target: Re-org of core_tmr_lun_reset

This patch is a re-orginzation of core_tmr_lun_reset() logic to properly
scan the active tmr_list, dev->state_task_list and qobj->qobj_list w/ the
relivent locks held, and performing a list_move_tail onto seperate local
scope lists before performing the full drain.

This involves breaking out the code into three seperate list specific
functions: core_tmr_drain_tmr_list(), core_tmr_drain_task_list() and
core_tmr_drain_cmd_list().

(nab: Include target: Remove non-active tasks from execute list during
      LUN_RESET patch to address original breakage)

Reported-by: Roland Dreier <roland@purestorage.com>
Cc: Roland Dreier <roland@purestorage.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: stable@kernel.org
Signed-off-by: Nicholas Bellinger <nab@risingtidesystems.com>

1 files changed, 125 insertions, 72 deletions

diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c
index 98b12a8923f0..ed0b1ff99110 100644
--- a/drivers/target/target_core_tmr.c
+++ b/drivers/target/target_core_tmr.c
@@ -66,15 +66,16 @@ void core_tmr_release_req(
         struct se_tmr_req *tmr)
 {
         struct se_device *dev = tmr->tmr_dev;
+        unsigned long flags;
 
         if (!dev) {
                 kmem_cache_free(se_tmr_req_cache, tmr);
                 return;
         }
 
-        spin_lock_irq(&dev->se_tmr_lock);
+        spin_lock_irqsave(&dev->se_tmr_lock, flags);
         list_del(&tmr->tmr_list);
-        spin_unlock_irq(&dev->se_tmr_lock);
+        spin_unlock_irqrestore(&dev->se_tmr_lock, flags);
 
         kmem_cache_free(se_tmr_req_cache, tmr);
 }
@@ -99,54 +100,20 @@ static void core_tmr_handle_tas_abort(
         transport_cmd_finish_abort(cmd, 0);
 }
 
-int core_tmr_lun_reset(
+static void core_tmr_drain_tmr_list(
         struct se_device *dev,
         struct se_tmr_req *tmr,
-        struct list_head *preempt_and_abort_list,
-        struct se_cmd *prout_cmd)
+        struct list_head *preempt_and_abort_list)
 {
-        struct se_cmd *cmd, *tcmd;
-        struct se_node_acl *tmr_nacl = NULL;
-        struct se_portal_group *tmr_tpg = NULL;
-        struct se_queue_obj *qobj = &dev->dev_queue_obj;
+        LIST_HEAD(drain_tmr_list);
         struct se_tmr_req *tmr_p, *tmr_pp;
-        struct se_task *task, *task_tmp;
+        struct se_cmd *cmd;
         unsigned long flags;
-        int fe_count, tas;
-        /*
-         * TASK_ABORTED status bit, this is configurable via ConfigFS
-         * struct se_device attributes.  spc4r17 section 7.4.6 Control mode page
-         *
-         * A task aborted status (TAS) bit set to zero specifies that aborted
-         * tasks shall be terminated by the device server without any response
-         * to the application client. A TAS bit set to one specifies that tasks
-         * aborted by the actions of an I_T nexus other than the I_T nexus on
-         * which the command was received shall be completed with TASK ABORTED
-         * status (see SAM-4).
-         */
-        tas = dev->se_sub_dev->se_dev_attrib.emulate_tas;
-        /*
-         * Determine if this se_tmr is coming from a $FABRIC_MOD
-         * or struct se_device passthrough..
-         */
-        if (tmr && tmr->task_cmd && tmr->task_cmd->se_sess) {
-                tmr_nacl = tmr->task_cmd->se_sess->se_node_acl;
-                tmr_tpg = tmr->task_cmd->se_sess->se_tpg;
-                if (tmr_nacl && tmr_tpg) {
-                        pr_debug("LUN_RESET: TMR caller fabric: %s"
-                                " initiator port %s\n",
-                                tmr_tpg->se_tpg_tfo->get_fabric_name(),
-                                tmr_nacl->initiatorname);
-                }
-        }
-        pr_debug("LUN_RESET: %s starting for [%s], tas: %d\n",
-                (preempt_and_abort_list) ? "Preempt" : "TMR",
-                dev->transport->name, tas);
         /*
          * Release all pending and outgoing TMRs aside from the received
          * LUN_RESET tmr..
          */
-        spin_lock_irq(&dev->se_tmr_lock);
+        spin_lock_irqsave(&dev->se_tmr_lock, flags);
         list_for_each_entry_safe(tmr_p, tmr_pp, &dev->dev_tmr_list, tmr_list) {
                 /*
                  * Allow the received TMR to return with FUNCTION_COMPLETE.
@@ -168,29 +135,48 @@ int core_tmr_lun_reset(
                     (core_scsi3_check_cdb_abort_and_preempt(
                                         preempt_and_abort_list, cmd) != 0))
                         continue;
-                spin_unlock_irq(&dev->se_tmr_lock);
 
