isci: fix completion / abort path.

Corrected use of the request state_lock in the completion callback.

In the case where an abort (or reset) thread is trying to terminate an
I/O request, it sets the request state to "aborting" (or "terminating")
if the state is still "starting".  One of the bugs was to never set the
state to "completed".  Another was to not correctly recognize the
situation where the I/O had completed but the sas_task was still pending
callback to task_done - this was typically a problem in the LUN and
device reset cases.

It is now possible that we leave isci_task_abort_task() with
request->io_request_completion pointing to localy allocated
aborted_io_completion struct. It may result in a system crash.

Signed-off-by: Jeff Skirvin <jeffrey.d.skirvin@intel.com>
Signed-off-by: Maciej Trela <Maciej.Trela@intel.com>
Signed-off-by: Jacek Danecki <Jacek.Danecki@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

2 files changed, 129 insertions, 153 deletions

diff --git a/drivers/scsi/isci/request.c b/drivers/scsi/isci/request.c
index 8039f1c..c88e270 100644
--- a/drivers/scsi/isci/request.c
+++ b/drivers/scsi/isci/request.c
@@ -814,9 +814,8 @@ static void isci_task_save_for_upper_layer_completion(
 		break;
 
 	case isci_perform_aborted_io_completion:
-		/*
-		 * No notification because this request is already
-		 * in the abort path.
+		/* No notification to libsas because this request is
+		 * already in the abort path.
 		 */
 		dev_warn(&host->pdev->dev,
 			 "%s: Aborted - task = %p, response=%d, status=%d\n",
@@ -824,6 +823,19 @@ static void isci_task_save_for_upper_layer_completion(
 			 task,
 			 response,
 			 status);
+
+		/* Wake up whatever process was waiting for this
+		 * request to complete.
+		 */
+		WARN_ON(request->io_request_completion == NULL);
+
+		if (request->io_request_completion != NULL) {
+
+			/* Signal whoever is waiting that this
+			* request is complete.
+			*/
+			complete(request->io_request_completion);
+		}
 		break;
 
 	case isci_perform_error_io_completion:
@@ -847,7 +859,7 @@ static void isci_task_save_for_upper_layer_completion(
 			 response,
 			 status);
 
-		/* Add to the aborted list. */
+		/* Add to the error to libsas list. */
 		list_add(&request->completed_node,
 			 &host->requests_to_errorback);
 		break;
@@ -873,8 +885,6 @@ void isci_request_io_request_complete(
 	struct ssp_response_iu *resp_iu;
 	void *resp_buf;
 	unsigned long task_flags;
-	unsigned long state_flags;
-	struct completion *io_request_completion;
 	struct isci_remote_device *isci_device   = request->isci_device;
 	enum service_response response       = SAS_TASK_UNDELIVERED;
 	enum exec_status status         = SAS_ABORTED_TASK;
@@ -891,9 +901,8 @@ void isci_request_io_request_complete(
 		task->data_dir,
 		completion_status);
 
-	spin_lock_irqsave(&request->state_lock, state_flags);
+	spin_lock(&request->state_lock);
 	request_status = isci_request_get_state(request);
-	spin_unlock_irqrestore(&request->state_lock, state_flags);
 
 	/* Decode the request status.  Note that if the request has been
 	 * aborted by a task management function, we don't care
@@ -928,6 +937,8 @@ void isci_request_io_request_complete(
 
 		complete_to_host = isci_perform_aborted_io_completion;
 		/* This was an aborted request. */
+
+		spin_unlock(&request->state_lock);
 		break;
 
 	case aborting:
@@ -955,6 +966,8 @@ void isci_request_io_request_complete(
 		complete_to_host = isci_perform_aborted_io_completion;
 
 		/* This was an aborted request. */
+
+		spin_unlock(&request->state_lock);
 		break;
 
 	case terminating:
@@ -977,13 +990,20 @@ void isci_request_io_request_complete(
 		else
 			status = SAS_ABORTED_TASK;
 
