diff options
| author | Ming Lei <ming.lei@redhat.com> | 2024-01-12 15:00:00 +0800 |
|---|---|---|
| committer | Martin K. Petersen <martin.petersen@oracle.com> | 2024-01-23 21:21:51 -0500 |
| commit | 4373534a9850627a2695317944898eb1283a2db0 (patch) | |
| tree | f0ab8a62adb4aeb9a74b8300ab0f29d600988862 /drivers/scsi/scsi_priv.h | |
| parent | 52998cdd8d3438df9a77c858a827b8932da1bb28 (diff) | |
scsi: core: Move scsi_host_busy() out of host lock for waking up EH handler
Inside scsi_eh_wakeup(), scsi_host_busy() is called & checked with host
lock every time for deciding if error handler kthread needs to be waken up.
This can be too heavy in case of recovery, such as:
- N hardware queues
- queue depth is M for each hardware queue
- each scsi_host_busy() iterates over (N * M) tag/requests
If recovery is triggered in case that all requests are in-flight, each
scsi_eh_wakeup() is strictly serialized, when scsi_eh_wakeup() is called
for the last in-flight request, scsi_host_busy() has been run for (N * M -
1) times, and request has been iterated for (N*M - 1) * (N * M) times.
If both N and M are big enough, hard lockup can be triggered on acquiring
host lock, and it is observed on mpi3mr(128 hw queues, queue depth 8169).
Fix the issue by calling scsi_host_busy() outside the host lock. We don't
need the host lock for getting busy count because host the lock never
covers that.
[mkp: Drop unnecessary 'busy' variables pointed out by Bart]
Cc: Ewan Milne <emilne@redhat.com>
Fixes: 6eb045e092ef ("scsi: core: avoid host-wide host_busy counter for scsi_mq")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20240112070000.4161982-1-ming.lei@redhat.com
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Reviewed-by: Sathya Prakash Veerichetty <safhya.prakash@broadcom.com>
Tested-by: Sathya Prakash Veerichetty <safhya.prakash@broadcom.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/scsi/scsi_priv.h')
| -rw-r--r-- | drivers/scsi/scsi_priv.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/scsi/scsi_priv.h b/drivers/scsi/scsi_priv.h index 3f0dfb97db6b..1fbfe1b52c9f 100644 --- a/drivers/scsi/scsi_priv.h +++ b/drivers/scsi/scsi_priv.h @@ -92,7 +92,7 @@ extern void scmd_eh_abort_handler(struct work_struct *work); extern enum blk_eh_timer_return scsi_timeout(struct request *req); extern int scsi_error_handler(void *host); extern enum scsi_disposition scsi_decide_disposition(struct scsi_cmnd *cmd); -extern void scsi_eh_wakeup(struct Scsi_Host *shost); +extern void scsi_eh_wakeup(struct Scsi_Host *shost, unsigned int busy); extern void scsi_eh_scmd_add(struct scsi_cmnd *); void scsi_eh_ready_devs(struct Scsi_Host *shost, struct list_head *work_q, |