[PATCH] ppc64: SMU driver: locking mistake

[Benjamin Herrenschmidt]

The SMU driver has a small mistake in the locking of the interrupt code,
if polled access and interrupt access race, interrupt may take a lock
and return without releasing it. This fixes it. With that patch, the
driver is rock solid with my experimental thermal control (which bangs
it pretty hard) racing with real time clock and cpufreq handling.

Signed-off-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>

Index: linux-work/drivers/macintosh/smu.c
===================================================================
--- linux-work.orig/drivers/macintosh/smu.c	2005-09-29 16:51:57.000000000 +1000
+++ linux-work/drivers/macintosh/smu.c	2005-09-29 16:52:37.000000000 +1000
@@ -155,8 +155,10 @@
 	spin_lock_irqsave(&smu->lock, flags);
 
 	gpio = pmac_do_feature_call(PMAC_FTR_READ_GPIO, NULL, smu->doorbell);
-	if ((gpio & 7) != 7)
+	if ((gpio & 7) != 7) {
+		spin_unlock_irqrestore(&smu->lock, flags);
 		return IRQ_HANDLED;
+	}
 
 	cmd = smu->cmd_cur;
 	smu->cmd_cur = NULL;