On Fri, Aug 11 2017, Jerry Zhang wrote:
> Users can apply i/o in the wrong direction on an
> endpoint to stall it. In case there is an error
> that does not allow the endpoint to be stalled,
> we want the user to know.
>
> An operation to stall the endpoint will return
> EBADMSG if successful, EAGAIN if there are still
> queued requests, and other errors depending on
> the underlying implementation.
>
> Also remove the conditional since it is always true.
I’m not sure it’s true. ‘ep = epfile->ep;’ is executed prior to taking
a spin_lock so by the time the spin_lock is taken, epfile->ep could
change.
> Signed-off-by: Jerry Zhang <zhangje...@google.com>
> ---
> Notes for v1:
> - What's the reasoning behind having this behavior
> in epfile_io? We could also consider moving this
> codepath to an ioctl and documenting it.
This was a design in gadgetfs. At this point I don’t think it can be
changed.
> drivers/usb/gadget/function/f_fs.c | 7 +++----
> 1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/usb/gadget/function/f_fs.c
> b/drivers/usb/gadget/function/f_fs.c
> index d21874b35cf6..9990944a7245 100644
> --- a/drivers/usb/gadget/function/f_fs.c
> +++ b/drivers/usb/gadget/function/f_fs.c
> @@ -961,10 +961,9 @@ static ssize_t ffs_epfile_io(struct file *file, struct
> ffs_io_data *io_data)
> /* In the meantime, endpoint got disabled or changed. */
> ret = -ESHUTDOWN;
> } else if (halt) {
> - /* Halt */
> - if (likely(epfile->ep == ep) && !WARN_ON(!ep->ep))
> - usb_ep_set_halt(ep->ep);
> - ret = -EBADMSG;
> + ret = usb_ep_set_halt(ep->ep);
> + if (!ret)
> + ret = -EBADMSG;
> } else if (unlikely(data_len == -EINVAL)) {
> /*
> * Sanity Check: even though data_len can't be used
--
Best regards
ミハウ “𝓶𝓲𝓷𝓪86” ナザレヴイツ
«If at first you don’t succeed, give up skydiving»
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