qla2xxx: Fix sess_lock & hardware_lock lock order problem.

The main lock that needs to be held for CMD or TMR submission
to upper layer is the sess_lock. The sess_lock is used to
serialize cmd submission and session deletion. The addition
of hardware_lock being held is not necessary. This patch removes
hardware_lock dependency from CMD/TMR submission.

Use hardware_lock only for error response in this case.

Path1
       CPU0                    CPU1
       ----                    ----
  lock(&(&ha->tgt.sess_lock)->rlock);
                               lock(&(&ha->hardware_lock)->rlock);
                               lock(&(&ha->tgt.sess_lock)->rlock);
  lock(&(&ha->hardware_lock)->rlock);

Path2/deadlock
*** DEADLOCK ***
Call Trace:
dump_stack+0x85/0xc2
print_circular_bug+0x1e3/0x250
__lock_acquire+0x1425/0x1620
lock_acquire+0xbf/0x210
_raw_spin_lock_irqsave+0x53/0x70
qlt_sess_work_fn+0x21d/0x480 [qla2xxx]
process_one_work+0x1f4/0x6e0

Cc: <stable@vger.kernel.org>
Cc: Bart Van Assche <Bart.VanAssche@sandisk.com>
Reported-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
Signed-off-by: Quinn Tran <quinn.tran@cavium.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 18 insertions, 23 deletions

diff --git a/drivers/scsi/qla2xxx/qla_target.c b/drivers/scsi/qla2xxx/qla_target.c
index a78c3e9bcb57..989f931af156 100644
--- a/drivers/scsi/qla2xxx/qla_target.c
+++ b/drivers/scsi/qla2xxx/qla_target.c
@@ -5727,30 +5727,23 @@ static void qlt_abort_work(struct qla_tgt *tgt,
                 }
         }
 
-        spin_lock_irqsave(&ha->hardware_lock, flags);
-
-        if (tgt->tgt_stop)
-                goto out_term;
-
         rc = __qlt_24xx_handle_abts(vha, &prm->abts, sess);
+        ha->tgt.tgt_ops->put_sess(sess);
+        spin_unlock_irqrestore(&ha->tgt.sess_lock, flags2);
+
         if (rc != 0)
                 goto out_term;
-        spin_unlock_irqrestore(&ha->hardware_lock, flags);
-        if (sess)
-                ha->tgt.tgt_ops->put_sess(sess);
-        spin_unlock_irqrestore(&ha->tgt.sess_lock, flags2);
         return;
 
 out_term2:
-        spin_lock_irqsave(&ha->hardware_lock, flags);
+        if (sess)
+                ha->tgt.tgt_ops->put_sess(sess);
+        spin_unlock_irqrestore(&ha->tgt.sess_lock, flags2);
 
 out_term:
+        spin_lock_irqsave(&ha->hardware_lock, flags);
         qlt_24xx_send_abts_resp(vha, &prm->abts, FCP_TMF_REJECTED, false);
         spin_unlock_irqrestore(&ha->hardware_lock, flags);
-
-        if (sess)
-                ha->tgt.tgt_ops->put_sess(sess);
-        spin_unlock_irqrestore(&ha->tgt.sess_lock, flags2);
 }
 
 static void qlt_tmr_work(struct qla_tgt *tgt,
@@ -5770,7 +5763,7 @@ static void qlt_tmr_work(struct qla_tgt *tgt,
         spin_lock_irqsave(&ha->tgt.sess_lock, flags);
 
         if (tgt->tgt_stop)
-                goto out_term;
+                goto out_term2;
 
         s_id = prm->tm_iocb2.u.isp24.fcp_hdr.s_id;
         sess = ha->tgt.tgt_ops->find_sess_by_s_id(vha, s_id);
@@ -5782,11 +5775,11 @@ static void qlt_tmr_work(struct qla_tgt *tgt,
 
                 spin_lock_irqsave(&ha->tgt.sess_lock, flags);
                 if (!sess)
-                        goto out_term;
+                        goto out_term2;
         } else {
                 if (sess->deleted) {
                         sess = NULL;
-                        goto out_term;
+                        goto out_term2;
                 }
 
                 if (!kref_get_unless_zero(&sess->sess_kref)) {
@@ -5794,7 +5787,7 @@ static void qlt_tmr_work(struct qla_tgt *tgt,
                             "%s: kref_get fail %8phC\n",
                              __func__, sess->port_name);
                         sess = NULL;
-                        goto out_term;
+                        goto out_term2;
                 }
         }
 
@@ -5804,17 +5797,19 @@ static void qlt_tmr_work(struct qla_tgt *tgt,
         unpacked_lun = scsilun_to_int((struct scsi_lun *)&lun);
 
         rc = qlt_issue_task_mgmt(sess, unpacked_lun, fn, iocb, 0);
-        if (rc != 0)
-                goto out_term;
-
         ha->tgt.tgt_ops->put_sess(sess);
         spin_unlock_irqrestore(&ha->tgt.sess_lock, flags);
+
+        if (rc != 0)
+                goto out_term;
         return;
 
+out_term2:
+        if (sess)
+                ha->tgt.tgt_ops->put_sess(sess);
+        spin_unlock_irqrestore(&ha->tgt.sess_lock, flags);
 out_term:
         qlt_send_term_exchange(vha, NULL, &prm->tm_iocb2, 1, 0);
-        ha->tgt.tgt_ops->put_sess(sess);
-        spin_unlock_irqrestore(&ha->tgt.sess_lock, flags);
 }
 
 static void qlt_sess_work_fn(struct work_struct *work)