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

[David Miller <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>]

From: Elly Jones <ellyjones-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Date: Wed, 21 Jul 2010 14:51:48 -0400

> Subject: [patch] usbnet: fix 100% CPU use on suspended device
> From: Elly Jones <ellyjones-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
> 
> 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-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>

If the Qualcomm Gobi driver is the only one where this happens, maybe the
real problem is in that driver.

I'm not applying this until a USB person looks more deeply into this.

> ---
> 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;
> --
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