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

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

[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 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 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

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.

Cc: <stable@vger.kernel.org>
Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
---
 drivers/usb/gadget/function/u_ether.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/function/u_ether.c b/drivers/usb/gadget/function/u_ether.c
index 9c8c9ed1dc9e..fe1811650dbc 100644
--- a/drivers/usb/gadget/function/u_ether.c
+++ b/drivers/usb/gadget/function/u_ether.c
@@ -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