linux-kernel - Re: [RESEND] mmc: core: Fix system shutdown hang in mmc_bus

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Message-ID: <CACRpkdbQH2+AoCVAZf_apQ=uhkbinkHtk60ssB0ODpBZY-gATw@mail.gmail.com>
Date: Wed, 15 Oct 2025 08:30:13 +0200
From: Linus Walleij <linus.walleij@...aro.org>
To: Michael Wu <michael@...winnertech.com>
Cc: ulf.hansson@...aro.org, brgl@...ev.pl, adrian.hunter@...el.com, 
	avri.altman@....com, wsa+renesas@...g-engineering.com, 
	victor.shih@...esyslogic.com.tw, andy-ld.lu@...iatek.com, 
	jason.lai@...esyslogic.com.tw, linux-mmc@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org
Subject: Re: [RESEND] mmc: core: Fix system shutdown hang in mmc_bus_shutdown

Hi Michael,

thanks for your patch!

On Wed, Oct 15, 2025 at 8:07 AM Michael Wu <michael@...winnertech.com> wrote:

> During system shutdown, mmc_bus_shutdown() calls __mmc_stop_host() which
> uses cancel_delayed_work_sync(). This can block indefinitely if the work
> queue is stuck, causing the system to hang during shutdown.
>
> This patch introduces a new function __mmc_stop_host_no_sync() that skips
> the synchronous work cancellation, preventing potential shutdown hangs.
> The function is used in mmc_bus_shutdown() where blocking is not
> acceptable during system shutdown.
>
> Changes:
> - Add __mmc_stop_host_no_sync() function that avoids cancel_delayed_work_sync()

Why is this function prefixed with __two underscores? The
__mmc_stop_host is named like that because there is another
function with the same name, but here is no mmc_stop_host_no_sync()
so just name it without underscores.

Yours,
Linus Walleij