lkml.org 
[lkml]   [2020]   [May]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH V2] mmc: core: Fix recursive locking issue in CQE recovery path
    From
    Date
    On 7/05/20 7:15 pm, Veerabhadrarao Badiganti wrote:
    > From: Sarthak Garg <sartgarg@codeaurora.org>
    >
    > Consider the following stack trace
    >
    > -001|raw_spin_lock_irqsave
    > -002|mmc_blk_cqe_complete_rq
    > -003|__blk_mq_complete_request(inline)
    > -003|blk_mq_complete_request(rq)
    > -004|mmc_cqe_timed_out(inline)
    > -004|mmc_mq_timed_out
    >
    > mmc_mq_timed_out acquires the queue_lock for the first
    > time. The mmc_blk_cqe_complete_rq function also tries to acquire
    > the same queue lock resulting in recursive locking where the task
    > is spinning for the same lock which it has already acquired leading
    > to watchdog bark.
    >
    > Fix this issue with the lock only for the required critical section.
    >
    > Cc: <stable@vger.kernel.org>
    > Fixes: 1e8e55b67030 ("mmc: block: Add CQE support")
    > Suggested-by: Sahitya Tummala <stummala@codeaurora.org>
    > Signed-off-by: Sarthak Garg <sartgarg@codeaurora.org>

    Acked-by: Adrian Hunter <adrian.hunter@intel.com>

    > ---
    > drivers/mmc/core/queue.c | 13 ++++---------
    > 1 file changed, 4 insertions(+), 9 deletions(-)
    >
    > diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c
    > index 25bee3d..b5fd3bc 100644
    > --- a/drivers/mmc/core/queue.c
    > +++ b/drivers/mmc/core/queue.c
    > @@ -107,7 +107,7 @@ static enum blk_eh_timer_return mmc_cqe_timed_out(struct request *req)
    > case MMC_ISSUE_DCMD:
    > if (host->cqe_ops->cqe_timeout(host, mrq, &recovery_needed)) {
    > if (recovery_needed)
    > - __mmc_cqe_recovery_notifier(mq);
    > + mmc_cqe_recovery_notifier(mrq);
    > return BLK_EH_RESET_TIMER;
    > }
    > /* No timeout (XXX: huh? comment doesn't make much sense) */
    > @@ -127,18 +127,13 @@ static enum blk_eh_timer_return mmc_mq_timed_out(struct request *req,
    > struct mmc_card *card = mq->card;
    > struct mmc_host *host = card->host;
    > unsigned long flags;
    > - int ret;
    > + bool ignore_tout;
    >
    > spin_lock_irqsave(&mq->lock, flags);
    > -
    > - if (mq->recovery_needed || !mq->use_cqe || host->hsq_enabled)
    > - ret = BLK_EH_RESET_TIMER;
    > - else
    > - ret = mmc_cqe_timed_out(req);
    > -
    > + ignore_tout = mq->recovery_needed || !mq->use_cqe || host->hsq_enabled;
    > spin_unlock_irqrestore(&mq->lock, flags);
    >
    > - return ret;
    > + return ignore_tout ? BLK_EH_RESET_TIMER : mmc_cqe_timed_out(req);
    > }
    >
    > static void mmc_mq_recovery_handler(struct work_struct *work)
    >

    \
     
     \ /
      Last update: 2020-05-07 19:23    [W:3.696 / U:0.240 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site