net: ks8851: Handle softirqs at the end of IRQ thread to fix hang

The ks8851_irq() thread may call ks8851_rx_pkts() in case there are
any packets in the MAC FIFO, which calls netif_rx(). This netif_rx()
implementation is guarded by local_bh_disable() and local_bh_enable().
The local_bh_enable() may call do_softirq() to run softirqs in case
any are pending. One of the softirqs is net_rx_action, which ultimately
reaches the driver .start_xmit callback. If that happens, the system
hangs. The entire call chain is below:

ks8851_start_xmit_par from netdev_start_xmit
netdev_start_xmit from dev_hard_start_xmit
dev_hard_start_xmit from sch_direct_xmit
sch_direct_xmit from __dev_queue_xmit
__dev_queue_xmit from __neigh_update
__neigh_update from neigh_update
neigh_update from arp_process.constprop.0
arp_process.constprop.0 from __netif_receive_skb_one_core
__netif_receive_skb_one_core from process_backlog
process_backlog from __napi_poll.constprop.0
__napi_poll.constprop.0 from net_rx_action
net_rx_action from __do_softirq
__do_softirq from call_with_stack
call_with_stack from do_softirq
do_softirq from __local_bh_enable_ip
__local_bh_enable_ip from netif_rx
netif_rx from ks8851_irq
ks8851_irq from irq_thread_fn
irq_thread_fn from irq_thread
irq_thread from kthread
kthread from ret_from_fork

The hang happens because ks8851_irq() first locks a spinlock in
ks8851_par.c ks8851_lock_par() spin_lock_irqsave(&ksp->lock, ...)
and with that spinlock locked, calls netif_rx(). Once the execution
reaches ks8851_start_xmit_par(), it calls ks8851_lock_par() again
which attempts to claim the already locked spinlock again, and the
hang happens.

Move the do_softirq() call outside of the spinlock protected section
of ks8851_irq() by disabling BHs around the entire spinlock protected
section of ks8851_irq() handler. Place local_bh_enable() outside of
the spinlock protected section, so that it can trigger do_softirq()
without the ks8851_par.c ks8851_lock_par() spinlock being held, and
safely call ks8851_start_xmit_par() without attempting to lock the
already locked spinlock.

Since ks8851_irq() is protected by local_bh_disable()/local_bh_enable()
now, replace netif_rx() with __netif_rx() which is not duplicating the
local_bh_disable()/local_bh_enable() calls.

Fixes: 797047f875b5 ("net: ks8851: Implement Parallel bus operations")
Signed-off-by: Marek Vasut <marex@denx.de>
Link: https://lore.kernel.org/r/20240405203204.82062-2-marex@denx.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: ks8851: Inline ks8851_rx_skb()

Both ks8851_rx_skb_par() and ks8851_rx_skb_spi() call netif_rx(skb),
inline the netif_rx(skb) call directly into ks8851_common.c and drop
the .rx_skb callback and ks8851_rx_skb() wrapper. This removes one
indirect call from the driver, no functional change otherwise.

Signed-off-by: Marek Vasut <marex@denx.de>
Link: https://lore.kernel.org/r/20240405203204.82062-1-marex@denx.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: ks8851: Fix TX stall caused by TX buffer overrun

There is a bug in the ks8851 Ethernet driver that more data is written
to the hardware TX buffer than actually available. This is caused by
wrong accounting of the free TX buffer space.

The driver maintains a tx_space variable that represents the TX buffer
space that is deemed to be free. The ks8851_start_xmit_spi() function
adds an SKB to a queue if tx_space is large enough and reduces tx_space
by the amount of buffer space it will later need in the TX buffer and
then schedules a work item. If there is not enough space then the TX
queue is stopped.

The worker function ks8851_tx_work() dequeues all the SKBs and writes
the data into the hardware TX buffer. The last packet will trigger an
interrupt after it was send. Here it is assumed that all data fits into
the TX buffer.

In the interrupt routine (which runs asynchronously because it is a
threaded interrupt) tx_space is updated with the current value from the
hardware. Also the TX queue is woken up again.

Now it could happen that after data was sent to the hardware and before
handling the TX interrupt new data is queued in ks8851_start_xmit_spi()
when the TX buffer space had still some space left. When the interrupt
is actually handled tx_space is updated from the hardware but now we
already have new SKBs queued that have not been written to the hardware
TX buffer yet. Since tx_space has been overwritten by the value from the
hardware the space is not accounted for.

Now we have more data queued then buffer space available in the hardware
and ks8851_tx_work() will potentially overrun the hardware TX buffer. In
many cases it will still work because often the buffer is written out
fast enough so that no overrun occurs but for example if the peer
throttles us via flow control then an overrun may happen.

