patch "usb: gadget: loopback: Fix looping back logic implementation" added to usb-next

patch "usb: gadget: loopback: Fix looping back logic implementation" added to usb-next

[gregkh]

This is a note to let you know that I've just added the patch titled

    usb: gadget: loopback: Fix looping back logic implementation

to my usb git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-next branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will also be merged in the next major kernel release
during the merge window.

If you have any questions about this process, please let me know.


>From 91c42b0da8e353697c9b49fe541056c5d0518c49 Mon Sep 17 00:00:00 2001
From: Krzysztof Opasiak <k.opasiak@samsung.com>
Date: Wed, 14 Oct 2015 22:49:40 +0200
Subject: usb: gadget: loopback: Fix looping back logic implementation

Since commit e0857ce58e8658657f5f12fe25272b93cfeb16aa
("usb: gadget: loopback: don't queue requests to bogus endpoints")

Loopback function is not realy working as that commit removed
all looping back logic. After that commit ep-out works like
/dev/null and ep-in works like /dev/zero.

This commit fix this issue by allocating set of out requests
and set of in requests but each out req shares buffer with
one in req:

out_req->buf ---> buf <--- in_req.buf
out_req->context <---> in_req.context

The completion routine simply  enqueue the suitable req in
an oposite direction.

Cc: <stable@vger.kernel.org> # 3.18+
Fixes: e0857ce58e8658657f5f12fe25272b93cfeb16aa
("usb: gadget: loopback: don't queue requests to bogus endpoints")

Signed-off-by: Krzysztof Opasiak <k.opasiak@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
---
 drivers/usb/gadget/function/f_loopback.c | 131 ++++++++++++++++++++++---------
 1 file changed, 92 insertions(+), 39 deletions(-)

diff --git a/drivers/usb/gadget/function/f_loopback.c b/drivers/usb/gadget/function/f_loopback.c
index 79e284bba059..6b2102bc0699 100644
--- a/drivers/usb/gadget/function/f_loopback.c
+++ b/drivers/usb/gadget/function/f_loopback.c
@@ -243,22 +243,38 @@ static void loopback_complete(struct usb_ep *ep, struct usb_request *req)
 	int			status = req->status;
 
 	switch (status) {
-
 	case 0:				/* normal completion? */
 		if (ep == loop->out_ep) {
-			req->zero = (req->actual < req->length);
-			req->length = req->actual;
+			/*
+			 * We received some data from the host so let's
+			 * queue it so host can read the from our in ep
+			 */
+			struct usb_request *in_req = req->context;
+
+			in_req->zero = (req->actual < req->length);
+			in_req->length = req->actual;
+			ep = loop->in_ep;
+			req = in_req;
+		} else {
+			/*
+			 * We have just looped back a bunch of data
+			 * to host. Now let's wait for some more data.
+			 */
+			req = req->context;
+			ep = loop->out_ep;
 		}
 
-		/* queue the buffer for some later OUT packet */
-		req->length = loop->buflen;
+		/* queue the buffer back to host or for next bunch of data */
 		status = usb_ep_queue(ep, req, GFP_ATOMIC);
-		if (status == 0)
+		if (status == 0) {
 			return;
+		} else {
+			ERROR(cdev, "Unable to loop back buffer to %s: %d\n",
+			      ep->name, status);
+			goto free_req;
+		}
 
 		/* "should never get here" */
-		/* FALLTHROUGH */
-
 	default:
 		ERROR(cdev, "%s loop complete --> %d, %d/%d\n", ep->name,
 				status, req->actual, req->length);
@@ -272,6 +288,10 @@ static void loopback_complete(struct usb_ep *ep, struct usb_request *req)
 	case -ECONNABORTED:		/* hardware forced ep reset */
 	case -ECONNRESET:		/* request dequeued */
 	case -ESHUTDOWN:		/* disconnect from host */
+free_req:
+		usb_ep_free_request(ep == loop->in_ep ?
+				    loop->out_ep : loop->in_ep,
+				    req->context);
 		free_ep_req(ep, req);
 		return;
 	}
@@ -293,50 +313,72 @@ static inline struct usb_request *lb_alloc_ep_req(struct usb_ep *ep, int len)
 	return alloc_ep_req(ep, len, loop->buflen);
 }
 
