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    SubjectRe: [PATCH] md/linear: rcu_dereference outside read-lock section
    On Tue, 14 Aug 2012 01:08:12 +0400 Denis Efremov <yefremov.denis@gmail.com>
    wrote:

    > 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 <yefremov.denis@gmail.com>
    > ---
    > drivers/md/linear.c | 7 +++++--
    > 1 files changed, 5 insertions(+), 2 deletions(-)
    >
    > diff --git a/drivers/md/linear.c b/drivers/md/linear.c
    > index fa211d8..093f3e4 100644
    > --- a/drivers/md/linear.c
    > +++ b/drivers/md/linear.c
    > @@ -244,7 +244,8 @@ 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 +257,9 @@ 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


    Applied, thanks.

    NeilBrown
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