Re: [PATCH v2] drivers/md: use proper rcu accessor

[Mike Snitzer]

On Sun, Nov 23 2014 at 12:34pm -0500,
Eric Dumazet <eric.dumazet@xxxxxxxxx> wrote:

> From: Eric Dumazet <edumazet@xxxxxxxxxx>
> 
> rcu_dereference() should be used in sections protected by rcu_read_lock.
> 
> For writers, holding some kind of mutex or lock,
> rcu_dereference_protected() is the way to go, adding explicit lockdep
> bits.
> 
> In __unbind(), we are the last user of this mapped device, so can use
> the constant '1' instead of a lockdep_is_held(), not consistent with
> other uses of rcu_dereference_protected() which use md->suspend_lock
> mutex.
> 
> Reported-by: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
> Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
> Fixes: 33423974bfc1 ("dm: Use rcu_dereference() for accessing rcu pointer")
> Cc: Pranith Kumar <bobby.prani@xxxxxxxxx>
> Cc: Mike Snitzer <snitzer@xxxxxxxxxx>

Thanks, I've staged this for 3.19:
https://git.kernel.org/cgit/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=dm-for-3.19&id=a12f5d48bdfeb5fe10157ac01c3de29269f457c6
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