-                spin_lock_irqsave(&cmd->t_state_lock, flags);
+                spin_lock(&cmd->t_state_lock);
                 if (!atomic_read(&cmd->t_transport_active)) {
-                        spin_unlock_irqrestore(&cmd->t_state_lock, flags);
-                        spin_lock_irq(&dev->se_tmr_lock);
+                        spin_unlock(&cmd->t_state_lock);
                         continue;
                 }
                 if (cmd->t_state == TRANSPORT_ISTATE_PROCESSING) {
-                        spin_unlock_irqrestore(&cmd->t_state_lock, flags);
-                        spin_lock_irq(&dev->se_tmr_lock);
+                        spin_unlock(&cmd->t_state_lock);
                         continue;
                 }
+                spin_unlock(&cmd->t_state_lock);
+
+                list_move_tail(&tmr->tmr_list, &drain_tmr_list);
+        }
+        spin_unlock_irqrestore(&dev->se_tmr_lock, flags);
+
+        while (!list_empty(&drain_tmr_list)) {
+                tmr = list_entry(drain_tmr_list.next, struct se_tmr_req, tmr_list);
+                list_del(&tmr->tmr_list);
+                cmd = tmr_p->task_cmd;
+
                 pr_debug("LUN_RESET: %s releasing TMR %p Function: 0x%02x,"
                         " Response: 0x%02x, t_state: %d\n",
-                        (preempt_and_abort_list) ? "Preempt" : "", tmr_p,
-                        tmr_p->function, tmr_p->response, cmd->t_state);
-                spin_unlock_irqrestore(&cmd->t_state_lock, flags);
+                        (preempt_and_abort_list) ? "Preempt" : "", tmr,
+                        tmr->function, tmr->response, cmd->t_state);
 
                 transport_cmd_finish_abort_tmr(cmd);
-                spin_lock_irq(&dev->se_tmr_lock);
         }
-        spin_unlock_irq(&dev->se_tmr_lock);
+}
+
+static void core_tmr_drain_task_list(
+        struct se_device *dev,
+        struct se_cmd *prout_cmd,
+        struct se_node_acl *tmr_nacl,
+        int tas,
+        struct list_head *preempt_and_abort_list)
+{
+        LIST_HEAD(drain_task_list);
+        struct se_cmd *cmd;
+        struct se_task *task, *task_tmp;
+        unsigned long flags;
+        int fe_count;
         /*
          * Complete outstanding struct se_task CDBs with TASK_ABORTED SAM status.
          * This is following sam4r17, section 5.6 Aborting commands, Table 38
@@ -235,9 +221,23 @@ int core_tmr_lun_reset(
                 if (prout_cmd == cmd)
                         continue;
 
