scsi: hpsa: limit outstanding rescans

Avoid rescan storms. No need to queue another if one is pending.

Reviewed-by: Scott Benesh <scott.benesh@microsemi.com>
Reviewed-by: Scott Teel <scott.teel@microsemi.com>
Reviewed-by: Tomas Henzl <thenzl@redhat.com>
Signed-off-by: Don Brace <don.brace@microsemi.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

2 files changed, 16 insertions, 1 deletions

diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c
index 90b76c4c6d36..0a8ac68f4ca1 100644
--- a/drivers/scsi/hpsa.c
+++ b/drivers/scsi/hpsa.c
@@ -5555,7 +5555,7 @@ static void hpsa_scan_complete(struct ctlr_info *h)
 
         spin_lock_irqsave(&h->scan_lock, flags);
         h->scan_finished = 1;
-        wake_up_all(&h->scan_wait_queue);
+        wake_up(&h->scan_wait_queue);
         spin_unlock_irqrestore(&h->scan_lock, flags);
 }
 
@@ -5573,11 +5573,23 @@ static void hpsa_scan_start(struct Scsi_Host *sh)
         if (unlikely(lockup_detected(h)))
                 return hpsa_scan_complete(h);
 
+        /*
+         * If a scan is already waiting to run, no need to add another
+         */
+        spin_lock_irqsave(&h->scan_lock, flags);
+        if (h->scan_waiting) {
+                spin_unlock_irqrestore(&h->scan_lock, flags);
+                return;
+        }
+
+        spin_unlock_irqrestore(&h->scan_lock, flags);
+
         /* wait until any scan already in progress is finished. */
         while (1) {
                 spin_lock_irqsave(&h->scan_lock, flags);
                 if (h->scan_finished)
                         break;
+                h->scan_waiting = 1;
                 spin_unlock_irqrestore(&h->scan_lock, flags);
                 wait_event(h->scan_wait_queue, h->scan_finished);
                 /* Note: We don't need to worry about a race between this
@@ -5587,6 +5599,7 @@ static void hpsa_scan_start(struct Scsi_Host *sh)
                  */
         }
         h->scan_finished = 0; /* mark scan as in progress */
+        h->scan_waiting = 0;
         spin_unlock_irqrestore(&h->scan_lock, flags);
 
         if (unlikely(lockup_detected(h)))
@@ -8789,6 +8802,7 @@ reinit_after_soft_reset:
         init_waitqueue_head(&h->event_sync_wait_queue);
         mutex_init(&h->reset_mutex);
         h->scan_finished = 1; /* no scan currently in progress */
+        h->scan_waiting = 0;
 
         pci_set_drvdata(pdev, h);
         h->ndevices = 0;
diff --git a/drivers/scsi/hpsa.h b/drivers/scsi/hpsa.h
index bf6cdc106654..6f04f2ad4125 100644
--- a/drivers/scsi/hpsa.h
+++ b/drivers/scsi/hpsa.h
@@ -201,6 +201,7 @@ struct ctlr_info {
         dma_addr_t              errinfo_pool_dhandle;
         unsigned long           *cmd_pool_bits;
         int                     scan_finished;
+        u8                      scan_waiting : 1;
         spinlock_t              scan_lock;
         wait_queue_head_t       scan_wait_queue;