[SCSI] libsas: Delay issuing ABORT TASK TMF until the error handler

sas_task_abort() should simply abort the upper-level SCSI command and wait
until the error handler to send the actual ABORT TASK command.  By
deferring things to the EH we simplify the concurrency coordination and
eliminate some race conditions.  Note that sas_task_abort has a few hooks
to handle libsas internal commands properly too.

Also rename do_sas_task_abort to __sas_task_abort just in case we really
want to abort the task *right now* and we don't have a scsi_cmnd attached
to the command.  This is a hook for libata internal commands to abort.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/libsas/sas_scsi_host.c

@@ -560,6 +560,7 @@ enum scsi_eh_timer_return sas_scsi_timed_out(struct scsi_cmnd *cmd)
 	}
 
 	spin_lock_irqsave(&task->task_state_lock, flags);
+	BUG_ON(task->task_state_flags & SAS_TASK_STATE_ABORTED);
 	if (task->task_state_flags & SAS_TASK_STATE_DONE) {
 		spin_unlock_irqrestore(&task->task_state_lock, flags);
 		SAS_DPRINTK("command 0x%p, task 0x%p, timed out: EH_HANDLED\n",
@@ -830,44 +831,42 @@ void sas_shutdown_queue(struct sas_ha_struct *sas_ha)
 	spin_unlock_irqrestore(&core->task_queue_lock, flags);
 }
 
-static int do_sas_task_abort(struct sas_task *task)
+/*
+ * Call the LLDD task abort routine directly.  This function is intended for
+ * use by upper layers that need to tell the LLDD to abort a task.
+ */
+int __sas_task_abort(struct sas_task *task)
 {
-	struct scsi_cmnd *sc = task->uldd_task;
 	struct sas_internal *si =
 		to_sas_internal(task->dev->port->ha->core.shost->transportt);
 	unsigned long flags;
 	int res;
 
 	spin_lock_irqsave(&task->task_state_lock, flags);
-	if (task->task_state_flags & SAS_TASK_STATE_ABORTED) {
+	if (task->task_state_flags & SAS_TASK_STATE_ABORTED ||
+	    task->task_state_flags & SAS_TASK_STATE_DONE) {
 		spin_unlock_irqrestore(&task->task_state_lock, flags);
-		SAS_DPRINTK("%s: Task %p already aborted.\n", __FUNCTION__,
+		SAS_DPRINTK("%s: Task %p already finished.\n", __FUNCTION__,
 			    task);
 		return 0;
 	}
-
-	if (!(task->task_state_flags & SAS_TASK_STATE_DONE))
-		task->task_state_flags |= SAS_TASK_STATE_ABORTED;
+	task->task_state_flags |= SAS_TASK_STATE_ABORTED;
 	spin_unlock_irqrestore(&task->task_state_lock, flags);
 
 	if (!si->dft->lldd_abort_task)
 		return -ENODEV;
 
 	res = si->dft->lldd_abort_task(task);
+
+	spin_lock_irqsave(&task->task_state_lock, flags);
 	if ((task->task_state_flags & SAS_TASK_STATE_DONE) ||
 	    (res == TMF_RESP_FUNC_COMPLETE))
 	{
-		/* SMP commands don't have scsi_cmds(?) */
-		if (!sc) {
-			task->task_done(task);
-			return 0;
-		}
-		scsi_req_abort_cmd(sc);
-		scsi_schedule_eh(sc->device->host);
+		spin_unlock_irqrestore(&task->task_state_lock, flags);
+		task->task_done(task);
 		return 0;
 	}
 
-	spin_lock_irqsave(&task->task_state_lock, flags);
 	if (!(task->task_state_flags & SAS_TASK_STATE_DONE))
 		task->task_state_flags &= ~SAS_TASK_STATE_ABORTED;
 	spin_unlock_irqrestore(&task->task_state_lock, flags);
@@ -875,17 +874,24 @@ static int do_sas_task_abort(struct sas_task *task)
 	return -EAGAIN;
 }
 
-void sas_task_abort(struct work_struct *work)
+/*
+ * Tell an upper layer that it needs to initiate an abort for a given task.
+ * This should only ever be called by an LLDD.
+ */
+void sas_task_abort(struct sas_task *task)
 {
-	struct sas_task *task =
-		container_of(work, struct sas_task, abort_work);
-	int i;
+	struct scsi_cmnd *sc = task->uldd_task;
 
-	for (i = 0; i < 5; i++)
-		if (!do_sas_task_abort(task))
+	/* Escape for libsas internal commands */
+	if (!sc) {
+		if (!del_timer(&task->timer))
 			return;
+		task->timer.function(task->timer.data);
+		return;
+	}
 
-	SAS_DPRINTK("%s: Could not kill task!\n", __FUNCTION__);
+	scsi_req_abort_cmd(sc);
+	scsi_schedule_eh(sc->device->host);
 }
 
 EXPORT_SYMBOL_GPL(sas_queuecommand);
@@ -895,6 +901,7 @@ EXPORT_SYMBOL_GPL(sas_slave_destroy);
 EXPORT_SYMBOL_GPL(sas_change_queue_depth);
 EXPORT_SYMBOL_GPL(sas_change_queue_type);
 EXPORT_SYMBOL_GPL(sas_bios_param);
+EXPORT_SYMBOL_GPL(__sas_task_abort);
 EXPORT_SYMBOL_GPL(sas_task_abort);
 EXPORT_SYMBOL_GPL(sas_phy_reset);
 EXPORT_SYMBOL_GPL(sas_phy_enable);

include/scsi/libsas.h

@@ -650,6 +650,7 @@ void sas_unregister_dev(struct domain_device *);
 
 void sas_init_dev(struct domain_device *);
 
-void sas_task_abort(struct work_struct *);
+void sas_task_abort(struct sas_task *);
+int __sas_task_abort(struct sas_task *);
 
 #endif /* _SASLIB_H_ */