-		complete_to_host = isci_perform_normal_io_completion;
+		complete_to_host = isci_perform_aborted_io_completion;
 
 		/* This was a terminated request. */
+
+		spin_unlock(&request->state_lock);
 		break;
 
 	default:
 
+		/* The request is done from an SCU HW perspective. */
+		request->status = completed;
+
+		spin_unlock(&request->state_lock);
+
 		/* This is an active request being completed from the core. */
 		switch (completion_status) {
 
@@ -1185,20 +1205,6 @@ void isci_request_io_request_complete(
 	 */
 	request->sci_request_handle = NULL;
 
-	/* Save possible completion ptr. */
-	io_request_completion = request->io_request_completion;
-
-	if (io_request_completion) {
-
-		/* This is inherantly a regular I/O request,
-		 * since we are currently in the regular
-		 * I/O completion callback function.
-		 * Signal whoever is waiting that this
-		 * request is complete.
-		 */
-		complete(io_request_completion);
-	}
-
 	isci_host_can_dequeue(isci_host, 1);
 }
 
diff --git a/drivers/scsi/isci/task.c b/drivers/scsi/isci/task.c
index 779f6cf..02c40c0 100644
--- a/drivers/scsi/isci/task.c
+++ b/drivers/scsi/isci/task.c
@@ -618,9 +618,6 @@ static enum isci_request_status isci_task_validate_request_to_abort(
 		old_state = isci_request_change_started_to_aborted(
 			isci_request, aborted_io_completion);
 
-		/* Only abort requests in the started state. */
-		if (old_state != started)
-			old_state = unallocated;
 	}
 
 	return old_state;
@@ -644,10 +641,23 @@ static void isci_request_cleanup_completed_loiterer(
 
 	spin_lock_irqsave(&isci_host->scic_lock, flags);
 	list_del_init(&isci_request->dev_node);
-	if (task != NULL)
-		task->lldd_task = NULL;
 	spin_unlock_irqrestore(&isci_host->scic_lock, flags);
 
+	if (task != NULL) {
+
+		spin_lock_irqsave(&task->task_state_lock, flags);
+		task->lldd_task = NULL;
+
+		isci_set_task_doneflags(task);
+
+		/* If this task is not in the abort path, call task_done. */
+		if (!(task->task_state_flags & SAS_TASK_STATE_ABORTED)) {
+
+			spin_unlock_irqrestore(&task->task_state_lock, flags);
+			task->task_done(task);
+		} else
+			spin_unlock_irqrestore(&task->task_state_lock, flags);
+	}
 	isci_request_free(isci_host, isci_request);
 }
 /**
@@ -684,17 +694,20 @@ static void isci_terminate_request_core(
 	spin_lock_irqsave(&isci_request->state_lock, flags);
 	request_status = isci_request_get_state(isci_request);
 
-	/* TMFs are in their own thread */
-	if ((isci_request->ttype == io_task) &&
-	    ((request_status == aborted) ||
-	     (request_status == aborting) ||
-	     (request_status == terminating)))
+	if ((isci_request->ttype == io_task) /* TMFs are in their own thread */
+	    && ((request_status == aborted)
+		|| (request_status == aborting)
+		|| (request_status == terminating)
+		|| (request_status == completed)
+		)
+	    ) {
+
 		/* The completion routine won't free a request in
 		 * the aborted/aborting/terminating state, so we do
 		 * it here.
 		 */
 		needs_cleanup_handling = true;
-
+	}
 	spin_unlock_irqrestore(&isci_request->state_lock, flags);
 
 	spin_lock_irqsave(&isci_host->scic_lock, flags);
@@ -765,10 +778,10 @@ static void isci_terminate_request(
 		new_request_state
 		);
 
-	spin_unlock_irqrestore(&isci_host->scic_lock, flags);
+	if ((old_state == started) || (old_state == completed)) {
 
