ipvs: don't ignore errors in case refcounting ip_vs module fails

if the IPVS module is removed while the sync daemon is starting, there is
a small gap where try_module_get() might fail getting the refcount inside
ip_vs_use_count_inc(). Then, the refcounts of IPVS module are unbalanced,
and the subsequent call to stop_sync_thread() causes the following splat:

WARNING: CPU: 0 PID: 4013 at kernel/module.c:1146 module_put.part.44+0x15b/0x290
Modules linked in: ip_vs(-) nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 veth ip6table_filter ip6_tables iptable_filter binfmt_misc intel_rapl_msr intel_rapl_common crct10dif_pclmul crc32_pclmul ext4 mbcache jbd2 ghash_clmulni_intel snd_hda_codec_generic ledtrig_audio snd_hda_intel snd_intel_nhlt snd_hda_codec snd_hda_core snd_hwdep snd_seq snd_seq_device snd_pcm aesni_intel crypto_simd cryptd glue_helper joydev pcspkr snd_timer virtio_balloon snd soundcore i2c_piix4 nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs libcrc32c ata_generic pata_acpi virtio_net net_failover virtio_blk failover virtio_console qxl drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ata_piix ttm crc32c_intel serio_raw drm virtio_pci libata virtio_ring virtio floppy dm_mirror dm_region_hash dm_log dm_mod [last unloaded: nf_defrag_ipv6]
CPU: 0 PID: 4013 Comm: modprobe Tainted: G W 5.4.0-rc1.upstream+ #741
Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
RIP: 0010:module_put.part.44+0x15b/0x290
Code: 04 25 28 00 00 00 0f 85 18 01 00 00 48 83 c4 68 5b 5d 41 5c 41 5d 41 5e 41 5f c3 89 44 24 28 83 e8 01 89 c5 0f 89 57 ff ff ff <0f> 0b e9 78 ff ff ff 65 8b 1d 67 83 26 4a 89 db be 08 00 00 00 48
RSP: 0018:ffff888050607c78 EFLAGS: 00010297
RAX: 0000000000000003 RBX: ffffffffc1420590 RCX: ffffffffb5db0ef9
RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffffffc1420590
RBP: 00000000ffffffff R08: fffffbfff82840b3 R09: fffffbfff82840b3
R10: 0000000000000001 R11: fffffbfff82840b2 R12: 1ffff1100a0c0f90
R13: ffffffffc1420200 R14: ffff88804f533300 R15: ffff88804f533ca0
FS: 00007f8ea9720740(0000) GS:ffff888053800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3245abe000 CR3: 000000004c28a006 CR4: 00000000001606f0
Call Trace:
stop_sync_thread+0x3a3/0x7c0 [ip_vs]
ip_vs_sync_net_cleanup+0x13/0x50 [ip_vs]
ops_exit_list.isra.5+0x94/0x140
unregister_pernet_operations+0x29d/0x460
unregister_pernet_device+0x26/0x60
ip_vs_cleanup+0x11/0x38 [ip_vs]
__x64_sys_delete_module+0x2d5/0x400
do_syscall_64+0xa5/0x4e0
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f8ea8bf0db7
Code: 73 01 c3 48 8b 0d b9 80 2c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 b0 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 89 80 2c 00 f7 d8 64 89 01 48
RSP: 002b:00007ffcd38d2fe8 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
RAX: ffffffffffffffda RBX: 0000000002436240 RCX: 00007f8ea8bf0db7
RDX: 0000000000000000 RSI: 0000000000000800 RDI: 00000000024362a8
RBP: 0000000000000000 R08: 00007f8ea8eba060 R09: 00007f8ea8c658a0
R10: 00007ffcd38d2a60 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000001 R14: 00000000024362a8 R15: 0000000000000000
irq event stamp: 4538
hardirqs last enabled at (4537): [<ffffffffb6193dde>] quarantine_put+0x9e/0x170
hardirqs last disabled at (4538): [<ffffffffb5a0556a>] trace_hardirqs_off_thunk+0x1a/0x20
softirqs last enabled at (4522): [<ffffffffb6f8ebe9>] sk_common_release+0x169/0x2d0
softirqs last disabled at (4520): [<ffffffffb6f8eb3e>] sk_common_release+0xbe/0x2d0

Check the return value of ip_vs_use_count_inc() and let its caller return
proper error. Inside do_ip_vs_set_ctl() the module is already refcounted,
we don't need refcount/derefcount there. Finally, in register_ip_vs_app()
and start_sync_thread(), take the module refcount earlier and ensure it's
released in the error path.

