On Mon, 2012-11-05 at 18:02 -0800, Roland Dreier wrote:
> From: Roland Dreier <roland@xxxxxxxxxxxxxxx>
>
> We need to disable BHs when taking sess_idr_lock because the
> iscsit_handle_time2retain_timeout() timer function takes
> se_tpg->session_lock, and iscsit_close_session() nests sess_idr_lock
> inside se_tpg->session_lock. So if the timer can run inside
> sess_idr_lock, we have a potential AB-BA deadlock.
>
> Fix this by disabling BHs when taking sess_idr_lock. This was found
> because of a lockdep warning, but it looks like a real (if highly
> theoretical) deadlock. In any case avoiding lockdep spew so that we can
> find other issues is a worthy cause.
>
> Signed-off-by: Roland Dreier <roland@xxxxxxxxxxxxxxx>
> ---
> drivers/target/iscsi/iscsi_target_login.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/target/iscsi/iscsi_target_login.c b/drivers/target/iscsi/iscsi_target_login.c
> index f8dbec0..3f34ecf 100644
> --- a/drivers/target/iscsi/iscsi_target_login.c
> +++ b/drivers/target/iscsi/iscsi_target_login.c
> @@ -254,9 +254,9 @@ static int iscsi_login_zero_tsih_s1(
> kfree(sess);
> return -ENOMEM;
> }
> - spin_lock(&sess_idr_lock);
> + spin_lock_bh(&sess_idr_lock);
> ret = idr_get_new(&sess_idr, NULL, &sess->session_index);
> - spin_unlock(&sess_idr_lock);
> + spin_unlock_bh(&sess_idr_lock);
>
> if (ret < 0) {
> pr_err("idr_get_new() for sess_idr failed\n");
Looks fine, and applied to for-next.
Thanks Roland!
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