target: Fix LUN_RESET active TMR descriptor handling

This patch fixes a NULL pointer se_cmd->cmd_kref < 0
refcount bug during TMR LUN_RESET with active TMRs,
triggered during se_cmd + se_tmr_req descriptor
shutdown + release via core_tmr_drain_tmr_list().

To address this bug, go ahead and obtain a local
kref_get_unless_zero(&se_cmd->cmd_kref) for active I/O
to set CMD_T_ABORTED, and transport_wait_for_tasks()
followed by the final target_put_sess_cmd() to drop
the local ->cmd_kref.

Also add two new checks within target_tmr_work() to
avoid CMD_T_ABORTED -> TFO->queue_tm_rsp() callbacks
ahead of invoking the backend -> fabric put in
transport_cmd_check_stop_to_fabric().

For good measure, also change core_tmr_release_req()
to use list_del_init() ahead of se_tmr_req memory
free.

Reviewed-by: Quinn Tran <quinn.tran@qlogic.com>
Cc: Himanshu Madhani <himanshu.madhani@qlogic.com>
Cc: Sagi Grimberg <sagig@mellanox.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Andy Grover <agrover@redhat.com>
Cc: Mike Christie <mchristi@redhat.com>
Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c
index fb3decc28589114c085a752d56102dddcb75360c..072af07bd2ff423883b8634473767c87691eb041 100644 (file)
--- a/drivers/target/target_core_tmr.c
+++ b/drivers/target/target_core_tmr.c
@@ -68,7 +68,7 @@ void core_tmr_release_req(struct se_tmr_req *tmr)
 
        if (dev) {
                spin_lock_irqsave(&dev->se_tmr_lock, flags);
-               list_del(&tmr->tmr_list);
+               list_del_init(&tmr->tmr_list);
                spin_unlock_irqrestore(&dev->se_tmr_lock, flags);
        }
 
@@ -194,9 +194,11 @@ static void core_tmr_drain_tmr_list(
        struct list_head *preempt_and_abort_list)
 {
        LIST_HEAD(drain_tmr_list);
+       struct se_session *sess;
        struct se_tmr_req *tmr_p, *tmr_pp;
        struct se_cmd *cmd;
        unsigned long flags;
+       bool rc;
        /*
         * Release all pending and outgoing TMRs aside from the received
         * LUN_RESET tmr..
@@ -222,17 +224,31 @@ static void core_tmr_drain_tmr_list(
                if (target_check_cdb_and_preempt(preempt_and_abort_list, cmd))
                        continue;
 
+               sess = cmd->se_sess;
+               if (WARN_ON_ONCE(!sess))
+                       continue;
+
+               spin_lock(&sess->sess_cmd_lock);
                spin_lock(&cmd->t_state_lock);
                if (!(cmd->transport_state & CMD_T_ACTIVE)) {
                        spin_unlock(&cmd->t_state_lock);
+                       spin_unlock(&sess->sess_cmd_lock);
                        continue;
                }
                if (cmd->t_state == TRANSPORT_ISTATE_PROCESSING) {
                        spin_unlock(&cmd->t_state_lock);
+                       spin_unlock(&sess->sess_cmd_lock);
                        continue;
                }
+               cmd->transport_state |= CMD_T_ABORTED;
                spin_unlock(&cmd->t_state_lock);
 
+               rc = kref_get_unless_zero(&cmd->cmd_kref);
+               spin_unlock(&sess->sess_cmd_lock);
+               if (!rc) {
+                       printk("LUN_RESET TMR: non-zero kref_get_unless_zero\n");
+                       continue;
+               }
                list_move_tail(&tmr_p->tmr_list, &drain_tmr_list);
        }
        spin_unlock_irqrestore(&dev->se_tmr_lock, flags);
@@ -246,7 +262,11 @@ static void core_tmr_drain_tmr_list(
                        (preempt_and_abort_list) ? "Preempt" : "", tmr_p,
                        tmr_p->function, tmr_p->response, cmd->t_state);
 
+               cancel_work_sync(&cmd->work);
+               transport_wait_for_tasks(cmd);
+
                transport_cmd_finish_abort(cmd, 1);
+               target_put_sess_cmd(cmd);
        }
 }
 

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index af52f8bd8954fad13bfe3673ff366282b218aee4..94e372af9e28bd8913e27e2617364000cbe5b7ac 100644 (file)
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -2900,8 +2900,17 @@ static void target_tmr_work(struct work_struct *work)
        struct se_cmd *cmd = container_of(work, struct se_cmd, work);
        struct se_device *dev = cmd->se_dev;
        struct se_tmr_req *tmr = cmd->se_tmr_req;
+       unsigned long flags;
        int ret;
 
+       spin_lock_irqsave(&cmd->t_state_lock, flags);
+       if (cmd->transport_state & CMD_T_ABORTED) {
+               tmr->response = TMR_FUNCTION_REJECTED;
+               spin_unlock_irqrestore(&cmd->t_state_lock, flags);
+               goto check_stop;
+       }
+       spin_unlock_irqrestore(&cmd->t_state_lock, flags);
+
        switch (tmr->function) {
        case TMR_ABORT_TASK:
                core_tmr_abort_task(dev, tmr, cmd->se_sess);
@@ -2934,9 +2943,17 @@ static void target_tmr_work(struct work_struct *work)
                break;
        }
 
+       spin_lock_irqsave(&cmd->t_state_lock, flags);
+       if (cmd->transport_state & CMD_T_ABORTED) {
+               spin_unlock_irqrestore(&cmd->t_state_lock, flags);
+               goto check_stop;
+       }
        cmd->t_state = TRANSPORT_ISTATE_PROCESSING;
+       spin_unlock_irqrestore(&cmd->t_state_lock, flags);
+
        cmd->se_tfo->queue_tm_rsp(cmd);
 
+check_stop:
        transport_cmd_check_stop_to_fabric(cmd);
 }