[PATCH v2 4/4] staging: greybus: loopback: convert loopback to use generic async operations

Bryan O'Donoghue pure.logic at nexus-software.ie
Mon Nov 6 01:26:11 UTC 2017


Loopback has its own internal method for tracking and timing out
asynchronous operations however previous patches make it possible to use
functionality provided by operation.c to do this instead. Using the code in
operation.c means we can completely subtract the timer, the work-queue, the
kref and the cringe-worthy 'pending' flag. The completion callback
triggered by operation.c will provide an authoritative result code -
including -ETIMEDOUT for asynchronous operations.

Signed-off-by: Bryan O'Donoghue <pure.logic at nexus-software.ie>
Cc: Johan Hovold <johan at kernel.org>
Cc: Alex Elder <elder at kernel.org>
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Cc: Kees Cook <keescook at chromium.org>
Cc: Mitch Tasman <tasman at leaflabs.com>
Cc: greybus-dev at lists.linaro.org
Cc: devel at driverdev.osuosl.org
Cc: linux-kernel at vger.kernel.org
---
 drivers/staging/greybus/loopback.c | 168 +++++++------------------------------
 1 file changed, 29 insertions(+), 139 deletions(-)

diff --git a/drivers/staging/greybus/loopback.c b/drivers/staging/greybus/loopback.c
index 9c5980c..6d51998 100644
--- a/drivers/staging/greybus/loopback.c
+++ b/drivers/staging/greybus/loopback.c
@@ -59,11 +59,6 @@ struct gb_loopback_async_operation {
 	struct gb_loopback *gb;
 	struct gb_operation *operation;
 	ktime_t ts;
-	struct timer_list timer;
-	struct list_head entry;
-	struct work_struct work;
-	struct kref kref;
-	bool pending;
 	int (*completion)(struct gb_loopback_async_operation *op_async);
 };
 
@@ -427,56 +422,6 @@ static int gb_loopback_operation_sync(struct gb_loopback *gb, int type,
 	return ret;
 }
 
-static void __gb_loopback_async_operation_destroy(struct kref *kref)
-{
-	struct gb_loopback_async_operation *op_async;
-
-	op_async = container_of(kref, struct gb_loopback_async_operation, kref);
-
-	list_del(&op_async->entry);
-	if (op_async->operation)
-		gb_operation_put(op_async->operation);
-	atomic_dec(&op_async->gb->outstanding_operations);
-	wake_up(&op_async->gb->wq_completion);
-	kfree(op_async);
-}
-
-static void gb_loopback_async_operation_get(struct gb_loopback_async_operation
-					    *op_async)
-{
-	kref_get(&op_async->kref);
-}
-
-static void gb_loopback_async_operation_put(struct gb_loopback_async_operation
-					    *op_async)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&gb_dev.lock, flags);
-	kref_put(&op_async->kref, __gb_loopback_async_operation_destroy);
-	spin_unlock_irqrestore(&gb_dev.lock, flags);
-}
-
-static struct gb_loopback_async_operation *
-	gb_loopback_operation_find(u16 id)
-{
-	struct gb_loopback_async_operation *op_async;
-	bool found = false;
-	unsigned long flags;
-
-	spin_lock_irqsave(&gb_dev.lock, flags);
-	list_for_each_entry(op_async, &gb_dev.list_op_async, entry) {
-		if (op_async->operation->id == id) {
-			gb_loopback_async_operation_get(op_async);
-			found = true;
-			break;
-		}
-	}
-	spin_unlock_irqrestore(&gb_dev.lock, flags);
-
-	return found ? op_async : NULL;
-}
-
 static void gb_loopback_async_wait_all(struct gb_loopback *gb)
 {
 	wait_event(gb->wq_completion,
@@ -488,83 +433,41 @@ static void gb_loopback_async_operation_callback(struct gb_operation *operation)
 	struct gb_loopback_async_operation *op_async;
 	struct gb_loopback *gb;
 	ktime_t te;
-	bool err = false;
+	int result;
 
 	te = ktime_get();
-	op_async = gb_loopback_operation_find(operation->id);
-	if (!op_async)
-		return;
-
+	result = gb_operation_result(operation);
+	op_async = gb_operation_get_data(operation);
 	gb = op_async->gb;
+
 	mutex_lock(&gb->mutex);
 
-	if (!op_async->pending || gb_operation_result(operation)) {
-		err = true;
-	} else {
-		if (op_async->completion)
-			if (op_async->completion(op_async))
-				err = true;
-	}
+	if (!result && op_async->completion)
+		result = op_async->completion(op_async);
 
