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SubjectRe: [PATCH] tcm_fc: rcu_deref outside rcu lock/unlock section
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On Sat, 2012-08-18 at 16:10 +0400, Denis Efremov wrote:
> Use rcu_dereference_protected in order to prevent lockdep
> complaint. Sequel of the patch 863555be
>
> Found by Linux Driver Verification project (linuxtesting.org).
>
> Signed-off-by: Denis Efremov <yefremov.denis@gmail.com>
> ---
> drivers/target/tcm_fc/tfc_sess.c | 4 +++-
> 1 files changed, 3 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/target/tcm_fc/tfc_sess.c b/drivers/target/tcm_fc/tfc_sess.c
> index 87901fa..3c9e5b5 100644
> --- a/drivers/target/tcm_fc/tfc_sess.c
> +++ b/drivers/target/tcm_fc/tfc_sess.c
> @@ -456,7 +456,9 @@ static void ft_prlo(struct fc_rport_priv *rdata)
> struct ft_tport *tport;
>
> mutex_lock(&ft_lport_lock);
> - tport = rcu_dereference(rdata->local_port->prov[FC_TYPE_FCP]);
> + tport = rcu_dereference_protected(rdata->local_port->prov[FC_TYPE_FCP],
> + lockdep_is_held(&ft_lport_lock));
> +
> if (!tport) {
> mutex_unlock(&ft_lport_lock);
> return;

This looks OK to silence lockdep. CC'ing MDR + Kiran for good measure
here, and will move from target-pending queue -> master with their ACK.

Thanks Dennis!

--nab



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