej Żenczykowski <maze@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

pkt_sched: fq: warn users using defrate

Commit 7eec4174ff29 ("pkt_sched: fq: fix non TCP flows pacing")
obsoleted TCA_FQ_FLOW_DEFAULT_RATE without notice for the users.

Suggested by David Miller

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

pkt_sched: fq: change classification of control packets

Initial sch_fq implementation copied code from pfifo_fast to classify
a packet as a high prio packet.

This clashes with setups using PRIO with say 7 bands, as one of the
band could be incorrectly (mis)classified by FQ.

Packets would be queued in the 'internal' queue, and no pacing ever
happen for this special queue.

Fixes: afe4fd062416 ("pkt_sched: fq: Fair Queue packet scheduler")
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Stephen Hemminger <stephen@networkplumber.org>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

pkt_sched: fq: clear time_next_packet for reused flows

When a socket is freed/reallocated, we need to clear time_next_packet
or else we can inherit a prior value and delay first packets of the
new flow.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

pkt_sched: fq: fix non TCP flows pacing

Steinar reported FQ pacing was not working for UDP flows.

It looks like the initial sk->sk_pacing_rate value of 0 was
a wrong choice. We should init it to ~0U (unlimited)

Then, TCA_FQ_FLOW_DEFAULT_RATE should be removed because it makes
no real sense. The default rate is really unlimited, and we
need to avoid a zero divide.

Reported-by: Steinar H. Gunderson <sesse@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

pkt_sched: fq: fix typo for initial_quantum

TCA_FQ_INITIAL_QUANTUM should set q->initial_quantum

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

pkt_sched: fq: rate limiting improvements

FQ rate limiting suffers from two problems, reported
by Steinar :

1) FQ enforces a delay when flow quantum is exhausted in order
to reduce cpu overhead. But if packets are small, current
delay computation is slightly wrong, and observed rates can
be too high.

Steinar had this problem because he disabled TSO and GSO,
and default FQ quantum is 2*1514.

(Of course, I wish recent TSO auto sizing changes will help
to not having to disable TSO in the first place)

2) maxrate was not used for forwarded flows (skbs not attached
to a socket)

Tested:

tc qdisc add dev eth0 root est 1sec 4sec fq maxrate 8Mbit
netperf -H lpq84 -l 1000 &
sleep 10 ; tc -s qdisc show dev eth0
qdisc fq 8003: root refcnt 32 limit 10000p flow_limit 100p buckets 1024
quantum 3028 initial_quantum 15140 maxrate 8000Kbit
Sent 16819357 bytes 11258 pkt (dropped 0, overlimits 0 requeues 0)
rate 7831Kbit 653pps backlog 7570b 5p requeues 0
44 flows (43 inactive, 1 throttled), next packet delay 2977352 ns
0 gc, 0 highprio, 5545 throttled

lpq83:~# tcpdump -p -i eth0 host lpq84 -c 12
09:02:52.079484 IP lpq83 > lpq84: . 1389536928:1389538376(1448) ack 3808678021 win 457 <nop,nop,timestamp 961812 572609068>
09:02:52.079499 IP lpq83 > lpq84: . 1448:2896(1448) ack 1 win 457 <nop,nop,timestamp 961812 572609068>
09:02:52.079906 IP lpq84 > lpq83: . ack 2896 win 16384 <nop,nop,timestamp 572609080 961812>
09:02:52.082568 IP lpq83 > lpq84: . 2896:4344(1448) ack 1 win 457 <nop,nop,timestamp 961815 572609071>
09:02:52.082581 IP lpq83 > lpq84: . 4344:5792(1448) ack 1 win 457 <nop,nop,timestamp 961815 572609071>
09:02:52.083017 IP lpq84 > lpq83: . ack 5792 win 16384 <nop,nop,timestamp 572609083 961815>
09:02:52.085678 IP lpq83 > lpq84: . 5792:7240(1448) ack 1 win 457 <nop,nop,timestamp 961818 572609074>
09:02:52.085693 IP lpq83 > lpq84: . 7240:8688(1448) ack 1 win 457 <nop,nop,timestamp 961818 572609074>
09:02:52.086117 IP lpq84 > lpq83: . ack 8688 win 16384 <nop,nop,timestamp 572609086 961818>
09:02:52.088792 IP lpq83 > lpq84: . 8688:10136(1448) ack 1 win 457 <nop,nop,timestamp 961821 572609077>
09:02:52.088806 IP lpq83 > lpq84: . 10136:11584(1448) ack 1 win 457 <nop,nop,timestamp 961821 572609077>
09:02:52.089217 IP lpq84 > lpq83: . ack 11584 win 16384 <nop,nop,timestamp 572609090 961821>

Reported-by: Steinar H. Gunderson <sesse@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

pkt_sched: fq: qdisc dismantle fixes

fq_reset() should drops all packets in queue, including
throttled flows.

This patch moves code from fq_destroy() to fq_reset()
to do the cleaning.

fq_change() must stop calling fq_dequeue() if all remaining
packets are from throttled flows.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

pkt_sched: fq: prefetch() fix

kbuild bot reported following m68k build error :

net/sched/sch_fq.c: In function 'fq_dequeue':
>> net/sched/sch_fq.c:491:2: error: implicit declaration of function
'prefetch' [-Werror=implicit-function-declaration]
cc1: some warnings being treated as errors

While we are fixing this, move this prefetch() call a bit earlier.

