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hpsa: count passthru cmds with atomics, not a spin locked int

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Performance enhancement. Remove spin_locks from the driver.

Reviewed-by: Scott Teel <scott.teel@pmcs.com>
Signed-off-by: Don Brace <don.brace@pmcs.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Don Brace 2015-01-23 16:43:46 -06:00 committed by James Bottomley
parent 33811026a0
commit 34f0c6277c
2 changed files with 6 additions and 36 deletions
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39
drivers/scsi/hpsa.c
View File

@ -5105,35 +5105,6 @@ static void check_ioctl_unit_attention(struct ctlr_info *h,
(void) check_for_unit_attention(h, c);
}
static int increment_passthru_count(struct ctlr_info *h)
{
unsigned long flags;
spin_lock_irqsave(&h->passthru_count_lock, flags);
if (h->passthru_count >= HPSA_MAX_CONCURRENT_PASSTHRUS) {
spin_unlock_irqrestore(&h->passthru_count_lock, flags);
return -1;
}
h->passthru_count++;
spin_unlock_irqrestore(&h->passthru_count_lock, flags);
return 0;
}
static void decrement_passthru_count(struct ctlr_info *h)
{
unsigned long flags;
spin_lock_irqsave(&h->passthru_count_lock, flags);
if (h->passthru_count <= 0) {
spin_unlock_irqrestore(&h->passthru_count_lock, flags);
/* not expecting to get here. */
dev_warn(&h->pdev->dev, "Bug detected, passthru_count seems to be incorrect.\n");
return;
}
h->passthru_count--;
spin_unlock_irqrestore(&h->passthru_count_lock, flags);
}
/*
* ioctl
*/
@ -5156,16 +5127,16 @@ static int hpsa_ioctl(struct scsi_device *dev, int cmd, void __user *arg)
case CCISS_GETDRIVVER:
return hpsa_getdrivver_ioctl(h, argp);
case CCISS_PASSTHRU:
if (increment_passthru_count(h))
if (atomic_dec_if_positive(&h->passthru_cmds_avail) < 0)
return -EAGAIN;
rc = hpsa_passthru_ioctl(h, argp);
decrement_passthru_count(h);
atomic_inc(&h->passthru_cmds_avail);
return rc;
case CCISS_BIG_PASSTHRU:
if (increment_passthru_count(h))
if (atomic_dec_if_positive(&h->passthru_cmds_avail) < 0)
return -EAGAIN;
rc = hpsa_big_passthru_ioctl(h, argp);
decrement_passthru_count(h);
atomic_inc(&h->passthru_cmds_avail);
return rc;
default:
return -ENOTTY;
@ -6852,7 +6823,7 @@ reinit_after_soft_reset:
spin_lock_init(&h->lock);
spin_lock_init(&h->offline_device_lock);
spin_lock_init(&h->scan_lock);
spin_lock_init(&h->passthru_count_lock);
atomic_set(&h->passthru_cmds_avail, HPSA_MAX_CONCURRENT_PASSTHRUS);
h->resubmit_wq = alloc_workqueue("hpsa", WQ_MEM_RECLAIM, 0);
if (!h->resubmit_wq) {

3
drivers/scsi/hpsa.h
View File

@ -183,8 +183,7 @@ struct ctlr_info {
/* cap concurrent passthrus at some reasonable maximum */
#define HPSA_MAX_CONCURRENT_PASSTHRUS (10)
spinlock_t passthru_count_lock; /* protects passthru_count */
int passthru_count;
atomic_t passthru_cmds_avail;
/*
* Performant mode completion buffers