linux-kernel - [PATCH 3.19.y-ckt 110/170] target: Fix target_release_cmd

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Date:	Fri,  1 Apr 2016 17:53:16 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Himanshu Madhani <himanshu.madhani@...gic.com>,
	Nicholas Bellinger <nab@...ux-iscsi.org>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.19.y-ckt 110/170] target: Fix target_release_cmd_kref shutdown comp leak

3.19.8-ckt18 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Himanshu Madhani <himanshu.madhani@...gic.com>

commit 5e47f1985d7107331c3f64fb3ec83d66fd73577e upstream.

This patch fixes an active I/O shutdown bug for fabric
drivers using target_wait_for_sess_cmds(), where se_cmd
descriptor shutdown would result in hung tasks waiting
indefinitely for se_cmd->cmd_wait_comp to complete().

To address this bug, drop the incorrect list_del_init()
usage in target_wait_for_sess_cmds() and always complete()
during se_cmd target_release_cmd_kref() put, in order to
let caller invoke the final fabric release callback
into se_cmd->se_tfo->release_cmd() code.

Reported-by: Himanshu Madhani <himanshu.madhani@...gic.com>
Tested-by: Himanshu Madhani <himanshu.madhani@...gic.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@...gic.com>
Signed-off-by: Nicholas Bellinger <nab@...ux-iscsi.org>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/target/target_core_transport.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 6dedba7..16b2beb 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -2535,8 +2535,6 @@ void target_wait_for_sess_cmds(struct se_session *se_sess)
 
 	list_for_each_entry_safe(se_cmd, tmp_cmd,
 				&se_sess->sess_wait_list, se_cmd_list) {
-		list_del_init(&se_cmd->se_cmd_list);
-
 		pr_debug("Waiting for se_cmd: %p t_state: %d, fabric state:"
 			" %d\n", se_cmd, se_cmd->t_state,
 			se_cmd->se_tfo->get_cmd_state(se_cmd));
-- 
2.7.4