-	if (old_state == started)
-		/* This request was not already being aborted. If it had been,
+		/* If the old_state is started:
+		 * This request was not already being aborted. If it had been,
 		 * then the aborting I/O (ie. the TMF request) would not be in
 		 * the aborting state, and thus would be terminated here.  Note
 		 * that since the TMF completion's call to the kernel function
@@ -777,9 +790,15 @@ static void isci_terminate_request(
 		 * special wait here for already aborting requests - the
 		 * termination of the TMF request will force the request
 		 * to finish it's already started terminate.
+		 *
+		 * If old_state == completed:
+		 * This request completed from the SCU hardware perspective
+		 * and now just needs cleaning up in terms of freeing the
+		 * request and potentially calling up to libsas.
 		 */
 		isci_terminate_request_core(isci_host, isci_device,
 					    isci_request, &request_completion);
+	}
 }
 
 /**
@@ -863,10 +882,6 @@ void isci_terminate_pending_requests(
 			isci_terminate_request(isci_host, isci_device,
 					       isci_request, new_request_state
 					       );
-
-			/* Set the 'done' state on the task. */
-			if (task)
-				isci_task_all_done(task);
 		}
 	} while (!done);
 }
@@ -1067,13 +1082,15 @@ static void isci_abort_task_process_cb(
 int isci_task_abort_task(struct sas_task *task)
 {
 	DECLARE_COMPLETION_ONSTACK(aborted_io_completion);
-	struct isci_request *old_request = NULL;
+	struct isci_request       *old_request = NULL;
+	enum isci_request_status  old_state;
 	struct isci_remote_device *isci_device = NULL;
-	struct isci_host *isci_host = NULL;
-	struct isci_tmf tmf;
-	int ret = TMF_RESP_FUNC_FAILED;
-	unsigned long flags;
-	bool any_dev_reset, device_stopping;
+	struct isci_host          *isci_host = NULL;
+	struct isci_tmf           tmf;
+	int                       ret = TMF_RESP_FUNC_FAILED;
+	unsigned long             flags;
+	bool                      any_dev_reset = false;
+	bool                      device_stopping;
 
 	/* Get the isci_request reference from the task.  Note that
 	 * this check does not depend on the pending request list
@@ -1093,21 +1110,6 @@ int isci_task_abort_task(struct sas_task *task)
 	device_stopping = (isci_device->status == isci_stopping)
 			  || (isci_device->status == isci_stopped);
 
-#ifdef NOMORE
-	/* This abort task function is the first stop of the libsas error
-	 * handler thread. Since libsas is executing in a thread with a
-	 * referernce to the "task" parameter, that task cannot be completed
-	 * directly back to the upper layers.  In order to make sure that
-	 * the task is managed correctly if this abort task fails, set the
-	 * "SAS_TASK_STATE_ABORTED" bit now such that completions up the
-	 * stack will be intercepted and only allowed to happen in the
-	 * libsas SCSI error handler thread.
-	 */
-	spin_lock_irqsave(&task->task_state_lock, flags);
-	task->task_state_flags |= SAS_TASK_STATE_ABORTED;
-	spin_unlock_irqrestore(&task->task_state_lock, flags);
-#endif  /* NOMORE */
-
 	/* This version of the driver will fail abort requests for
 	 * SATA/STP.  Failing the abort request this way will cause the
 	 * SCSI error handler thread to escalate to LUN reset
@@ -1123,35 +1125,27 @@ int isci_task_abort_task(struct sas_task *task)
 	dev_dbg(&isci_host->pdev->dev,
 		"%s: old_request == %p\n", __func__, old_request);
 
+	if (!device_stopping)
+		any_dev_reset = isci_device_is_reset_pending(isci_host,isci_device);
+
 	spin_lock_irqsave(&task->task_state_lock, flags);
 
 	/* Don't do resets to stopping devices. */
-	if (device_stopping)
-		task->task_state_flags &= ~SAS_TASK_NEED_DEV_RESET;
+	if (device_stopping) {
 
-	/* See if there is a pending device reset for this device. */
-	any_dev_reset = task->task_state_flags & SAS_TASK_NEED_DEV_RESET;
-
-	spin_unlock_irqrestore(&task->task_state_lock, flags);
+		task->task_state_flags &= ~SAS_TASK_NEED_DEV_RESET;
+		any_dev_reset = false;
 
