releases/4.8.5/target-re-add-missing-scf_ack_kref-assignment-in-v4.1.y.patch

   1 From 527268df31e57cf2b6d417198717c6d6afdb1e3e Mon Sep 17 00:00:00 2001
   2 From: Nicholas Bellinger <nab@linux-iscsi.org>
   3 Date: Tue, 4 Oct 2016 16:37:05 -0700
   4 Subject: target: Re-add missing SCF_ACK_KREF assignment in v4.1.y
   5
   6 From: Nicholas Bellinger <nab@linux-iscsi.org>
   7
   8 commit 527268df31e57cf2b6d417198717c6d6afdb1e3e upstream.
   9
  10 This patch fixes a regression in >= v4.1.y code where the original
  11 SCF_ACK_KREF assignment in target_get_sess_cmd() was dropped upstream
  12 in commit 054922bb, but the series for addressing TMR ABORT_TASK +
  13 LUN_RESET with fabric session reinstatement in commit febe562c20 still
  14 depends on this code in transport_cmd_finish_abort().
  15
  16 The regression manifests itself as a se_cmd->cmd_kref +1 leak, where
  17 ABORT_TASK + LUN_RESET can hang indefinately for a specific I_T session
  18 for drivers using SCF_ACK_KREF, resulting in hung kthreads.
  19
  20 This patch has been verified with v4.1.y code.
  21
  22 Reported-by: Vaibhav Tandon <vst@datera.io>
  23 Tested-by: Vaibhav Tandon <vst@datera.io>
  24 Cc: Vaibhav Tandon <vst@datera.io>
  25 Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
  26 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  27
  28 ---
  29  drivers/target/target_core_transport.c |    4 +++-
  30  1 file changed, 3 insertions(+), 1 deletion(-)
  31
  32 --- a/drivers/target/target_core_transport.c
  33 +++ b/drivers/target/target_core_transport.c
  34 @@ -2547,8 +2547,10 @@ int target_get_sess_cmd(struct se_cmd *s
  35          * fabric acknowledgement that requires two target_put_sess_cmd()
  36          * invocations before se_cmd descriptor release.
  37          */
  38 -       if (ack_kref)
  39 +       if (ack_kref) {
  40                 kref_get(&se_cmd->cmd_kref);
  41 +               se_cmd->se_cmd_flags |= SCF_ACK_KREF;
  42 +       }
  43
  44         spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
  45         if (se_sess->sess_tearing_down) {