patch "usb: gadget: function: u_ether: don't starve tx request queue" added to usb-linus

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 my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus 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 hopefully also be merged in Linus's tree for the next -rc kernel release.

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

From: Felipe Balbi <[email protected]>
Date: Tue, 4 Oct 2016 15:14:43 +0300
Subject: usb: gadget: function: u_ether: don't starve tx request queue
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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.

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

index 9c8c9ed1dc9e..fe1811650dbc 100644
@@ -590,8 +590,9 @@ static netdev_tx_t eth_start_xmit(struct sk_buff *skb,
 
 	/* 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;
 

2.10.0