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Commit 30002f1c authored by Ben Collins's avatar Ben Collins Committed by James Bottomley
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[SCSI] aacraid: Relax the tight timeout loop on fib commands 



The loop that waited for syncronous fib commands was causing a CPU stall
when a timeout actually occured.

1) Switch to using a more accurate timeout mechanism.
2) Do not pace the loop with udelay(). Use cpu_relax() to allow for
   scheduling to occur.

Signed-off-by: default avatarBen Collins <bcollins@ubuntu.com>
Acked-by: default avatarAchim Leubner <Achim_Leubner@pmc-sierra.com>
Signed-off-by: default avatarJames Bottomley <JBottomley@Parallels.com>
parent 361ee9c3

drivers/scsi/aacraid/commsup.c

+6 −3
Original line number Original line Diff line number Diff line
@@ -564,10 +564,10 @@ int aac_fib_send(u16 command, struct fib *fibptr, unsigned long size, 
			 * functioning because an interrupt routing or other

			 * functioning because an interrupt routing or other

			 * hardware failure has occurred.

			 * hardware failure has occurred.

			 */

			 */

			unsigned long count = 36000000L; /* 3 minutes */

			unsigned long timeout = jiffies + (180 * HZ); /* 3 minutes */

			while (down_trylock(&fibptr->event_wait)) {

			while (down_trylock(&fibptr->event_wait)) {

				int blink;

				int blink;

				if (--count == 0) {

				if (time_is_before_eq_jiffies(timeout)) {

					struct aac_queue * q = &dev->queues->queue[AdapNormCmdQueue];

					struct aac_queue * q = &dev->queues->queue[AdapNormCmdQueue];

					spin_lock_irqsave(q->lock, qflags);

					spin_lock_irqsave(q->lock, qflags);

					q->numpending--;

					q->numpending--;
@@ -588,7 +588,10 @@ int aac_fib_send(u16 command, struct fib *fibptr, unsigned long size, 
					}

					}

					return -EFAULT;

					return -EFAULT;

				}

				}

				udelay(5);

				/* We used to udelay() here but that absorbed

				 * a CPU when a timeout occured. Not very

				 * useful. */

				cpu_relax();

			}

			}

		} else if (down_interruptible(&fibptr->event_wait)) {

		} else if (down_interruptible(&fibptr->event_wait)) {

			/* Do nothing ... satisfy

			/* Do nothing ... satisfy