iscsi-target: Fix potential deadlock on lock taken in timer
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@purestorage.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
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 @@
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");