[3.8.y.z extended stable] Patch "iscsi-target: Fix incorrect np->np_thread NULL assignment" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    iscsi-target: Fix incorrect np->np_thread NULL assignment

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.27.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 595c85aceffc8439e0ce9dbbfc29fd37eb3e99c3 Mon Sep 17 00:00:00 2001
From: Nicholas Bellinger <nab at linux-iscsi.org>
Date: Wed, 11 Dec 2013 15:45:32 -0800
Subject: iscsi-target: Fix incorrect np->np_thread NULL assignment

commit db6077fd0b7dd41dc6ff18329cec979379071f87 upstream.

When shutting down a target there is a race condition between
iscsit_del_np() and __iscsi_target_login_thread().
The latter sets the thread pointer to NULL, and the former
tries to issue kthread_stop() on that pointer without any
synchronization.

This patch moves the np->np_thread NULL assignment into
iscsit_del_np(), after kthread_stop() has completed. It also
removes the signal_pending() + np_state check, and only
exits when kthread_should_stop() is true.

Reported-by: Hannes Reinecke <hare at suse.de>
Signed-off-by: Nicholas Bellinger <nab at linux-iscsi.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/target/iscsi/iscsi_target.c       | 1 +
 drivers/target/iscsi/iscsi_target_login.c | 5 -----
 2 files changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index a6326f1..ba56bfe 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -460,6 +460,7 @@ int iscsit_del_np(struct iscsi_np *np)
 		 */
 		send_sig(SIGINT, np->np_thread, 1);
 		kthread_stop(np->np_thread);
+		np->np_thread = NULL;
 	}
 	iscsit_del_np_comm(np);

diff --git a/drivers/target/iscsi/iscsi_target_login.c b/drivers/target/iscsi/iscsi_target_login.c
index fdb632f..6b82c62 100644
--- a/drivers/target/iscsi/iscsi_target_login.c
+++ b/drivers/target/iscsi/iscsi_target_login.c
@@ -1167,11 +1167,6 @@ old_sess_out:

 out:
 	stop = kthread_should_stop();
-	if (!stop && signal_pending(current)) {
-		spin_lock_bh(&np->np_thread_lock);
-		stop = (np->np_thread_state == ISCSI_NP_THREAD_SHUTDOWN);
-		spin_unlock_bh(&np->np_thread_lock);
-	}
 	/* Wait for another socket.. */
 	if (!stop)
 		return 1;
--
1.9.1