-                list_del(&task->t_state_list);
+                list_move_tail(&task->t_state_list, &drain_task_list);
                 atomic_set(&task->task_state_active, 0);
-                spin_unlock_irqrestore(&dev->execute_task_lock, flags);
+                /*
+                 * Remove from task execute list before processing drain_task_list
+                 */
+                if (atomic_read(&task->task_execute_queue) != 0) {
+                        list_del(&task->t_execute_list);
+                        atomic_set(&task->task_execute_queue, 0);
+                        atomic_dec(&dev->execute_tasks);
+                }
+        }
+        spin_unlock_irqrestore(&dev->execute_task_lock, flags);
+
+        while (!list_empty(&drain_task_list)) {
+                task = list_entry(drain_task_list.next, struct se_task, t_state_list);
+                list_del(&task->t_state_list);
+                cmd = task->task_se_cmd;
 
                 spin_lock_irqsave(&cmd->t_state_lock, flags);
                 pr_debug("LUN_RESET: %s cmd: %p task: %p"
@@ -274,20 +274,14 @@ int core_tmr_lun_reset(
 
                         atomic_set(&task->task_active, 0);
                         atomic_set(&task->task_stop, 0);
-                } else {
-                        if (atomic_read(&task->task_execute_queue) != 0)
-                                transport_remove_task_from_execute_queue(task, dev);
                 }
                 __transport_stop_task_timer(task, &flags);
 
                 if (!atomic_dec_and_test(&cmd->t_task_cdbs_ex_left)) {
-                        spin_unlock_irqrestore(
-                                        &cmd->t_state_lock, flags);
+                        spin_unlock_irqrestore(&cmd->t_state_lock, flags);
                         pr_debug("LUN_RESET: Skipping task: %p, dev: %p for"
                                 " t_task_cdbs_ex_left: %d\n", task, dev,
                                 atomic_read(&cmd->t_task_cdbs_ex_left));
-
-                        spin_lock_irqsave(&dev->execute_task_lock, flags);
                         continue;
                 }
                 fe_count = atomic_read(&cmd->t_fe_count);
@@ -297,22 +291,31 @@ int core_tmr_lun_reset(
                                 " task: %p, t_fe_count: %d dev: %p\n", task,
                                 fe_count, dev);
                         atomic_set(&cmd->t_transport_aborted, 1);
-                        spin_unlock_irqrestore(&cmd->t_state_lock,
-                                                flags);
-                        core_tmr_handle_tas_abort(tmr_nacl, cmd, tas, fe_count);
+                        spin_unlock_irqrestore(&cmd->t_state_lock, flags);
 
-                        spin_lock_irqsave(&dev->execute_task_lock, flags);
+                        core_tmr_handle_tas_abort(tmr_nacl, cmd, tas, fe_count);
                         continue;
                 }
                 pr_debug("LUN_RESET: Got t_transport_active = 0 for task: %p,"
                         " t_fe_count: %d dev: %p\n", task, fe_count, dev);
                 atomic_set(&cmd->t_transport_aborted, 1);
                 spin_unlock_irqrestore(&cmd->t_state_lock, flags);
-                core_tmr_handle_tas_abort(tmr_nacl, cmd, tas, fe_count);
 
-                spin_lock_irqsave(&dev->execute_task_lock, flags);
+                core_tmr_handle_tas_abort(tmr_nacl, cmd, tas, fe_count);
         }
-        spin_unlock_irqrestore(&dev->execute_task_lock, flags);
+}
+
+static void core_tmr_drain_cmd_list(
+        struct se_device *dev,
+        struct se_cmd *prout_cmd,
+        struct se_node_acl *tmr_nacl,
+        int tas,
+        struct list_head *preempt_and_abort_list)
+{
+        LIST_HEAD(drain_cmd_list);
+        struct se_queue_obj *qobj = &dev->dev_queue_obj;
+        struct se_cmd *cmd, *tcmd;
+        unsigned long flags;
         /*
          * Release all commands remaining in the struct se_device cmd queue.
          *
@@ -337,10 +340,15 @@ int core_tmr_lun_reset(
                 if (prout_cmd == cmd)
                         continue;
 
