From: NeilBrown <neilb@suse.de>
Date: Thu, 11 Oct 2012 02:50:12 +0000 (+1100)
Subject: md/raid5: add some missing locking in handle_failed_stripe.
X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=143c4d0573caebe0ae017097614349697e2280eb;p=sagit-ice-cold%2Fkernel_xiaomi_msm8998.git

md/raid5: add some missing locking in handle_failed_stripe.

We really should hold the stripe_lock while accessing
'toread' else we could race with add_stripe_bio and corrupt
a list.

Reported-by: "Jianpeng Ma" <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
---

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 758b77296404..36c0a158730b 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2552,8 +2552,10 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
 		if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
 		    (!test_bit(R5_Insync, &sh->dev[i].flags) ||
 		      test_bit(R5_ReadError, &sh->dev[i].flags))) {
+			spin_lock_irq(&sh->stripe_lock);
 			bi = sh->dev[i].toread;
 			sh->dev[i].toread = NULL;
+			spin_unlock_irq(&sh->stripe_lock);
 			if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
 				wake_up(&conf->wait_for_overlap);
 			if (bi) s->to_read--;