This can be fixed in different ways. The most simple way would be to set
tx_space to 0 before writing data to the hardware TX buffer preventing
the queuing of more SKBs until the TX interrupt has been handled. I have
chosen a slightly more efficient (and still rather simple) way and
track the amount of data that is already queued and not yet written to
the hardware. When new SKBs are to be queued the already queued amount
of data is honoured when checking free TX buffer space.

I tested this with a setup of two linked KS8851 running iperf3 between
the two in bidirectional mode. Before the fix I got a stall after some
minutes. With the fix I saw now issues anymore after hours.

Fixes: 3ba81f3ece3c ("net: Micrel KS8851 SPI network driver")
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Ben Dooks <ben.dooks@codethink.co.uk>
Cc: Tristram Ha <Tristram.Ha@microchip.com>
Cc: netdev@vger.kernel.org
Cc: stable@vger.kernel.org # 5.10+
Signed-off-by: Ronald Wahl <ronald.wahl@raritan.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20231214181112.76052-1-rwahl@gmx.de
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net: ks8851: switch to using gpiod API

This patch switches the driver away from legacy gpio/of_gpio API to
gpiod API, and removes use of of_get_named_gpio_flags() which I want to
make private to gpiolib.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20220906204922.3789922-2-dmitry.torokhov@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net: ethernet: move from strlcpy with unused retval to strscpy

Follow the advice of the below link and prefer 'strscpy' in this
subsystem. Conversion is 1:1 because the return value is not used.
Generated by a coccinelle script.

Link: https://lore.kernel.org/r/CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw@mail.gmail.com/
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Petr Machata <petrm@nvidia.com> # For drivers/net/ethernet/mellanox/mlxsw
Acked-by: Geoff Levand <geoff@infradead.org> # For ps3_gelic_net and spider_net_ethtool
Acked-by: Tom Lendacky <thomas.lendacky@amd.com> # For drivers/net/ethernet/amd/xgbe/xgbe-ethtool.c
Acked-by: Marcin Wojtas <mw@semihalf.com> # For drivers/net/ethernet/marvell/mvpp2
Reviewed-by: Leon Romanovsky <leonro@nvidia.com> # For drivers/net/ethernet/mellanox/mlx{4|5}
Reviewed-by: Shay Agroskin <shayagr@amazon.com> # For drivers/net/ethernet/amazon/ena
Acked-by: Krzysztof Hałasa <khalasa@piap.pl> # For IXP4xx Ethernet
Link: https://lore.kernel.org/r/20220830201457.7984-3-wsa+renesas@sang-engineering.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

ethernet: use eth_hw_addr_set() in unmaintained drivers

Commit 406f42fa0d3c ("net-next: When a bond have a massive amount
of VLANs...") introduced a rbtree for faster Ethernet address look
up. To maintain netdev->dev_addr in this tree we need to make all
the writes to it got through appropriate helpers.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: ks8851: Make ks8851_remove_common() return void

Up to now ks8851_remove_common() returns zero unconditionally. Make it
return void instead which makes it easier to see in the callers that
there is no error to handle.

Also the return value of platform and spi remove callbacks is ignored
anyway.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

ethernet: use of_get_ethdev_address()

Use the new of_get_ethdev_address() helper for the cases
where dev->dev_addr is passed in directly as the destination.

@@
expression dev, np;
@@
- of_get_mac_address(np, dev->dev_addr)
+ of_get_ethdev_address(np, dev)

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

ethernet: use eth_hw_addr_set()

Convert all Ethernet drivers from memcpy(... ETH_ADDR)
to eth_hw_addr_set():

@@
expression dev, np;
@@
- memcpy(dev->dev_addr, np, ETH_ALEN)
+ eth_hw_addr_set(dev, np)

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: ks8851: fix link error

An object file cannot be built for both loadable module and built-in
use at the same time:

arm-linux-gnueabi-ld: drivers/net/ethernet/micrel/ks8851_common.o: in function `ks8851_probe_common':
ks8851_common.c:(.text+0xf80): undefined reference to `__this_module'

Change the ks8851_common code to be a standalone module instead,
and use Makefile logic to ensure this is built-in if at least one
of its two users is.

Fixes: 797047f875b5 ("net: ks8851: Implement Parallel bus operations")
Link: https://lore.kernel.org/netdev/20210125121937.3900988-1-arnd@kernel.org/
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Marek Vasut <marex@denx.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

dev_ioctl: split out ndo_eth_ioctl

Most users of ndo_do_ioctl are ethernet drivers that implement
the MII commands SIOCGMIIPHY/SIOCGMIIREG/SIOCSMIIREG, or hardware
timestamping with SIOCSHWTSTAMP/SIOCGHWTSTAMP.

