linux-kernel - [PATCH 3.16 132/217] target: Fix target_release_cmd

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Message-ID: <lsq.1461711741.570387284@decadent.org.uk>
Date:	Wed, 27 Apr 2016 01:02:21 +0200
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org,
	"Nicholas Bellinger" <nab@...ux-iscsi.org>,
	"Himanshu Madhani" <himanshu.madhani@...gic.com>
Subject: [PATCH 3.16 132/217] target: Fix target_release_cmd_kref shutdown
 comp leak

3.16.35-rc1 review patch.  If anyone has any objections, please let me know.

------------------

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: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/target/target_core_transport.c | 2 --
 1 file changed, 2 deletions(-)

--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -2540,8 +2540,6 @@ void target_wait_for_sess_cmds(struct se
 
 	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));