On Wed, Feb 19, 2014 at 03:32:12PM -0500, Alan Stern wrote:
> It is an error for a driver to call usb_clear_halt() or
> usb_reset_endpoint() while there are URBs queued for the endpoint,
> because the end result is not well defined. At the time the endpoint
> gets reset, it may or may not be actively running.
>
> As far as I know, no kernel drivers do this. But some userspace
> drivers do, and it seems like a good idea to bring this error to their
> attention.
>
> This patch adds a warning to the kernel log whenever a program invokes
> the USBDEVFS_CLEAR_HALT or USBDEVFS_RESETEP ioctls at an inappropriate
> time, and includes the name of the program. This will make it clear
> that any subsequent errors are not due to the misbehavior of a kernel
> driver.
>
> Signed-off-by: Alan Stern <st...@rowland.harvard.edu>
> Suggested-by: Bjørn Mork <bj...@mork.no>
> CC: Stanislaw Gruszka <sgrus...@redhat.com>
>
> ---
>
>
> [as1741]
>
>
> drivers/usb/core/devio.c | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
> Index: usb-3.14/drivers/usb/core/devio.c
> ===================================================================
> --- usb-3.14.orig/drivers/usb/core/devio.c
> +++ usb-3.14/drivers/usb/core/devio.c
> @@ -1043,6 +1043,20 @@ static int proc_bulk(struct dev_state *p
> return ret;
> }
>
> +static void check_reset_of_active_ep(struct usb_device *udev,
> + unsigned int epnum, char *ioctl_name)
> +{
> + struct usb_host_endpoint **eps;
> + struct usb_host_endpoint *ep;
> +
> + eps = (epnum & USB_DIR_IN) ? udev->ep_in : udev->ep_out;
> + ep = eps[epnum & 0x0f];
> + if (ep && !list_empty(&ep->urb_list))
> + pr_warn("Process %d (%s) called USBDEVFS_%s for active endpoint
> %s ep %02x\n",
> + task_pid_nr(current), current->comm,
> + ioctl_name, dev_name(&udev->dev), epnum);
> +}
If you use dev_warn() here, then userspace has a chance to be able to
map that device name/id to the actual device that was being used at the
time, instead of having to dig through the message itself (tools like
journald already handle dev_* messages like this.)
Care to switch this around?
thanks,
greg k-h
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