[PATCH 3.19.y-ckt 143/210] iscsi-target: Fix potential dead-lock during node acl delete
From: Kamal Mostafa <hidden>
Date: 2016-01-29 01:43:44
Also in:
lkml
Subsystem:
scsi target subsystem, the rest · Maintainers:
"Martin K. Petersen", Linus Torvalds
3.19.8-ckt14 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: Nicholas Bellinger <redacted> commit 26a99c19f810b2593410899a5b304b21b47428a6 upstream. This patch is a iscsi-target specific bug-fix for a dead-lock that can occur during explicit struct se_node_acl->acl_group se_session deletion via configfs rmdir(2), when iscsi-target time2retain timer is still active. It changes iscsi-target to obtain se_portal_group->session_lock internally using spin_in_locked() to check for the specific se_node_acl configfs shutdown rmdir(2) case. Note this patch is intended for stable, and the subsequent v4.5-rc patch converts target_core_tpg.c to use proper se_sess->sess_kref reference counting for both se_node_acl deletion + se_node_acl->queue_depth se_session restart. Reported-by:: Sagi Grimberg [off-list ref] Cc: Christoph Hellwig <hch@lst.de> Cc: Hannes Reinecke <hare@suse.de> Cc: Andy Grover <redacted> Cc: Mike Christie <redacted> Signed-off-by: Nicholas Bellinger <redacted> Signed-off-by: Kamal Mostafa <redacted> --- drivers/target/iscsi/iscsi_target_configfs.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/drivers/target/iscsi/iscsi_target_configfs.c b/drivers/target/iscsi/iscsi_target_configfs.c
index 9059c1e..e2f1aeb 100644
--- a/drivers/target/iscsi/iscsi_target_configfs.c
+++ b/drivers/target/iscsi/iscsi_target_configfs.c@@ -1887,7 +1887,8 @@ static void lio_tpg_release_fabric_acl( } /* - * Called with spin_lock_bh(struct se_portal_group->session_lock) held.. + * Called with spin_lock_irq(struct se_portal_group->session_lock) held + * or not held. * * Also, this function calls iscsit_inc_session_usage_count() on the * struct iscsi_session in question.
@@ -1895,19 +1896,32 @@ static void lio_tpg_release_fabric_acl( static int lio_tpg_shutdown_session(struct se_session *se_sess) { struct iscsi_session *sess = se_sess->fabric_sess_ptr; + struct se_portal_group *se_tpg = se_sess->se_tpg; + bool local_lock = false; + + if (!spin_is_locked(&se_tpg->session_lock)) { + spin_lock_irq(&se_tpg->session_lock); + local_lock = true; + } spin_lock(&sess->conn_lock); if (atomic_read(&sess->session_fall_back_to_erl0) || atomic_read(&sess->session_logout) || (sess->time2retain_timer_flags & ISCSI_TF_EXPIRED)) { spin_unlock(&sess->conn_lock); + if (local_lock) + spin_unlock_irq(&sess->conn_lock); return 0; } atomic_set(&sess->session_reinstatement, 1); spin_unlock(&sess->conn_lock); iscsit_stop_time2retain_timer(sess); + spin_unlock_irq(&se_tpg->session_lock); + iscsit_stop_session(sess, 1, 1); + if (!local_lock) + spin_lock_irq(&se_tpg->session_lock); return 1; }
--
1.9.1