Re: [PATCH] MMC: Fix race condition in resume/card detect code

From: Pierre Ossman
Date: Sat Oct 18 2008 - 13:12:11 EST

On Thu, 16 Oct 2008 19:09:36 +0300
Yauhen Kharuzhy <jekhor@xxxxxxxxx> wrote:

> When device wakes up by card change interrupt and MMC_UNSAFE_RESUME is
> enabled then race condition between mmc_rescan() and
> mmc_resume()/mmc_sd_resume() appeared.
> Resume functions can sleep into mmc_remove_card() and at this time
> mmc_rescan() can be called by delayed work handler. Double-free of
> kobject or double-remove of host->card can be result of this.
> This patch adds an mutex which deny simultaneous executing of
> mmc_sd_resume()/mmc_resume() and mmc_rescan() functions. Probably, it is
> not right way.
> Signed-off-by: Yauhen Kharuzhy <jekhor@xxxxxxxxx>
> ---

Can't we just ask the PM layer if this device is currently resuming,
and if so ignore card notifications from the driver?

-- Pierre Ossman

Linux kernel, MMC maintainer
rdesktop, core developer

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