Messages in this thread Patch in this message | | | Date | Sun, 09 Sep 2012 23:42:08 +0100 | From | Ben Hutchings <> | Subject | [ 18/95] usb: gadget: u_ether: fix kworker 100% CPU issue with still used interfaces in eth_stop |
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3.2-stable review patch. If anyone has any objections, please let me know.
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From: Michael Grzeschik <m.grzeschik@pengutronix.de>
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 <tlinder@codeaurora.org> Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- drivers/usb/gadget/u_ether.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/drivers/usb/gadget/u_ether.c b/drivers/usb/gadget/u_ether.c index 90e82e2..0e52309 100644 --- 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 *net) 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 *net) * 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); }
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