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authorMing Lei <ming.lei@redhat.com>2024-01-12 15:00:00 +0800
committerMartin K. Petersen <martin.petersen@oracle.com>2024-01-23 21:21:51 -0500
commit4373534a9850627a2695317944898eb1283a2db0 (patch)
treef0ab8a62adb4aeb9a74b8300ab0f29d600988862 /drivers/scsi
parent52998cdd8d3438df9a77c858a827b8932da1bb28 (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')
-rw-r--r--drivers/scsi/scsi_error.c8
-rw-r--r--drivers/scsi/scsi_lib.c2
-rw-r--r--drivers/scsi/scsi_priv.h2
3 files changed, 6 insertions, 6 deletions
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 79da4b1c1df0..4f455884fdc4 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -61,11 +61,11 @@ static int scsi_eh_try_stu(struct scsi_cmnd *scmd);
static enum scsi_disposition scsi_try_to_abort_cmd(const struct scsi_host_template *,
struct scsi_cmnd *);
-void scsi_eh_wakeup(struct Scsi_Host *shost)
+void scsi_eh_wakeup(struct Scsi_Host *shost, unsigned int busy)
{
lockdep_assert_held(shost->host_lock);
- if (scsi_host_busy(shost) == shost->host_failed) {
+ if (busy == shost->host_failed) {
trace_scsi_eh_wakeup(shost);
wake_up_process(shost->ehandler);
SCSI_LOG_ERROR_RECOVERY(5, shost_printk(KERN_INFO, shost,
@@ -88,7 +88,7 @@ void scsi_schedule_eh(struct Scsi_Host *shost)
if (scsi_host_set_state(shost, SHOST_RECOVERY) == 0 ||
scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY) == 0) {
shost->host_eh_scheduled++;
- scsi_eh_wakeup(shost);
+ scsi_eh_wakeup(shost, scsi_host_busy(shost));
}
spin_unlock_irqrestore(shost->host_lock, flags);
@@ -286,7 +286,7 @@ static void scsi_eh_inc_host_failed(struct rcu_head *head)
spin_lock_irqsave(shost->host_lock, flags);
shost->host_failed++;
- scsi_eh_wakeup(shost);
+ scsi_eh_wakeup(shost, scsi_host_busy(shost));
spin_unlock_irqrestore(shost->host_lock, flags);
}
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index cf3864f72093..1fb80eae9a63 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -280,7 +280,7 @@ static void scsi_dec_host_busy(struct Scsi_Host *shost, struct scsi_cmnd *cmd)
if (unlikely(scsi_host_in_recovery(shost))) {
spin_lock_irqsave(shost->host_lock, flags);
if (shost->host_failed || shost->host_eh_scheduled)
- scsi_eh_wakeup(shost);
+ scsi_eh_wakeup(shost, scsi_host_busy(shost));
spin_unlock_irqrestore(shost->host_lock, flags);
}
rcu_read_unlock();
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,