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

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Message-ID: <257f8e7.216cd.180dc1af4d3.Coremail.duoming@zju.edu.cn>
Date:   Thu, 19 May 2022 19:36:35 +0800 (GMT+08:00)
From:   duoming@....edu.cn
To:     "Kalle Valo" <kvalo@...nel.org>
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

Hello,

On Thu, 19 May 2022 13:27:07 +0300 Kalle Valo wrote:

> > 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?

This is a theoretical fix. I don't have the real hardware.

Best regards,
Duoming Zhou