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Commit 4410bacb authored by Pratham Pratap's avatar Pratham Pratap
Browse files

USB: f_mtp: Improve MTP write throughput 



Commit fc71db86987e8 ("USB: f_mtp: Perform vfs_write under mutex
protection) introduces mutex protection to avoid request buffer
freed while vfs_write or copy_to_user happens. This introduced
significant amount of delay for mtp_write throughput. Fix
this by reverting the patch.

Change-Id: I97e513a175b2a6691f42f8e762e2f8fd9bdf35f1
Signed-off-by: default avatarPratham Pratap <prathampratap@codeaurora.org>
parent 06c68199

drivers/usb/gadget/function/f_mtp.c

+0 −36
Original line number Diff line number Diff line
@@ -150,7 +150,6 @@ struct mtp_dev { 
	} perf[MAX_ITERATION];

	unsigned int dbg_read_index;

	unsigned int dbg_write_index;

	struct mutex  read_mutex;

};



static void *_mtp_ipc_log;
@@ -650,18 +649,11 @@ static ssize_t mtp_read(struct file *fp, char __user *buf, 
	dev->state = STATE_BUSY;

	spin_unlock_irq(&dev->lock);



	mutex_lock(&dev->read_mutex);

	if (dev->state == STATE_OFFLINE) {

		r = -EIO;

		mutex_unlock(&dev->read_mutex);

		goto done;

	}

requeue_req:

	/* queue a request */

	req = dev->rx_req[0];

	req->length = len;

	dev->rx_done = 0;

	mutex_unlock(&dev->read_mutex);

	ret = usb_ep_queue(dev->ep_out, req, GFP_KERNEL);

	if (ret < 0) {

		r = -EIO;
@@ -687,7 +679,6 @@ static ssize_t mtp_read(struct file *fp, char __user *buf, 
		usb_ep_dequeue(dev->ep_out, req);

		goto done;

	}

	mutex_lock(&dev->read_mutex);

	if (dev->state == STATE_BUSY) {

		/* If we got a 0-len packet, throw it back and try again. */

		if (req->actual == 0)
@@ -701,7 +692,6 @@ static ssize_t mtp_read(struct file *fp, char __user *buf, 
	} else

		r = -EIO;



	mutex_unlock(&dev->read_mutex);

done:

	spin_lock_irq(&dev->lock);

	if (dev->state == STATE_CANCELED)
@@ -949,12 +939,6 @@ static void receive_file_work(struct work_struct *data) 


	while (count > 0 || write_req) {

		if (count > 0) {

			mutex_lock(&dev->read_mutex);

			if (dev->state == STATE_OFFLINE) {

				r = -EIO;

				mutex_unlock(&dev->read_mutex);

				break;

			}

			/* queue a request */

			read_req = dev->rx_req[cur_buf];

			cur_buf = (cur_buf + 1) % RX_REQ_MAX;
@@ -963,7 +947,6 @@ static void receive_file_work(struct work_struct *data) 
			read_req->length = mtp_rx_req_len;



			dev->rx_done = 0;

			mutex_unlock(&dev->read_mutex);

			ret = usb_ep_queue(dev->ep_out, read_req, GFP_KERNEL);

			if (ret < 0) {

				r = -EIO;
@@ -976,25 +959,17 @@ static void receive_file_work(struct work_struct *data) 
		if (write_req) {

			mtp_log("rx %pK %d\n", write_req, write_req->actual);

			start_time = ktime_get();

			mutex_lock(&dev->read_mutex);

			if (dev->state == STATE_OFFLINE) {

				r = -EIO;

				mutex_unlock(&dev->read_mutex);

				break;

			}

			ret = vfs_write(filp, write_req->buf, write_req->actual,

				&offset);

			mtp_log("vfs_write %d\n", ret);

			if (ret != write_req->actual) {

				r = -EIO;

				mutex_unlock(&dev->read_mutex);

				if (dev->state != STATE_OFFLINE)

					dev->state = STATE_ERROR;

				if (read_req && !dev->rx_done)

					usb_ep_dequeue(dev->ep_out, read_req);

				break;

			}

			mutex_unlock(&dev->read_mutex);

			dev->perf[dev->dbg_write_index].vfs_wtime =

				ktime_to_us(ktime_sub(ktime_get(), start_time));

			dev->perf[dev->dbg_write_index].vfs_wbytes = ret;
@@ -1022,12 +997,6 @@ static void receive_file_work(struct work_struct *data) 
				break;

			}



			mutex_lock(&dev->read_mutex);

			if (dev->state == STATE_OFFLINE) {

				r = -EIO;

				mutex_unlock(&dev->read_mutex);

				break;

			}

			/* Check if we aligned the size due to MTU constraint */

			if (count < read_req->length)

				read_req->actual = (read_req->actual > count ?
@@ -1048,7 +1017,6 @@ static void receive_file_work(struct work_struct *data) 


			write_req = read_req;

			read_req = NULL;

			mutex_unlock(&dev->read_mutex);

		}

	}
@@ -1501,14 +1469,12 @@ mtp_function_unbind(struct usb_configuration *c, struct usb_function *f) 
	fi_mtp = container_of(f->fi, struct mtp_instance, func_inst);

	mtp_string_defs[INTERFACE_STRING_INDEX].id = 0;

	mtp_log("dev: %pK\n", dev);

	mutex_lock(&dev->read_mutex);

	while ((req = mtp_req_get(dev, &dev->tx_idle)))

		mtp_request_free(req, dev->ep_in);

	for (i = 0; i < RX_REQ_MAX; i++)

		mtp_request_free(dev->rx_req[i], dev->ep_out);

	while ((req = mtp_req_get(dev, &dev->intr_idle)))

		mtp_request_free(req, dev->ep_intr);

	mutex_unlock(&dev->read_mutex);

	spin_lock_irq(&dev->lock);

	dev->state = STATE_OFFLINE;

	dev->cdev = NULL;
@@ -1853,8 +1819,6 @@ struct usb_function_instance *alloc_inst_mtp_ptp(bool mtp_config) 
	usb_os_desc_prepare_interf_dir(&fi_mtp->func_inst.group, 1,

					descs, names, THIS_MODULE);



	mutex_init(&fi_mtp->dev->read_mutex);



	return  &fi_mtp->func_inst;

}

EXPORT_SYMBOL_GPL(alloc_inst_mtp_ptp);