-                atomic_dec(&cmd->t_transport_queue_active);
+                atomic_set(&cmd->t_transport_queue_active, 0);
                 atomic_dec(&qobj->queue_cnt);
+                list_move_tail(&cmd->se_queue_node, &drain_cmd_list);
+        }
+        spin_unlock_irqrestore(&qobj->cmd_queue_lock, flags);
+
+        while (!list_empty(&drain_cmd_list)) {
+                cmd = list_entry(drain_cmd_list.next, struct se_cmd, se_queue_node);
                 list_del_init(&cmd->se_queue_node);
-                spin_unlock_irqrestore(&qobj->cmd_queue_lock, flags);
 
                 pr_debug("LUN_RESET: %s from Device Queue: cmd: %p t_state:"
                         " %d t_fe_count: %d\n", (preempt_and_abort_list) ?
@@ -353,9 +361,53 @@ int core_tmr_lun_reset(
 
                 core_tmr_handle_tas_abort(tmr_nacl, cmd, tas,
                                 atomic_read(&cmd->t_fe_count));
-                spin_lock_irqsave(&qobj->cmd_queue_lock, flags);
         }
-        spin_unlock_irqrestore(&qobj->cmd_queue_lock, flags);
+}
+
+int core_tmr_lun_reset(
+        struct se_device *dev,
+        struct se_tmr_req *tmr,
+        struct list_head *preempt_and_abort_list,
+        struct se_cmd *prout_cmd)
+{
+        struct se_node_acl *tmr_nacl = NULL;
+        struct se_portal_group *tmr_tpg = NULL;
+        int tas;
+        /*
+         * TASK_ABORTED status bit, this is configurable via ConfigFS
+         * struct se_device attributes.  spc4r17 section 7.4.6 Control mode page
+         *
+         * A task aborted status (TAS) bit set to zero specifies that aborted
+         * tasks shall be terminated by the device server without any response
+         * to the application client. A TAS bit set to one specifies that tasks
+         * aborted by the actions of an I_T nexus other than the I_T nexus on
+         * which the command was received shall be completed with TASK ABORTED
+         * status (see SAM-4).
+         */
+        tas = dev->se_sub_dev->se_dev_attrib.emulate_tas;
+        /*
+         * Determine if this se_tmr is coming from a $FABRIC_MOD
+         * or struct se_device passthrough..
+         */
+        if (tmr && tmr->task_cmd && tmr->task_cmd->se_sess) {
+                tmr_nacl = tmr->task_cmd->se_sess->se_node_acl;
+                tmr_tpg = tmr->task_cmd->se_sess->se_tpg;
+                if (tmr_nacl && tmr_tpg) {
+                        pr_debug("LUN_RESET: TMR caller fabric: %s"
+                                " initiator port %s\n",
+                                tmr_tpg->se_tpg_tfo->get_fabric_name(),
+                                tmr_nacl->initiatorname);
+                }
+        }
+        pr_debug("LUN_RESET: %s starting for [%s], tas: %d\n",
+                (preempt_and_abort_list) ? "Preempt" : "TMR",
+                dev->transport->name, tas);
+
+        core_tmr_drain_tmr_list(dev, tmr, preempt_and_abort_list);
+        core_tmr_drain_task_list(dev, prout_cmd, tmr_nacl, tas,
+                                preempt_and_abort_list);
+        core_tmr_drain_cmd_list(dev, prout_cmd, tmr_nacl, tas,
+                                preempt_and_abort_list);
         /*
          * Clear any legacy SPC-2 reservation when called during
          * LOGICAL UNIT RESET
@@ -378,3 +430,4 @@ int core_tmr_lun_reset(
                         dev->transport->name);
         return 0;
 }
+