netdev - Re: [PATCH net v2] net: stmmac: remove unneeded stmmac_poll

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Date: Thu, 07 Sep 2023 11:23:16 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: Remi Pommarel <repk@...plefau.lt>, Alexandre Torgue
 <alexandre.torgue@...s.st.com>, Jose Abreu <joabreu@...opsys.com>, "David
 S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Jakub
 Kicinski <kuba@...nel.org>,  Maxime Coquelin <mcoquelin.stm32@...il.com>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
	stable@...r.kernel.org
Subject: Re: [PATCH net v2] net: stmmac: remove unneeded
 stmmac_poll_controller

On Wed, 2023-09-06 at 11:13 +0200, Remi Pommarel wrote:
> Using netconsole netpoll_poll_dev could be called from interrupt
> context, thus using disable_irq() would cause the following kernel
> warning with CONFIG_DEBUG_ATOMIC_SLEEP enabled:
> 
>   BUG: sleeping function called from invalid context at kernel/irq/manage.c:137
>   in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 10, name: ksoftirqd/0
>   CPU: 0 PID: 10 Comm: ksoftirqd/0 Tainted: G        W         5.15.42-00075-g816b502b2298-dirty #117
>   Hardware name: aml (r1) (DT)
>   Call trace:
>    dump_backtrace+0x0/0x270
>    show_stack+0x14/0x20
>    dump_stack_lvl+0x8c/0xac
>    dump_stack+0x18/0x30
>    ___might_sleep+0x150/0x194
>    __might_sleep+0x64/0xbc
>    synchronize_irq+0x8c/0x150
>    disable_irq+0x2c/0x40
>    stmmac_poll_controller+0x140/0x1a0
>    netpoll_poll_dev+0x6c/0x220
>    netpoll_send_skb+0x308/0x390
>    netpoll_send_udp+0x418/0x760
>    write_msg+0x118/0x140 [netconsole]
>    console_unlock+0x404/0x500
>    vprintk_emit+0x118/0x250
>    dev_vprintk_emit+0x19c/0x1cc
>    dev_printk_emit+0x90/0xa8
>    __dev_printk+0x78/0x9c
>    _dev_warn+0xa4/0xbc
>    ath10k_warn+0xe8/0xf0 [ath10k_core]
>    ath10k_htt_txrx_compl_task+0x790/0x7fc [ath10k_core]
>    ath10k_pci_napi_poll+0x98/0x1f4 [ath10k_pci]
>    __napi_poll+0x58/0x1f4
>    net_rx_action+0x504/0x590
>    _stext+0x1b8/0x418
>    run_ksoftirqd+0x74/0xa4
>    smpboot_thread_fn+0x210/0x3c0
>    kthread+0x1fc/0x210
>    ret_from_fork+0x10/0x20
> 
> Since [0] .ndo_poll_controller is only needed if driver doesn't or
> partially use NAPI. Because stmmac does so, stmmac_poll_controller
> can be removed fixing the above warning.
> 
> [0] commit ac3d9dd034e5 ("netpoll: make ndo_poll_controller() optional")
> 
> Cc: <stable@...r.kernel.org> # 5.15.x
> Signed-off-by: Remi Pommarel <repk@...plefau.lt>

I'm sorry for the incremental feedback, but we also need a suitable
Fixes tag, thanks!

Paolo