[PATCH V3 2/3] hpsa: limit outstanding rescans

[Don Brace]

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

Reviewed-by: Scott Benesh <scott.ben...@microsemi.com>
Reviewed-by: Scott Teel <scott.t...@microsemi.com>
Reviewed-by: Tomas Henzl <the...@redhat.com> review
Signed-off-by: Don Brace <don.br...@microsemi.com>
---
 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 90b76c4..0a8ac68 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 @@ static int hpsa_init_one(struct pci_dev *pdev, const 
struct pci_device_id *ent)
        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 bf6cdc1..6f04f2a 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;