Reported-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

pkt_sched: fq: Fair Queue packet scheduler

- Uses perfect flow match (not stochastic hash like SFQ/FQ_codel)
- Uses the new_flow/old_flow separation from FQ_codel
- New flows get an initial credit allowing IW10 without added delay.
- Special FIFO queue for high prio packets (no need for PRIO + FQ)
- Uses a hash table of RB trees to locate the flows at enqueue() time
- Smart on demand gc (at enqueue() time, RB tree lookup evicts old
unused flows)
- Dynamic memory allocations.
- Designed to allow millions of concurrent flows per Qdisc.
- Small memory footprint : ~8K per Qdisc, and 104 bytes per flow.
- Single high resolution timer for throttled flows (if any).
- One RB tree to link throttled flows.
- Ability to have a max rate per flow. We might add a socket option
to add per socket limitation.

Attempts have been made to add TCP pacing in TCP stack, but this
seems to add complex code to an already complex stack.

TCP pacing is welcomed for flows having idle times, as the cwnd
permits TCP stack to queue a possibly large number of packets.

This removes the 'slow start after idle' choice, hitting badly
large BDP flows, and applications delivering chunks of data
as video streams.

Nicely spaced packets :
Here interface is 10Gbit, but flow bottleneck is ~20Mbit

cwin is big, yet FQ avoids the typical bursts generated by TCP
(as in netperf TCP_RR -- -r 100000,100000)

15:01:23.545279 IP A > B: . 78193:81089(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805>
15:01:23.545394 IP B > A: . ack 81089 win 3668 <nop,nop,timestamp 11597985 1115>
15:01:23.546488 IP A > B: . 81089:83985(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805>
15:01:23.546565 IP B > A: . ack 83985 win 3668 <nop,nop,timestamp 11597986 1115>
15:01:23.547713 IP A > B: . 83985:86881(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805>
15:01:23.547778 IP B > A: . ack 86881 win 3668 <nop,nop,timestamp 11597987 1115>
15:01:23.548911 IP A > B: . 86881:89777(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805>
15:01:23.548949 IP B > A: . ack 89777 win 3668 <nop,nop,timestamp 11597988 1115>
15:01:23.550116 IP A > B: . 89777:92673(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805>
15:01:23.550182 IP B > A: . ack 92673 win 3668 <nop,nop,timestamp 11597989 1115>
15:01:23.551333 IP A > B: . 92673:95569(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805>
15:01:23.551406 IP B > A: . ack 95569 win 3668 <nop,nop,timestamp 11597991 1115>
15:01:23.552539 IP A > B: . 95569:98465(2896) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805>
15:01:23.552576 IP B > A: . ack 98465 win 3668 <nop,nop,timestamp 11597992 1115>
15:01:23.553756 IP A > B: . 98465:99913(1448) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805>
15:01:23.554138 IP A > B: P 99913:100001(88) ack 65248 win 3125 <nop,nop,timestamp 1115 11597805>
15:01:23.554204 IP B > A: . ack 100001 win 3668 <nop,nop,timestamp 11597993 1115>
15:01:23.554234 IP B > A: . 65248:68144(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115>
15:01:23.555620 IP B > A: . 68144:71040(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115>
15:01:23.557005 IP B > A: . 71040:73936(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115>
15:01:23.558390 IP B > A: . 73936:76832(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115>
15:01:23.559773 IP B > A: . 76832:79728(2896) ack 100001 win 3668 <nop,nop,timestamp 11597993 1115>
15:01:23.561158 IP B > A: . 79728:82624(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115>
15:01:23.562543 IP B > A: . 82624:85520(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115>
15:01:23.563928 IP B > A: . 85520:88416(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115>
15:01:23.565313 IP B > A: . 88416:91312(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115>
15:01:23.566698 IP B > A: . 91312:94208(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115>
15:01:23.568083 IP B > A: . 94208:97104(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115>
15:01:23.569467 IP B > A: . 97104:100000(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115>
15:01:23.570852 IP B > A: . 100000:102896(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115>
15:01:23.572237 IP B > A: . 102896:105792(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115>
15:01:23.573639 IP B > A: . 105792:108688(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115>
15:01:23.575024 IP B > A: . 108688:111584(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115>
15:01:23.576408 IP B > A: . 111584:114480(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115>
15:01:23.577793 IP B > A: . 114480:117376(2896) ack 100001 win 3668 <nop,nop,timestamp 11597994 1115>

TCP timestamps show that most packets from B were queued in the same ms
timeframe (TSval 1159799{3,4}), but FQ managed to send them right
in time to avoid a big burst.

In slow start or steady state, very few packets are throttled [1]

FQ gets a bunch of tunables as :

limit : max number of packets on whole Qdisc (default 10000)

flow_limit : max number of packets per flow (default 100)

quantum : the credit per RR round (default is 2 MTU)

initial_quantum : initial credit for new flows (default is 10 MTU)

maxrate : max per flow rate (default : unlimited)

buckets : number of RB trees (default : 1024) in hash table.
(consumes 8 bytes per bucket)

[no]pacing : disable/enable pacing (default is enable)

All of them can be changed on a live qdisc.

$ tc qd add dev eth0 root fq help
Usage: ... fq [ limit PACKETS ] [ flow_limit PACKETS ]
[ quantum BYTES ] [ initial_quantum BYTES ]
[ maxrate RATE ] [ buckets NUMBER ]
[ [no]pacing ]

$ tc -s -d qd
qdisc fq 8002: dev eth0 root refcnt 32 limit 10000p flow_limit 100p buckets 256 quantum 3028 initial_quantum 15140
Sent 216532416 bytes 148395 pkt (dropped 0, overlimits 0 requeues 14)
backlog 0b 0p requeues 14
511 flows, 511 inactive, 0 throttled
110 gc, 0 highprio, 0 retrans, 1143 throttled, 0 flows_plimit

[1] Except if initial srtt is overestimated, as if using
cached srtt in tcp metrics. We'll provide a fix for this issue.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>