lkml.org 
[lkml]   [2012]   [Oct]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[ 103/180] SCSI: fix eh wakeup (scsi_schedule_eh vs scsi_restart_operations)
    2.6.32-longterm review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Dan Williams <dan.j.williams@intel.com>

    commit 57fc2e335fd3c2f898ee73570dc81426c28dc7b4 upstream.

    Rapid ata hotplug on a libsas controller results in cases where libsas
    is waiting indefinitely on eh to perform an ata probe.

    A race exists between scsi_schedule_eh() and scsi_restart_operations()
    in the case when scsi_restart_operations() issues i/o to other devices
    in the sas domain. When this happens the host state transitions from
    SHOST_RECOVERY (set by scsi_schedule_eh) back to SHOST_RUNNING and
    ->host_busy is non-zero so we put the eh thread to sleep even though
    ->host_eh_scheduled is active.

    Before putting the error handler to sleep we need to check if the
    host_state needs to return to SHOST_RECOVERY for another trip through
    eh. Since i/o that is released by scsi_restart_operations has been
    blocked for at least one eh cycle, this implementation allows those
    i/o's to run before another eh cycle starts to discourage hung task
    timeouts.

    Reported-by: Tom Jackson <thomas.p.jackson@intel.com>
    Tested-by: Tom Jackson <thomas.p.jackson@intel.com>
    Signed-off-by: Dan Williams <dan.j.williams@intel.com>
    Signed-off-by: James Bottomley <JBottomley@Parallels.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: Willy Tarreau <w@1wt.eu>
    ---
    drivers/scsi/scsi_error.c | 14 ++++++++++++++
    1 files changed, 14 insertions(+), 0 deletions(-)

    diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
    index 573921d..3890793 100644
    --- a/drivers/scsi/scsi_error.c
    +++ b/drivers/scsi/scsi_error.c
    @@ -1550,6 +1550,20 @@ static void scsi_restart_operations(struct Scsi_Host *shost)
    * requests are started.
    */
    scsi_run_host_queues(shost);
    +
    + /*
    + * if eh is active and host_eh_scheduled is pending we need to re-run
    + * recovery. we do this check after scsi_run_host_queues() to allow
    + * everything pent up since the last eh run a chance to make forward
    + * progress before we sync again. Either we'll immediately re-run
    + * recovery or scsi_device_unbusy() will wake us again when these
    + * pending commands complete.
    + */
    + spin_lock_irqsave(shost->host_lock, flags);
    + if (shost->host_eh_scheduled)
    + if (scsi_host_set_state(shost, SHOST_RECOVERY))
    + WARN_ON(scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY));
    + spin_unlock_irqrestore(shost->host_lock, flags);
    }

    /**
    --
    1.7.2.1.45.g54fbc




    \
     
     \ /
      Last update: 2012-10-02 10:41    [W:4.182 / U:0.772 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site