-static int enable_endpoint(struct usb_composite_dev *cdev, struct f_loopback *loop,
-		struct usb_ep *ep)
+static int alloc_requests(struct usb_composite_dev *cdev,
+			  struct f_loopback *loop)
 {
-	struct usb_request			*req;
-	unsigned				i;
-	int					result;
-
-	/*
-	 * one endpoint writes data back IN to the host while another endpoint
-	 * just reads OUT packets
-	 */
-	result = config_ep_by_speed(cdev->gadget, &(loop->function), ep);
-	if (result)
-		goto fail0;
-	result = usb_ep_enable(ep);
-	if (result < 0)
-		goto fail0;
-	ep->driver_data = loop;
+	struct usb_request *in_req, *out_req;
+	int i;
+	int result = 0;
 
 	/*
 	 * allocate a bunch of read buffers and queue them all at once.
-	 * we buffer at most 'qlen' transfers; fewer if any need more
-	 * than 'buflen' bytes each.
+	 * we buffer at most 'qlen' transfers; We allocate buffers only
+	 * for out transfer and reuse them in IN transfers to implement
+	 * our loopback functionality
 	 */
 	for (i = 0; i < loop->qlen && result == 0; i++) {
-		req = lb_alloc_ep_req(ep, 0);
-		if (!req)
-			goto fail1;
+		result = -ENOMEM;
+
+		in_req = usb_ep_alloc_request(loop->in_ep, GFP_KERNEL);
+		if (!in_req)
+			goto fail;
+
+		out_req = lb_alloc_ep_req(loop->out_ep, 0);
+		if (!out_req)
+			goto fail_in;
+
+		in_req->complete = loopback_complete;
+		out_req->complete = loopback_complete;
+
+		in_req->buf = out_req->buf;
+		/* length will be set in complete routine */
+		in_req->context = out_req;
+		out_req->context = in_req;
 
-		req->complete = loopback_complete;
-		result = usb_ep_queue(ep, req, GFP_ATOMIC);
+		result = usb_ep_queue(loop->out_ep, out_req, GFP_ATOMIC);
 		if (result) {
 			ERROR(cdev, "%s queue req --> %d\n",
-					ep->name, result);
-			goto fail1;
+					loop->out_ep->name, result);
+			goto fail_out;
 		}
 	}
 
 	return 0;
 
-fail1:
-	usb_ep_disable(ep);
+fail_out:
+	free_ep_req(loop->out_ep, out_req);
+fail_in:
+	usb_ep_free_request(loop->in_ep, in_req);
+fail:
+	return result;
+}
+
+static int enable_endpoint(struct usb_composite_dev *cdev,
+			   struct f_loopback *loop, struct usb_ep *ep)
+{
+	int					result;
+
+	result = config_ep_by_speed(cdev->gadget, &(loop->function), ep);
+	if (result)
+		goto out;
 
-fail0:
+	result = usb_ep_enable(ep);
+	if (result < 0)
+		goto out;
+	ep->driver_data = loop;
+	result = 0;
+
+out:
 	return result;
 }
 
@@ -347,13 +389,24 @@ enable_loopback(struct usb_composite_dev *cdev, struct f_loopback *loop)
 
 	result = enable_endpoint(cdev, loop, loop->in_ep);
 	if (result)
-		return result;
+		goto out;
 
 	result = enable_endpoint(cdev, loop, loop->out_ep);
 	if (result)
-		return result;
+		goto disable_in;
+
+	result = alloc_requests(cdev, loop);
+	if (result)
+		goto disable_out;
 
 	DBG(cdev, "%s enabled\n", loop->function.name);
+	return 0;
+
+disable_out:
+	usb_ep_disable(loop->out_ep);
+disable_in:
+	usb_ep_disable(loop->in_ep);
+out:
 	return result;
 }
 
-- 
2.6.1