On Wed, 2013-11-13 at 09:11 +0800, wangbiao wrote:
Hi,
> 2, for the same reason,dev->wait should be judged again before use it,
> as between the judge point(if(dev->wait)) and use point(wakeup(dev->wait)),
> the dev->wait may be set NULL by another cpu.
>
> for issue 1, declare unlink_wakeup in global section instead of on stack.
> for issue 2, use a temporary local var to keep the value of dev->wait
> in stack and judge it before using.
>
> Signed-off-by: wang, biao <biao.wang@xxxxxxxxx>
> Acked-by: Ingo Molnar <mingo.kernel.org@xxxxxxxxx>
> Acked-by: Oliver Neukum <oneukum@xxxxxxx>
Well, I didn't exactly ack this version. I requested a change
to the last version, which you did, but you did also other things.
> Acked-by: Zhang, Di <di.zhang@xxxxxxxxx>
> ---
> drivers/net/usb/usbnet.c | 6 ++++--
> 1 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
> index 90a429b..0603ef6 100644
> --- a/drivers/net/usb/usbnet.c
> +++ b/drivers/net/usb/usbnet.c
> @@ -86,6 +86,7 @@ static const char driver_name [] = "usbnet";
>
> /* use ethtool to change the level for any given device */
> static int msg_level = -1;
> +static DECLARE_WAIT_QUEUE_HEAD(unlink_wakeup);
> module_param (msg_level, int, 0);
> MODULE_PARM_DESC (msg_level, "Override default message level");
>
> @@ -761,7 +762,6 @@ EXPORT_SYMBOL_GPL(usbnet_unlink_rx_urbs);
> // precondition: never called in_interrupt
> static void usbnet_terminate_urbs(struct usbnet *dev)
> {
> - DECLARE_WAIT_QUEUE_HEAD_ONSTACK(unlink_wakeup);
> DECLARE_WAITQUEUE(wait, current);
> int temp;
That solves the first problem.
> @@ -1449,7 +1449,9 @@ static void usbnet_bh (unsigned long param)
> // waiting for all pending urbs to complete?
> if (dev->wait) {
> if ((dev->txq.qlen + dev->rxq.qlen + dev->done.qlen) == 0) {
> - wake_up (dev->wait);
> + wait_queue_head_t *wait_d = dev->wait;
> + if (wait_d)
Here's the window. Either it can be freed or not. Moving the check
won't help.
> + wake_up(wait_d);
> }
>
> // or are we maybe short a few urbs?
Regards
Oliver
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