scsi: core: Move scsi_host_busy() out of host lock if it is for per-command

Commit 4373534 ("scsi: core: Move scsi_host_busy() out of host lock
for waking up EH handler") intended to fix a hard lockup issue triggered by
EH. The core idea was to move scsi_host_busy() out of the host lock when
processing individual commands for EH. However, a suggested style change
inadvertently caused scsi_host_busy() to remain under the host lock. Fix
this by calling scsi_host_busy() outside the lock.

Fixes: 4373534 ("scsi: core: Move scsi_host_busy() out of host lock for waking up EH handler")
Cc: Sathya Prakash Veerichetty <safhya.prakash@broadcom.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Ewan D. Milne <emilne@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20240203024521.2006455-1-ming.lei@redhat.com
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: Ming Lei

drivers/scsi/scsi_error.c

@@ -282,11 +282,12 @@ static void scsi_eh_inc_host_failed(struct rcu_head *head)
 {
 	struct scsi_cmnd *scmd = container_of(head, typeof(*scmd), rcu);
 	struct Scsi_Host *shost = scmd->device->host;
+	unsigned int busy = scsi_host_busy(shost);
 	unsigned long flags;
 
 	spin_lock_irqsave(shost->host_lock, flags);
 	shost->host_failed++;
-	scsi_eh_wakeup(shost, scsi_host_busy(shost));
+	scsi_eh_wakeup(shost, busy);
 	spin_unlock_irqrestore(shost->host_lock, flags);
 }
 

drivers/scsi/scsi_lib.c

@@ -278,9 +278,11 @@ static void scsi_dec_host_busy(struct Scsi_Host *shost, struct scsi_cmnd *cmd)
 	rcu_read_lock();
 	__clear_bit(SCMD_STATE_INFLIGHT, &cmd->state);
 	if (unlikely(scsi_host_in_recovery(shost))) {
+		unsigned int busy = scsi_host_busy(shost);
+
 		spin_lock_irqsave(shost->host_lock, flags);
 		if (shost->host_failed || shost->host_eh_scheduled)
-			scsi_eh_wakeup(shost, scsi_host_busy(shost));
+			scsi_eh_wakeup(shost, busy);
 		spin_unlock_irqrestore(shost->host_lock, flags);
 	}
 	rcu_read_unlock();