Just found Andrei Warkentin also submitted a RFC patch, which included more fix for mounted root file system media. Please ignore this thread. > -----Original Message----- > From: linux-mmc-owner@xxxxxxxxxxxxxxx > [mailto:linux-mmc-owner@xxxxxxxxxxxxxxx] On Behalf Of Chuanxiao Dong > Sent: Tuesday, May 17, 2011 3:54 PM > To: linux-mmc@xxxxxxxxxxxxxxx > Cc: He, Bo > Subject: [RFC]mmc: fix dead lock issue when system entering S3 > > Hi all, > I encountered a dead lock issue. Two threads try to claim host, unfortunately > one thread needs to sync with the other. I encountered this issue with SD > card when testing system entering S3. Does anybody encounter the same > issue? > > Environment: > 1. without CONFIG_MMC_UNSAFE_RESUME operation > 2. the SD card mounted > > During system tried to enter S3, mmc_pm_notifier will be called first to remove > SD card. So calling sequence in SD remove thread is like this: > mmc_claim_host > bus_ops->remove > .... > .... > mmc_cleanup_queue > kthread_stop(mq->thread) > ... > ... > > Mean while, mmc_cleanup_queue wakes up mq->thread, the calling sequence in > mq->thread is > like this: > mmc_queue_thread > mq->issue_fn (mmc_blk_issue_rq) > mmc_claim_host (dead lock) > .... > .... > > Since mmc_claim_host is called in mq->thread (not SD remove thread) again, > unfortunately right now host is already claimed by SD remove thread which is > also waiting for mq->thread finished, so cause a dead lock here. > > Move the mmc_claim_host(in mmc_pm_notifier) after bus_ops->remove can > resolve > this dead lock. mmc_suspend_host() is using the same way to claim host. > > Need to know your suggestions. > > Signed-off-by: He Bo <bo.he@xxxxxxxxx> > Signed-off-by: Chuanxiao Dong <chuanxiao.dong@xxxxxxxxx> > --- > drivers/mmc/core/core.c | 3 +-- > 1 files changed, 1 insertions(+), 2 deletions(-) > > diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c > index 68091dd..1e27588 100644 > --- a/drivers/mmc/core/core.c > +++ b/drivers/mmc/core/core.c > @@ -1850,11 +1850,10 @@ int mmc_pm_notify(struct notifier_block > *notify_block, > if (!host->bus_ops || host->bus_ops->suspend) > break; > > - mmc_claim_host(host); > - > if (host->bus_ops->remove) > host->bus_ops->remove(host); > > + mmc_claim_host(host); > mmc_detach_bus(host); > mmc_release_host(host); > host->pm_flags = 0; > -- > 1.7.3.4 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-mmc" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