-	if ((isci_device != NULL) && !device_stopping)
+	} else	/* See if there is a pending device reset for this device. */
 		any_dev_reset = any_dev_reset
-				|| isci_device_is_reset_pending(isci_host,
-								isci_device
-								);
+			|| (task->task_state_flags & SAS_TASK_NEED_DEV_RESET);
 
 	/* If the extraction of the request reference from the task
 	 * failed, then the request has been completed (or if there is a
 	 * pending reset then this abort request function must be failed
 	 * in order to escalate to the target reset).
 	 */
-	if ((old_request == NULL) ||
-	    ((old_request != NULL) &&
-	     (old_request->sci_request_handle == NULL) &&
-	     (old_request->complete_in_target)) ||
-	     any_dev_reset) {
-
-		spin_lock_irqsave(&task->task_state_lock, flags);
+	if ((old_request == NULL) || any_dev_reset) {
 
 		/* If the device reset task flag is set, fail the task
 		 * management request.  Otherwise, the original request
@@ -1164,6 +1158,11 @@ int isci_task_abort_task(struct sas_task *task)
 			 */
 			task->task_state_flags &= ~SAS_TASK_STATE_DONE;
 
+			/* Make the reset happen as soon as possible. */
+			task->task_state_flags |= SAS_TASK_NEED_DEV_RESET;
+
+			spin_unlock_irqrestore(&task->task_state_lock, flags);
+
 			/* Fail the task management request in order to
 			 * escalate to the target reset.
 			 */
@@ -1176,13 +1175,8 @@ int isci_task_abort_task(struct sas_task *task)
 				"task %p on dev %p\n",
 				__func__, task, isci_device);
 
-		} else {
-			ret = TMF_RESP_FUNC_COMPLETE;
-
-			dev_dbg(&isci_host->pdev->dev,
-				"%s: abort task not needed for %p\n",
-				__func__, task);
 
+		} else {
 			/* The request has already completed and there
 			 * is nothing to do here other than to set the task
 			 * done bit, and indicate that the task abort function
@@ -1190,89 +1184,65 @@ int isci_task_abort_task(struct sas_task *task)
 			 */
 			isci_set_task_doneflags(task);
 
-			/* Set the abort bit to make sure that libsas sticks the
-			 * task in the completed task queue.
-			 */
-/*			task->task_state_flags |= SAS_TASK_STATE_ABORTED; */
+			spin_unlock_irqrestore(&task->task_state_lock, flags);
 
-			/* Check for the situation where the request was
-			 * left around on the device list but the
-			 * request already completed.
-			 */
-			if (old_request && !old_request->sci_request_handle) {
+			ret = TMF_RESP_FUNC_COMPLETE;
 
-				isci_request_cleanup_completed_loiterer(
-					isci_host, isci_device, old_request
-					);
-			}
+			dev_dbg(&isci_host->pdev->dev,
+				"%s: abort task not needed for %p\n",
+				__func__, task);
 		}
-		spin_unlock_irqrestore(&task->task_state_lock, flags);
 
 		return ret;
 	}
+	else
+		spin_unlock_irqrestore(&task->task_state_lock, flags);
 
 	spin_lock_irqsave(&isci_host->scic_lock, flags);
 
-	/* Sanity check the request status, and set the I/O kernel completion
+	/* Check the request status and change to "aborting" if currently
+	 * "starting"; if true then set the I/O kernel completion
 	 * struct that will be triggered when the request completes.
 	 */
-	if (isci_task_validate_request_to_abort(
-		    old_request,
-		    isci_host,
-		    isci_device,
-		    &aborted_io_completion)
-	    == unallocated) {
-		dev_dbg(&isci_host->pdev->dev,
-			"%s: old_request not valid for device = %p\n",
-			__func__,
-			isci_device);
-		old_request = NULL;
-	}
-
-	if (!old_request) {
-
-		/* There is no isci_request attached to the sas_task.
-		 * It must have been completed and detached.
-		 */
-		dev_dbg(&isci_host->pdev->dev,
-			"%s: old_request == NULL\n",
-			__func__);
+	old_state = isci_task_validate_request_to_abort(
+				old_request, isci_host, isci_device,
+				&aborted_io_completion);
+	if ((old_state != started) && (old_state != completed)) {
 
 		spin_unlock_irqrestore(&isci_host->scic_lock, flags);
 
