Messages in this thread | | | Date | Mon, 20 Oct 2008 22:47:40 +0200 | From | "J.A. Magallón" <> | Subject | Re: [PATCH] MMC: Fix race condition in resume/card detect code |
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On Mon, 20 Oct 2008 22:41:48 +0300, Yauhen Kharuzhy <jekhor@gmail.com> 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 host->suspended flag which indicated that host is in > suspend state. mmc_rescan() checks it and returned when > host->suspended == 1. It's safe because resume code calls > mmc_detect_change() at end of resume process. > > Signed-off-by: Yauhen Kharuzhy <jekhor@gmail.com> > --- > drivers/mmc/core/core.c | 7 +++++++ > include/linux/mmc/host.h | 3 +++ > 2 files changed, 10 insertions(+), 0 deletions(-) > > diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c > index 044d84e..427f283 100644 > --- a/drivers/mmc/core/core.c > +++ b/drivers/mmc/core/core.c > @@ -657,6 +657,9 @@ void mmc_rescan(struct work_struct *work) > u32 ocr; > int err; > > + if (host->suspended) > + return; > + > mmc_bus_get(host); > > if (host->bus_ops == NULL) { > @@ -780,6 +783,8 @@ int mmc_suspend_host(struct mmc_host *host, pm_message_t state) > > mmc_power_off(host); > > + host->suspended = 1; > + > return 0; > } > > @@ -805,6 +810,8 @@ int mmc_resume_host(struct mmc_host *host) > */ > mmc_detect_change(host, 1); > > + host->suspended = 0; > + > return 0; > } > > diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h > index 9c288c9..a584239 100644 > --- a/include/linux/mmc/host.h > +++ b/include/linux/mmc/host.h > @@ -139,6 +139,9 @@ struct mmc_host { > #ifdef CONFIG_MMC_DEBUG > unsigned int removed:1; /* host is being removed */ > #endif > +#ifdef CONFIG_MMC_UNSAFE_RESUME > + unsigned int suspended:1; > +#endif > > struct mmc_card *card; /* device attached to this host */ >
Shouldn't you also bracket any acces to ->suspended with the ifdefs ? Compilation failed on my box...and I had to enable MMC_UNSAFE_RESUME.
-- J.A. Magallon <jamagallon()ono!com> \ Software is like sex: \ It's better when it's free Mandriva Linux release 2009.0 (Cooker) for i586 Linux 2.6.25-jam18 (gcc 4.3.1 20080626 (GCC) #1 SMP
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