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

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>
Cc: stable@vger.kernel.org # 4.1+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 6094a6b..00ec464 100644 (file)
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -2547,8 +2547,10 @@ int target_get_sess_cmd(struct se_cmd *se_cmd, bool ack_kref)
         * 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) {