[added to the 4.1 stable tree] scsi: hpsa: limit outstanding rescans

[Sasha Levin <Alexander.Levin@xxxxxxxxxxxxx>]

From: Don Brace <don.brace@xxxxxxxxxxxxx>

This patch has been added to the  stable tree. If you have any
objections, please let us know.

===============

[ Upstream commit 87b9e6aa87d9411f1059aa245c0c79976bc557ac ]

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

Reviewed-by: Scott Benesh <scott.benesh@xxxxxxxxxxxxx>
Reviewed-by: Scott Teel <scott.teel@xxxxxxxxxxxxx>
Reviewed-by: Tomas Henzl <thenzl@xxxxxxxxxx>
Signed-off-by: Don Brace <don.brace@xxxxxxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
 drivers/scsi/hpsa.c | 16 +++++++++++++++-
 drivers/scsi/hpsa.h |  1 +
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c
index 8eab107b53fb..0ef5d9286e0a 100644
--- a/drivers/scsi/hpsa.c
+++ b/drivers/scsi/hpsa.c
@@ -4158,7 +4158,7 @@ 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);
 }
 
@@ -4176,11 +4176,23 @@ 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
@@ -4190,6 +4202,7 @@ 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)))
@@ -6936,6 +6949,7 @@ static int hpsa_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 		goto clean4;
 	init_waitqueue_head(&h->scan_wait_queue);
 	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 657713050349..cbaf416d5456 100644
--- a/drivers/scsi/hpsa.h
+++ b/drivers/scsi/hpsa.h
@@ -166,6 +166,7 @@ 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;
 
-- 
2.11.0