From: Mark Lord <liml@rtr.ca>
Date: Tue, 10 Mar 2009 20:28:51 +0000 (-0400)
Subject: sata_mv: fix MSI irq race condition
X-Git-Tag: v2.6.29~42^2~2
X-Git-Url: http://ftp.safe.ca/?p=safe%2Fjmp%2Flinux-2.6;a=commitdiff_plain;h=9d51af7bd2f1d730cb6eeeb9ff837e3441ad4e07

sata_mv: fix MSI irq race condition

Fix a (rare) race condition in mv_interrupt() when using MSI.

The value of hpriv->main_irq_mask_addr can change on on the fly,
and without this patch we could end up writing back a stale copy
to the hardware.

Signed-off-by: Mark Lord <mlord@pobox.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
---

diff --git a/drivers/ata/sata_mv.c b/drivers/ata/sata_mv.c
index 7007edd..74b1080 100644
--- a/drivers/ata/sata_mv.c
+++ b/drivers/ata/sata_mv.c
@@ -2218,12 +2218,13 @@ static irqreturn_t mv_interrupt(int irq, void *dev_instance)
 		else
 			handled = mv_host_intr(host, pending_irqs);
 	}
-	spin_unlock(&host->lock);
 
 	/* for MSI: unmask; interrupt cause bits will retrigger now */
 	if (using_msi)
 		writel(hpriv->main_irq_mask, hpriv->main_irq_mask_addr);
 
+	spin_unlock(&host->lock);
+
 	return IRQ_RETVAL(handled);
 }