Patch "target: Re-add missing SCF_ACK_KREF assignment in v4.1.y" has been added to the 4.4-stable tree

Patch "target: Re-add missing SCF_ACK_KREF assignment in v4.1.y" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    target: Re-add missing SCF_ACK_KREF assignment in v4.1.y

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     target-re-add-missing-scf_ack_kref-assignment-in-v4.1.y.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 527268df31e57cf2b6d417198717c6d6afdb1e3e Mon Sep 17 00:00:00 2001
From: Nicholas Bellinger <nab@linux-iscsi.org>
Date: Tue, 4 Oct 2016 16:37:05 -0700
Subject: target: Re-add missing SCF_ACK_KREF assignment in v4.1.y

From: Nicholas Bellinger <nab@linux-iscsi.org>

commit 527268df31e57cf2b6d417198717c6d6afdb1e3e upstream.

This patch fixes a regression in >= v4.1.y code where the original
SCF_ACK_KREF assignment in target_get_sess_cmd() was dropped upstream
in commit 054922bb, but the series for addressing TMR ABORT_TASK +
LUN_RESET with fabric session reinstatement in commit febe562c20 still
depends on this code in transport_cmd_finish_abort().

The regression manifests itself as a se_cmd->cmd_kref +1 leak, where
ABORT_TASK + LUN_RESET can hang indefinately for a specific I_T session
for drivers using SCF_ACK_KREF, resulting in hung kthreads.

This patch has been verified with v4.1.y code.

Reported-by: Vaibhav Tandon <vst@datera.io>
Tested-by: Vaibhav Tandon <vst@datera.io>
Cc: Vaibhav Tandon <vst@datera.io>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/target/target_core_transport.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -2509,8 +2509,10 @@ int target_get_sess_cmd(struct se_cmd *s
 	 * fabric acknowledgement that requires two target_put_sess_cmd()
 	 * invocations before se_cmd descriptor release.
 	 */
-	if (ack_kref)
+	if (ack_kref) {
 		kref_get(&se_cmd->cmd_kref);
+		se_cmd->se_cmd_flags |= SCF_ACK_KREF;
+	}
 
 	spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
 	if (se_sess->sess_tearing_down) {


Patches currently in stable-queue which might be from nab@linux-iscsi.org are

queue-4.4/target-re-add-missing-scf_ack_kref-assignment-in-v4.1.y.patch
queue-4.4/target-don-t-override-extended_copy-xcopy_pt_cmd-scsi-status-code.patch
queue-4.4/target-make-extended_copy-0xe4-failure-return-copy-target-device-not-reachable.patch