Patch "usb: gadget: function: u_ether: don't starve tx request queue" has been added to the 4.4-stable tree

Patch "usb: gadget: function: u_ether: don't starve tx request queue" has been added to the 4.4-stable tree

[gregkh]

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

    usb: gadget: function: u_ether: don't starve tx request queue

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     usb-gadget-function-u_ether-don-t-starve-tx-request-queue.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 6c83f77278f17a7679001027e9231291c20f0d8a Mon Sep 17 00:00:00 2001
From: Felipe Balbi <felipe.balbi@linux.intel.com>
Date: Tue, 4 Oct 2016 15:14:43 +0300
Subject: usb: gadget: function: u_ether: don't starve tx request queue
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Felipe Balbi <felipe.balbi@linux.intel.com>

commit 6c83f77278f17a7679001027e9231291c20f0d8a upstream.

If we don't guarantee that we will always get an
interrupt at least when we're queueing our very last
request, we could fall into situation where we queue
every request with 'no_interrupt' set. This will
cause the link to get stuck.

The behavior above has been triggered with g_ether
and dwc3.

Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/usb/gadget/function/u_ether.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/usb/gadget/function/u_ether.c
+++ b/drivers/usb/gadget/function/u_ether.c
@@ -596,8 +596,9 @@ static netdev_tx_t eth_start_xmit(struct
 
 	/* throttle high/super speed IRQ rate back slightly */
 	if (gadget_is_dualspeed(dev->gadget))
-		req->no_interrupt = (dev->gadget->speed == USB_SPEED_HIGH ||
-				     dev->gadget->speed == USB_SPEED_SUPER)
+		req->no_interrupt = (((dev->gadget->speed == USB_SPEED_HIGH ||
+				       dev->gadget->speed == USB_SPEED_SUPER)) &&
+					!list_empty(&dev->tx_reqs))
 			? ((atomic_read(&dev->tx_qlen) % dev->qmult) != 0)
 			: 0;
 


Patches currently in stable-queue which might be from felipe.balbi@linux.intel.com are

queue-4.4/usb-gadget-function-u_ether-don-t-starve-tx-request-queue.patch