patch "usb: gadget: u_ether: remove interrupt throttling" added to usb-linus

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

usb: gadget: u_ether: remove interrupt throttling

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, 1 Nov 2016 13:20:22 +0200
Subject: usb: gadget: u_ether: remove interrupt throttling
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According to Dave Miller "the networking stack has a hard requirement that all SKBs which are transmitted must have their completion signalled in a fininte amount of time. This is because, until the SKB is freed by the driver, it holds onto socket, netfilter, and other subsystem resources."

In summary, this means that using TX IRQ throttling for the networking gadgets is, at least, complex and we should avoid it for the time being.

---
 drivers/usb/gadget/function/u_ether.c | 8 --------
 1 file changed, 8 deletions(-)

index fe1811650dbc..5d1bd13a56c1 100644
@@ -588,14 +588,6 @@ static netdev_tx_t eth_start_xmit(struct sk_buff *skb,
 
 	req->length = length;
 
-	/* 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)) &&
-					!list_empty(&dev->tx_reqs))
-			? ((atomic_read(&dev->tx_qlen) % dev->qmult) != 0)
-			: 0;
-
 	retval = usb_ep_queue(in, req, GFP_ATOMIC);
 	switch (retval) {
 	default:

2.10.2