netdev - Re: [PATCH net] net: wireless: marvell: mwifiex: fix sleep in atomic context bugs

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Message-ID: <87fsl53jic.fsf@kernel.org>
Date:   Thu, 19 May 2022 13:27:07 +0300
From:   Kalle Valo <kvalo@...nel.org>
To:     Duoming Zhou <duoming@....edu.cn>
Cc:     linux-kernel@...r.kernel.org, amitkarwar@...il.com,
        ganapathi017@...il.com, sharvari.harisangam@....com,
        huxinming820@...il.com, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH net] net: wireless: marvell: mwifiex: fix sleep in atomic context bugs

Duoming Zhou <duoming@....edu.cn> writes:

> There are sleep in atomic context bugs when uploading device dump
> data on usb interface. The root cause is that the operations that
> may sleep are called in fw_dump_timer_fn which is a timer handler.
> The call tree shows the execution paths that could lead to bugs:
>
>    (Interrupt context)
> fw_dump_timer_fn
>   mwifiex_upload_device_dump
>     dev_coredumpv(..., GFP_KERNEL)
>       dev_coredumpm()
>         kzalloc(sizeof(*devcd), gfp); //may sleep
>         dev_set_name
>           kobject_set_name_vargs
>             kvasprintf_const(GFP_KERNEL, ...); //may sleep
>             kstrdup(s, GFP_KERNEL); //may sleep
>
> This patch moves the operations that may sleep into a work item.
> The work item will run in another kernel thread which is in
> process context to execute the bottom half of the interrupt.
> So it could prevent atomic context from sleeping.
>
> Fixes: f5ecd02a8b20 ("mwifiex: device dump support for usb interface")
> Signed-off-by: Duoming Zhou <duoming@....edu.cn>

Have you tested this on real hardware? Or is this just a theoretical
fix?

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