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 <[email protected]> Signed-off-by: Nicholas Bellinger <[email protected]>
simbayu07 · Nov 8, 2012 · 998866b · 998866b
1 parent bb7a8c8
commit 998866b
Showing 1 changed file with 2 additions and 2 deletions.
diff --git 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");