Separate these from the few drivers that use ndo_do_ioctl to
implement SIOCBOND, SIOCBR and SIOCWANDEV commands.

This is a purely cosmetic change intended to help readers find
their way through the implementation.

Cc: Doug Ledford <dledford@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jay Vosburgh <j.vosburgh@gmail.com>
Cc: Veaceslav Falico <vfalico@gmail.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Vivien Didelot <vivien.didelot@gmail.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Vladimir Oltean <olteanv@gmail.com>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: linux-rdma@vger.kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: ks8851: Make ks8851_read_selftest() return void

clang points out that ret in ks8851_read_selftest() is set but unused:

drivers/net/ethernet/micrel/ks8851_common.c:1028:6: warning: variable
'ret' set but not used [-Wunused-but-set-variable]
int ret = 0;
^
1 warning generated.

The return code of this function has never been checked so just remove
ret and make the function return void.

Fixes: 3ba81f3ece3c ("net: Micrel KS8851 SPI network driver")
Suggested-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

of: net: pass the dst buffer to of_get_mac_address()

of_get_mac_address() returns a "const void*" pointer to a MAC address.
Lately, support to fetch the MAC address by an NVMEM provider was added.
But this will only work with platform devices. It will not work with
PCI devices (e.g. of an integrated root complex) and esp. not with DSA
ports.

There is an of_* variant of the nvmem binding which works without
devices. The returned data of a nvmem_cell_read() has to be freed after
use. On the other hand the return of_get_mac_address() points to some
static data without a lifetime. The trick for now, was to allocate a
device resource managed buffer which is then returned. This will only
work if we have an actual device.

Change it, so that the caller of of_get_mac_address() has to supply a
buffer where the MAC address is written to. Unfortunately, this will
touch all drivers which use the of_get_mac_address().

Usually the code looks like:

const char *addr;
addr = of_get_mac_address(np);
if (!IS_ERR(addr))
ether_addr_copy(ndev->dev_addr, addr);

This can then be simply rewritten as:

of_get_mac_address(np, ndev->dev_addr);

Sometimes is_valid_ether_addr() is used to test the MAC address.
of_get_mac_address() already makes sure, it just returns a valid MAC
address. Thus we can just test its return code. But we have to be
careful if there are still other sources for the MAC address before the
of_get_mac_address(). In this case we have to keep the
is_valid_ether_addr() call.

The following coccinelle patch was used to convert common cases to the
new style. Afterwards, I've manually gone over the drivers and fixed the
return code variable: either used a new one or if one was already
available use that. Mansour Moufid, thanks for that coccinelle patch!

<spml>
@a@
identifier x;
expression y, z;
@@
- x = of_get_mac_address(y);
+ x = of_get_mac_address(y, z);
<...
- ether_addr_copy(z, x);
...>

@@
identifier a.x;
@@
- if (<+... x ...+>) {}

@@
identifier a.x;
@@
if (<+... x ...+>) {
...
}
- else {}

@@
identifier a.x;
expression e;
@@
- if (<+... x ...+>@e)
- {}
- else
+ if (!(e))
{...}

@@
expression x, y, z;
@@
- x = of_get_mac_address(y, z);
+ of_get_mac_address(y, z);
... when != x
</spml>

All drivers, except drivers/net/ethernet/aeroflex/greth.c, were
compile-time tested.

Suggested-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: ks8851: remove definition of DEBUG

Defining DEBUG should only be done in development.
So remove DEBUG.

Signed-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Link: https://lore.kernel.org/r/20210115153128.131026-1-trix@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: ks8851: Register MDIO bus and the internal PHY

The KS8851 has a reduced internal PHY, which is accessible through its
registers at offset 0xe4. The PHY is compatible with KS886x PHY present
in Micrel switches, except the PHY ID Low/High registers are swapped.
Register MDIO bus so this PHY can be detected and probed by phylib.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Heiner Kallweit <hkallweit1@gmail.com>
Cc: Lukas Wunner <lukas@wunner.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: micrel: convert comma to semicolon

Replace a comma between expression statements by a semicolon.

Signed-off-by: Zheng Yongjun <zhengyongjun3@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: ks8851: Separate SPI operations into separate file

Pull all the SPI bus specific code into a separate file, so that it is
not mixed with the common code. Rename ks8851.c to ks8851_common.c. The
ks8851_common.c is linked with ks8851_spi.c now, so it can call the
accessors in the ks8851_spi.c without any pointer indirection.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: David S. Miller <davem@davemloft.net>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Petr Stetiar <ynezz@true.cz>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>