[patch] usbnet: fix 100% CPU use on suspended device

[patch] usbnet: fix 100% CPU use on suspended device

[Elly Jones]

From: Elly Jones <ellyjones@google.com>

This patch causes the usbnet module not to attempt to submit URBs to the device
if the device is not ready to accept them. This fixes a misbehavior trigged by
the Qualcomm Gobi driver (released under GPL through their Code Aurora
initiative) which causes the usbnet core to consume 100% of CPU attempting and
failing to submit URBs. This patch is against Linus's 2.6 repo commit
a9f7f2e74ae0e6a801a2433dc8e9124d73da0cb4.
Signed-off-by: Elizabeth Jones <ellyjones@google.com>
---
diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index 81c76ad..df7e72e 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -1172,6 +1172,7 @@ static void usbnet_bh (unsigned long param)
 	// or are we maybe short a few urbs?
 	} else if (netif_running (dev->net) &&
 		   netif_device_present (dev->net) &&
+		   dev->udev->can_submit &&
 		   !timer_pending (&dev->delay) &&
 		   !test_bit (EVENT_RX_HALT, &dev->flags)) {
 		int	temp = dev->rxq.qlen;

Re: [patch] usbnet: fix 100% CPU use on suspended device

[David Brownell]

> This patch causes the usbnet module not to 
> attempt to submit URBs to the device
> if the device is not ready to accept them.

Looks plausible to me; can't test it or review
the underlying bug though.

> This fixes a
> misbehavior trigged by
> the Qualcomm Gobi driver (released under GPL through their Code Aurora initiative)

Which appears to be short on testing... :(

- Dave