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

[Tomas Henzl]

On 6.3.2017 22:24, Don Brace wrote:
> avoid rescan storms. No need to queue another
> if one is pending.
>
> Reviewed-by: Scott Benesh 
> Reviewed-by: Scott Teel 
> Signed-off-by: Don Brace 
> ---
>  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 1adc4ec..a36d3a6 100644
> --- a/drivers/scsi/hpsa.c
> +++ b/drivers/scsi/hpsa.c
> @@ -5558,7 +5558,7 @@ static void hpsa_scan_complete(struct ctlr_info *h)
>  
>   spin_lock_irqsave(>scan_lock, flags);
>   h->scan_finished = 1;
> - wake_up_all(>scan_wait_queue);
> + wake_up(>scan_wait_queue);
>   spin_unlock_irqrestore(>scan_lock, flags);
>  }
>  
> @@ -5576,11 +5576,23 @@ static void hpsa_scan_start(struct Scsi_Host *sh)
>   if (unlikely(lockup_detected(h)))
>   return hpsa_scan_complete(h);
>  
> + /*
> +  * If a scan is alreay waiting to run, no need to add another
> +  */
> + spin_lock_irqsave(>scan_lock, flags);
> + if (h->scan_waiting) {
> + spin_unlock_irqrestore(>scan_lock, flags);
> + return;
> + }
> +
> + spin_unlock_irqrestore(>scan_lock, flags);
> +
>   /* wait until any scan already in progress is finished. */
>   while (1) {
>   spin_lock_irqsave(>scan_lock, flags);

Placing the test to this place would save few lines
+   if (h->scan_waiting) {
+   spin_unlock_irqrestore(>scan_lock, flags);
+   return
but I agree with your version too.

Reviewed-by: Tomas Henzl 
tomash

[PATCH 2/3] hpsa: limit outstanding rescans

[Don Brace]

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

Reviewed-by: Scott Benesh 
Reviewed-by: Scott Teel 
Signed-off-by: Don Brace 
---
 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 1adc4ec..a36d3a6 100644
--- a/drivers/scsi/hpsa.c
+++ b/drivers/scsi/hpsa.c
@@ -5558,7 +5558,7 @@ static void hpsa_scan_complete(struct ctlr_info *h)
 
spin_lock_irqsave(>scan_lock, flags);
h->scan_finished = 1;
-   wake_up_all(>scan_wait_queue);
+   wake_up(>scan_wait_queue);
spin_unlock_irqrestore(>scan_lock, flags);
 }
 
@@ -5576,11 +5576,23 @@ static void hpsa_scan_start(struct Scsi_Host *sh)
if (unlikely(lockup_detected(h)))
return hpsa_scan_complete(h);
 
+   /*
+* If a scan is alreay waiting to run, no need to add another
+*/
+   spin_lock_irqsave(>scan_lock, flags);
+   if (h->scan_waiting) {
+   spin_unlock_irqrestore(>scan_lock, flags);
+   return;
+   }
+
+   spin_unlock_irqrestore(>scan_lock, flags);
+
/* wait until any scan already in progress is finished. */
while (1) {
spin_lock_irqsave(>scan_lock, flags);
if (h->scan_finished)
break;
+   h->scan_waiting = 1;
spin_unlock_irqrestore(>scan_lock, flags);
wait_event(h->scan_wait_queue, h->scan_finished);
/* Note: We don't need to worry about a race between this
@@ -5590,6 +5602,7 @@ 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(>scan_lock, flags);
 
if (unlikely(lockup_detected(h)))
@@ -8792,6 +8805,7 @@ static int hpsa_init_one(struct pci_dev *pdev, const 
struct pci_device_id *ent)
init_waitqueue_head(>event_sync_wait_queue);
mutex_init(>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;