From bc78c57388e7f447f58e30d60b1505ddaaaf3a7d Mon Sep 17 00:00:00 2001 From: Denis Efremov Date: Thu, 11 Oct 2012 13:08:02 +1100 Subject: [PATCH] md/linear: rcu_dereference outside read-lock section According to the comment in linear_stop function rcu_dereference in linear_start and linear_stop functions occurs under reconfig_mutex. The patch represents this agreement in code and prevents lockdep complaint. Found by Linux Driver Verification project (linuxtesting.org) Signed-off-by: Denis Efremov Signed-off-by: NeilBrown --- drivers/md/linear.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/md/linear.c b/drivers/md/linear.c index fa211d80fc0a..92c64d162a92 100644 --- a/drivers/md/linear.c +++ b/drivers/md/linear.c @@ -244,7 +244,9 @@ static int linear_add(struct mddev *mddev, struct md_rdev *rdev) if (!newconf) return -ENOMEM; - oldconf = rcu_dereference(mddev->private); + oldconf = rcu_dereference_protected(mddev->private, + lockdep_is_held( + &mddev->reconfig_mutex)); mddev->raid_disks++; rcu_assign_pointer(mddev->private, newconf); md_set_array_sectors(mddev, linear_size(mddev, 0, 0)); @@ -256,7 +258,10 @@ static int linear_add(struct mddev *mddev, struct md_rdev *rdev) static int linear_stop (struct mddev *mddev) { - struct linear_conf *conf = mddev->private; + struct linear_conf *conf = + rcu_dereference_protected(mddev->private, + lockdep_is_held( + &mddev->reconfig_mutex)); /* * We do not require rcu protection here since -- 2.20.1