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

Don Brace
2017-03-10T20:35:37Z

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> review
Signed-off-by: Don Brace <don.brace@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;