-		/* Set the state on the task. */
-		isci_task_all_done(task);
+		/* The request was already being handled by someone else (because
+		* they got to set the state away from started).
+		*/
+		dev_dbg(&isci_host->pdev->dev,
+			"%s:  device = %p; old_request %p already being aborted\n",
+			__func__,
+			isci_device, old_request);
 
 		return TMF_RESP_FUNC_COMPLETE;
 	}
-	if (task->task_proto == SAS_PROTOCOL_SMP || device_stopping) {
-
-		if (device_stopping)
-			dev_dbg(&isci_host->pdev->dev,
-				"%s: device is stopping, thus no TMF\n",
-				__func__);
-		else
-			dev_dbg(&isci_host->pdev->dev,
-				"%s: request is SMP, thus no TMF\n",
-				__func__);
-
-		old_request->complete_in_target = true;
+	if ((task->task_proto == SAS_PROTOCOL_SMP)
+	    || device_stopping
+	    || old_request->complete_in_target
+	    ) {
 
 		spin_unlock_irqrestore(&isci_host->scic_lock, flags);
 
+		dev_dbg(&isci_host->pdev->dev,
+			"%s: SMP request (%d)"
+			" or device is stopping (%d)"
+			" or complete_in_target (%d), thus no TMF\n",
+			__func__, (task->task_proto == SAS_PROTOCOL_SMP),
+			device_stopping, old_request->complete_in_target);
+
 		/* Set the state on the task. */
 		isci_task_all_done(task);
 
 		ret = TMF_RESP_FUNC_COMPLETE;
 
 		/* Stopping and SMP devices are not sent a TMF, and are not
-		 * reset, but the outstanding I/O request is terminated here.
-		 *
-		 * Clean up the request on our side, and wait for the aborted
-		 * I/O to complete.
+		 * reset, but the outstanding I/O request is terminated below.
 		 */
-		isci_terminate_request_core(isci_host, isci_device, old_request,
-					    &aborted_io_completion);
 	} else {
 		/* Fill in the tmf stucture */
 		isci_task_build_tmf(&tmf, isci_device, isci_tmf_ssp_task_abort,
@@ -1288,23 +1258,23 @@ int isci_task_abort_task(struct sas_task *task)
 		ret = isci_task_execute_tmf(isci_host, &tmf,
 					    ISCI_ABORT_TASK_TIMEOUT_MS);
 
-		if (ret == TMF_RESP_FUNC_COMPLETE) {
-			old_request->complete_in_target = true;
-
-			/* Clean up the request on our side, and wait for the aborted I/O to
-			 * complete.
-			 */
-			isci_terminate_request_core(isci_host, isci_device, old_request,
-						    &aborted_io_completion);
-
-			/* Set the state on the task. */
-			isci_task_all_done(task);
-		} else
+		if (ret != TMF_RESP_FUNC_COMPLETE)
 			dev_err(&isci_host->pdev->dev,
 				"%s: isci_task_send_tmf failed\n",
 				__func__);
 	}
+	if (ret == TMF_RESP_FUNC_COMPLETE) {
+		old_request->complete_in_target = true;
+
+		/* Clean up the request on our side, and wait for the aborted I/O to
+		* complete.
+		*/
+		isci_terminate_request_core(isci_host, isci_device, old_request,
+					    &aborted_io_completion);
+	}
 
+	/* Make sure we do not leave a reference to aborted_io_completion */
+	old_request->io_request_completion = NULL;
 	return ret;
 }