[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: NBen Collins <bcollins@ubuntu.com>
Acked-by: NAchim Leubner <Achim_Leubner@pmc-sierra.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

drivers/scsi/aacraid/commsup.c

@@ -564,10 +564,10 @@ int aac_fib_send(u16 command, struct fib *fibptr, unsigned long size,
 			 * functioning because an interrupt routing or other
 			 * hardware failure has occurred.
 			 */
-			unsigned long count = 36000000L; /* 3 minutes */
+			unsigned long timeout = jiffies + (180 * HZ); /* 3 minutes */
 			while (down_trylock(&fibptr->event_wait)) {
 				int blink;
-				if (--count == 0) {
+				if (time_is_before_eq_jiffies(timeout)) {
 					struct aac_queue * q = &dev->queues->queue[AdapNormCmdQueue];
 					spin_lock_irqsave(q->lock, qflags);
 					q->numpending--;
@@ -588,7 +588,10 @@ int aac_fib_send(u16 command, struct fib *fibptr, unsigned long size,
 					}
 					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)) {
 			/* Do nothing ... satisfy