target: Invoke release_cmd() callback without holding a spinlock

This patch fixes the following kernel warning because it avoids that
IRQs are disabled while ft_release_cmd() is invoked (fc_seq_set_resp()
invokes spin_unlock_bh()):

WARNING: CPU: 3 PID: 117 at kernel/softirq.c:150 __local_bh_enable_ip+0xaa/0x110()
Call Trace:
 [<ffffffff814f71eb>] dump_stack+0x4f/0x7b
 [<ffffffff8105e56a>] warn_slowpath_common+0x8a/0xc0
 [<ffffffff8105e65a>] warn_slowpath_null+0x1a/0x20
 [<ffffffff81062b2a>] __local_bh_enable_ip+0xaa/0x110
 [<ffffffff814ff229>] _raw_spin_unlock_bh+0x39/0x40
 [<ffffffffa03a7f94>] fc_seq_set_resp+0xe4/0x100 [libfc]
 [<ffffffffa02e604a>] ft_free_cmd+0x4a/0x90 [tcm_fc]
 [<ffffffffa02e6972>] ft_release_cmd+0x12/0x20 [tcm_fc]
 [<ffffffffa042bd66>] target_release_cmd_kref+0x56/0x90 [target_core_mod]
 [<ffffffffa042caf0>] target_put_sess_cmd+0xc0/0x110 [target_core_mod]
 [<ffffffffa042cb81>] transport_release_cmd+0x41/0x70 [target_core_mod]
 [<ffffffffa042d975>] transport_generic_free_cmd+0x35/0x420 [target_core_mod]

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Acked-by: Joern Engel <joern@logfs.org>
Reviewed-by: Andy Grover <agrover@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

2 files changed, 12 insertions, 7 deletions

diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c
index 5b2820312310..28fb3016370f 100644
--- a/drivers/target/target_core_tmr.c
+++ b/drivers/target/target_core_tmr.c
@@ -130,6 +130,9 @@ void core_tmr_abort_task(
                 if (tmr->ref_task_tag != ref_tag)
                         continue;
 
+                if (!kref_get_unless_zero(&se_cmd->cmd_kref))
+                        continue;
+
                 printk("ABORT_TASK: Found referenced %s task_tag: %llu\n",
                         se_cmd->se_tfo->get_fabric_name(), ref_tag);
 
@@ -139,13 +142,15 @@ void core_tmr_abort_task(
                                " skipping\n", ref_tag);
                         spin_unlock(&se_cmd->t_state_lock);
                         spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
+
+                        target_put_sess_cmd(se_cmd);
+
                         goto out;
                 }
                 se_cmd->transport_state |= CMD_T_ABORTED;
                 spin_unlock(&se_cmd->t_state_lock);
 
                 list_del_init(&se_cmd->se_cmd_list);
-                kref_get(&se_cmd->cmd_kref);
                 spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
 
                 cancel_work_sync(&se_cmd->work);
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 010b8c46f1ef..4fdcee2006d1 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -2509,23 +2509,24 @@ out:
 EXPORT_SYMBOL(target_get_sess_cmd);
 
 static void target_release_cmd_kref(struct kref *kref)
-                __releases(&se_cmd->se_sess->sess_cmd_lock)
 {
         struct se_cmd *se_cmd = container_of(kref, struct se_cmd, cmd_kref);
         struct se_session *se_sess = se_cmd->se_sess;
+        unsigned long flags;
 
+        spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
         if (list_empty(&se_cmd->se_cmd_list)) {
-                spin_unlock(&se_sess->sess_cmd_lock);
+                spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
                 se_cmd->se_tfo->release_cmd(se_cmd);
                 return;
         }
         if (se_sess->sess_tearing_down && se_cmd->cmd_wait_set) {
-                spin_unlock(&se_sess->sess_cmd_lock);
+                spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
                 complete(&se_cmd->cmd_wait_comp);
                 return;
         }
         list_del(&se_cmd->se_cmd_list);
-        spin_unlock(&se_sess->sess_cmd_lock);
+        spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
 
         se_cmd->se_tfo->release_cmd(se_cmd);
 }
@@ -2541,8 +2542,7 @@ int target_put_sess_cmd(struct se_cmd *se_cmd)
                 se_cmd->se_tfo->release_cmd(se_cmd);
                 return 1;
         }
-        return kref_put_spinlock_irqsave(&se_cmd->cmd_kref, target_release_cmd_kref,
-                        &se_sess->sess_cmd_lock);
+        return kref_put(&se_cmd->cmd_kref, target_release_cmd_kref);
 }
 EXPORT_SYMBOL(target_put_sess_cmd);