This is a note to let you know that I've just added the patch titled
usb: gadget: u_ether: fix kworker 100% CPU issue with still used interfaces
in eth_stop
to the 3.4-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-u_ether-fix-kworker-100-cpu-issue-with-still-used-interfaces-in-eth_stop.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From b1b552a69b8805e7e338074a9e8b670b4a795218 Mon Sep 17 00:00:00 2001
From: Michael Grzeschik <[email protected]>
Date: Wed, 8 Aug 2012 11:48:10 +0200
Subject: usb: gadget: u_ether: fix kworker 100% CPU issue with still used
interfaces in eth_stop
From: Michael Grzeschik <[email protected]>
commit b1b552a69b8805e7e338074a9e8b670b4a795218 upstream.
This patch fixes an issue introduced by patch:
72c973d usb: gadget: add usb_endpoint_descriptor to struct usb_ep
Without this patch we see a kworker taking 100% CPU, after this sequence:
- Connect gadget to a windows host
- load g_ether
- ifconfig up <ip>; ifconfig down; ifconfig up
- ping <windows host>
The "ifconfig down" results in calling eth_stop(), which will call
usb_ep_disable() and, if the carrier is still ok, usb_ep_enable():
usb_ep_disable(link->in_ep);
usb_ep_disable(link->out_ep);
if (netif_carrier_ok(net)) {
usb_ep_enable(link->in_ep);
usb_ep_enable(link->out_ep);
}
The ep should stay enabled, but will not, as ep_disable set the desc
pointer to NULL, therefore the subsequent ep_enable will fail. This leads
to permanent rescheduling of the eth_work() worker as usb_ep_queue()
(called by the worker) will fail due to the unconfigured endpoint.
We fix this issue by saving the ep descriptors and re-assign them before
usb_ep_enable().
Cc: Tatyana Brokhman <[email protected]>
Signed-off-by: Michael Grzeschik <[email protected]>
Signed-off-by: Marc Kleine-Budde <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/usb/gadget/u_ether.c | 6 ++++++
1 file changed, 6 insertions(+)
--- a/drivers/usb/gadget/u_ether.c
+++ b/drivers/usb/gadget/u_ether.c
@@ -669,6 +669,8 @@ static int eth_stop(struct net_device *n
spin_lock_irqsave(&dev->lock, flags);
if (dev->port_usb) {
struct gether *link = dev->port_usb;
+ const struct usb_endpoint_descriptor *in;
+ const struct usb_endpoint_descriptor *out;
if (link->close)
link->close(link);
@@ -682,10 +684,14 @@ static int eth_stop(struct net_device *n
* their own pace; the network stack can handle old packets.
* For the moment we leave this here, since it works.
*/
+ in = link->in_ep->desc;
+ out = link->out_ep->desc;
usb_ep_disable(link->in_ep);
usb_ep_disable(link->out_ep);
if (netif_carrier_ok(net)) {
DBG(dev, "host still using in/out endpoints\n");
+ link->in_ep->desc = in;
+ link->out_ep->desc = out;
usb_ep_enable(link->in_ep);
usb_ep_enable(link->out_ep);
}
Patches currently in stable-queue which might be from
[email protected] are
queue-3.4/usb-gadget-u_ether-fix-kworker-100-cpu-issue-with-still-used-interfaces-in-eth_stop.patch
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