On Wed, 12 Oct 2011, Oliver Neukum wrote:
> looking at the usbhid code it seems to me that there is no protection
> between the error handling code and pre_reset() racing.
>
> In particular there seems to be no protection from hid_retry_timeout() calling
> hid_start_in() which would start IO after hid_pre_reset() has already called
> hid_cease_io() because that uses del_timer(), not del_timer_sync()
>
> What do you think about this patch?
Looks like you made a good catch, thanks. Out of curiosity -- did you
encounter this happening for real, or have you find out by code reading?
>
> Regards
> Oliver
>
> From d13b3b42669cfbed3716d040cc8ce489fecd6963 Mon Sep 17 00:00:00 2001
> From: Oliver Neukum <oliver@xxxxxxxxxx>
> Date: Wed, 12 Oct 2011 10:54:54 +0200
> Subject: [PATCH] USB: usbhid: cancel timer for retry synchronously
>
> This makes sure IO is never restarted while a reset is going on
>
> Signed-off-by: Oliver Neukum <oneukum@xxxxxxx>
> ---
> drivers/hid/usbhid/hid-core.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
> index ad978f5..77e705c 100644
> --- a/drivers/hid/usbhid/hid-core.c
> +++ b/drivers/hid/usbhid/hid-core.c
> @@ -1270,7 +1270,7 @@ static void hid_cancel_delayed_stuff(struct usbhid_device *usbhid)
>
> static void hid_cease_io(struct usbhid_device *usbhid)
> {
> - del_timer(&usbhid->io_retry);
> + del_timer_sync(&usbhid->io_retry);
> usb_kill_urb(usbhid->urbin);
> usb_kill_urb(usbhid->urbctrl);
> usb_kill_urb(usbhid->urbout);
Will queue this up. Thanks again,
--
Jiri Kosina
SUSE Labs
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