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    Subject[PATCH AUTOSEL 5.10 30/93] scsi: mpt3sas: Fix deadlock while cancelling the running firmware event
    Date
    From: Suganath Prabu S <suganath-prabu.subramani@broadcom.com>

    [ Upstream commit e2fac6c44ae06e58ac02181b048af31195883c31 ]

    Do not cancel current running firmware event work if the event type is
    different from MPT3SAS_REMOVE_UNRESPONDING_DEVICES. Otherwise a deadlock
    can be observed while cancelling the current firmware event work if a hard
    reset operation is called as part of processing the current event.

    Link: https://lore.kernel.org/r/20210518051625.1596742-2-suganath-prabu.subramani@broadcom.com
    Signed-off-by: Suganath Prabu S <suganath-prabu.subramani@broadcom.com>
    Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/scsi/mpt3sas/mpt3sas_scsih.c | 22 ++++++++++++++++++++++
    1 file changed, 22 insertions(+)

    diff --git a/drivers/scsi/mpt3sas/mpt3sas_scsih.c b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
    index 5f845d7094fc..738b71653e9c 100644
    --- a/drivers/scsi/mpt3sas/mpt3sas_scsih.c
    +++ b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
    @@ -3526,6 +3526,28 @@ _scsih_fw_event_cleanup_queue(struct MPT3SAS_ADAPTER *ioc)
    ioc->fw_events_cleanup = 1;
    while ((fw_event = dequeue_next_fw_event(ioc)) ||
    (fw_event = ioc->current_event)) {
    +
    + /*
    + * Don't call cancel_work_sync() for current_event
    + * other than MPT3SAS_REMOVE_UNRESPONDING_DEVICES;
    + * otherwise we may observe deadlock if current
    + * hard reset issued as part of processing the current_event.
    + *
    + * Orginal logic of cleaning the current_event is added
    + * for handling the back to back host reset issued by the user.
    + * i.e. during back to back host reset, driver use to process
    + * the two instances of MPT3SAS_REMOVE_UNRESPONDING_DEVICES
    + * event back to back and this made the drives to unregister
    + * the devices from SML.
    + */
    +
    + if (fw_event == ioc->current_event &&
    + ioc->current_event->event !=
    + MPT3SAS_REMOVE_UNRESPONDING_DEVICES) {
    + ioc->current_event = NULL;
    + continue;
    + }
    +
    /*
    * Wait on the fw_event to complete. If this returns 1, then
    * the event was never executed, and we need a put for the
    --
    2.30.2
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