Change since v1:
- better return values in case of failure of ip_vs_use_count_inc(),
thanks to Julian Anastasov
- no need to increase/decrease the module refcount in ip_vs_set_ctl(),
thanks to Julian Anastasov

Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>

treewide: Add SPDX license identifier for missed files

Add SPDX license identifiers to all files which:

- Have no license information of any form

- Have EXPORT_.*_SYMBOL_GPL inside which was used in the
initial scan/conversion to ignore the file

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

netfilter: Deletion of unnecessary checks before two function calls

The functions free_percpu() and module_put() test whether their argument
is NULL and then return immediately. Thus the test around the call is
not needed.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Acked-by: Julian Anastasov <ja@ssi.bg>
Acked-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

ipvs: convert services to rcu

This is the final step in RCU conversion.

Things that are removed:

- svc->usecnt: now svc is accessed under RCU read lock
- svc->inc: and some unused code
- ip_vs_bind_pe and ip_vs_unbind_pe: no ability to replace PE
- __ip_vs_svc_lock: replaced with RCU
- IP_VS_WAIT_WHILE: now readers lookup svcs and dests under
RCU and work in parallel with configuration

Other changes:

- before now, a RCU read-side critical section included the
calling of the schedule method, now it is extended to include
service lookup
- ip_vs_svc_table and ip_vs_svc_fwm_table are now using hlist
- svc->pe and svc->scheduler remain to the end (of grace period),
the schedulers are prepared for such RCU readers
even after done_service is called but they need
to use synchronize_rcu because last ip_vs_scheduler_put
can happen while RCU read-side critical sections
use an outdated svc->scheduler pointer
- as planned, update_service is removed
- empty services can be freed immediately after grace period.
If dests were present, the services are freed from
the dest trash code

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>

ipvs: convert locks used in persistence engines

Allow the readers to use RCU lock and for
PE module registrations use global mutex instead of
spinlock. All PE modules need to use synchronize_rcu
in their module exit handler.

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off by: Hans Schillstrom <hans@schillstrom.com>
Signed-off-by: Simon Horman <horms@verge.net.au>

IPVS: Backup, Adding Version 1 receive capability

Functionality improvements
* flags changed from 16 to 32 bits
* fwmark added (32 bits)
* timeout in sec. added (32 bits)
* pe data added (Variable length)
* IPv6 capabilities (3x16 bytes for addr.)
* Version and type in every conn msg.

ip_vs_process_message() now handles Version 1 messages
and will call ip_vs_process_message_v0() for version 0 messages.

ip_vs_proc_conn() is common for both version, and handles the update of
connection hash.

ip_vs_conn_fill_param_sync() - Version 1 messages only
ip_vs_conn_fill_param_sync_v0() - Version 0 messages only

Signed-off-by: Hans Schillstrom <hans.schillstrom@ericsson.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>

IPVS: Add persistence engine to connection entry

The dest of a connection may not exist if it has been created as the result
of connection synchronisation. But in order for connection entries for
templates with persistence engine data created through connection
synchronisation to be valid access to the persistence engine pointer is
required. So add the persistence engine to the connection itself.

Signed-off-by: Simon Horman <horms@verge.net.au>

IPVS: management of persistence engine modules

This is based heavily on the scheduler management code

Signed-off-by: Simon Horman <horms@verge.net.au>
Acked-by: Julian Anastasov <ja@ssi.bg>