From: Roland Dreier Date: Tue, 6 Nov 2012 02:02:40 +0000 (-0800) Subject: iscsi-target: Fix potential deadlock on lock taken in timer X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=998866b0740f128fd2c107c167c8385406dadae0;p=linux-beck.git 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 Signed-off-by: Nicholas Bellinger --- diff --git a/drivers/target/iscsi/iscsi_target_login.c b/drivers/target/iscsi/iscsi_target_login.c index f8dbec05d5e5..3f34ecf87b1e 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");