-	if (!err)
+	if (!result) {
 		gb->elapsed_nsecs = gb_loopback_calc_latency(op_async->ts, te);
-
-	if (op_async->pending) {
-		if (err)
-			gb->error++;
-		gb->iteration_count++;
-		op_async->pending = false;
-		del_timer_sync(&op_async->timer);
-		gb_loopback_async_operation_put(op_async);
-		gb_loopback_calculate_stats(gb, err);
+	} else {
+		gb->error++;
+		if (result == -ETIMEDOUT)
+			gb->requests_timedout++;
 	}
-	mutex_unlock(&gb->mutex);
-
-	dev_dbg(&gb->connection->bundle->dev, "complete operation %d\n",
-		operation->id);
-
-	gb_loopback_async_operation_put(op_async);
-}
-
-static void gb_loopback_async_operation_work(struct work_struct *work)
-{
-	struct gb_loopback *gb;
-	struct gb_operation *operation;
-	struct gb_loopback_async_operation *op_async;
 
-	op_async = container_of(work, struct gb_loopback_async_operation, work);
-	gb = op_async->gb;
-	operation = op_async->operation;
+	gb->iteration_count++;
+	gb_loopback_calculate_stats(gb, result);
 
-	mutex_lock(&gb->mutex);
-	if (op_async->pending) {
-		gb->requests_timedout++;
-		gb->error++;
-		gb->iteration_count++;
-		op_async->pending = false;
-		gb_loopback_async_operation_put(op_async);
-		gb_loopback_calculate_stats(gb, true);
-	}
 	mutex_unlock(&gb->mutex);
 
-	dev_dbg(&gb->connection->bundle->dev, "timeout operation %d\n",
+	dev_dbg(&gb->connection->bundle->dev, "complete operation %d\n",
 		operation->id);
 
-	gb_operation_cancel(operation, -ETIMEDOUT);
-	gb_loopback_async_operation_put(op_async);
-}
-
-static void gb_loopback_async_operation_timeout(unsigned long data)
-{
-	struct gb_loopback_async_operation *op_async;
-	u16 id = data;
+	/* Wake up waiters */
+	atomic_dec(&op_async->gb->outstanding_operations);
+	wake_up(&gb->wq_completion);
 
-	op_async = gb_loopback_operation_find(id);
-	if (!op_async) {
-		pr_err("operation %d not found - time out ?\n", id);
-		return;
-	}
-	schedule_work(&op_async->work);
+	/* Release resources */
+	gb_operation_put(operation);
+	kfree(op_async);
 }
 
 static int gb_loopback_async_operation(struct gb_loopback *gb, int type,
@@ -575,15 +478,11 @@ static int gb_loopback_async_operation(struct gb_loopback *gb, int type,
 	struct gb_loopback_async_operation *op_async;
 	struct gb_operation *operation;
 	int ret;
-	unsigned long flags;
 
 	op_async = kzalloc(sizeof(*op_async), GFP_KERNEL);
 	if (!op_async)
 		return -ENOMEM;
 
-	INIT_WORK(&op_async->work, gb_loopback_async_operation_work);
-	kref_init(&op_async->kref);
-
 	operation = gb_operation_create(gb->connection, type, request_size,
 					response_size, GFP_KERNEL);
 	if (!operation) {
@@ -594,33 +493,24 @@ static int gb_loopback_async_operation(struct gb_loopback *gb, int type,
 	if (request_size)
 		memcpy(operation->request->payload, request, request_size);
 
+	gb_operation_set_data(operation, op_async);
+
 	op_async->gb = gb;
 	op_async->operation = operation;
 	op_async->completion = completion;
 
-	spin_lock_irqsave(&gb_dev.lock, flags);
-	list_add_tail(&op_async->entry, &gb_dev.list_op_async);
-	spin_unlock_irqrestore(&gb_dev.lock, flags);
-
 	op_async->ts = ktime_get();
-	op_async->pending = true;
+
 	atomic_inc(&gb->outstanding_operations);
 	ret = gb_operation_request_send(operation,
 					gb_loopback_async_operation_callback,
-					0,
+					jiffies_to_msecs(gb->jiffy_timeout),
 					GFP_KERNEL);
-	if (ret)
-		goto error;
-
-	setup_timer(&op_async->timer, gb_loopback_async_operation_timeout,
-			(unsigned long)operation->id);
-	op_async->timer.expires = jiffies + gb->jiffy_timeout;
-	add_timer(&op_async->timer);
-
-	goto done;
-error:
-	gb_loopback_async_operation_put(op_async);
-done:
+	if (ret) {
+		atomic_dec(&gb->outstanding_operations);
+		gb_operation_put(operation);
+		kfree(op_async);
+	}
 	return ret;
 }
 
-- 
2.7.4



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