Commit 34f0c627 authored by Don Brace's avatar Don Brace Committed by James Bottomley
Browse files

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



Performance enhancement. Remove spin_locks from the driver.

Reviewed-by: default avatarScott Teel <scott.teel@pmcs.com>
Signed-off-by: default avatarDon Brace <don.brace@pmcs.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent 33811026

drivers/scsi/hpsa.c

+5 −34
Original line number Diff line number Diff line
@@ -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 @@ static int hpsa_init_one(struct pci_dev *pdev, const struct pci_device_id *ent) 
	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) {

drivers/scsi/hpsa.h

+1 −2
Original line number Diff line number Diff line
@@ -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