Sorry, I find some tabs are still missed even I sent out as plain txt by
outlook. Please ignore this again, I will try to resolve this before submit it.
----------------------------------------
> From: unicorn_w...@outlook.com
> To: linux-usb@vger.kernel.org
> CC: oneu...@suse.de; gre...@linuxfoundation.org; unicorn_w...@outlook.com
> Subject: [PATCH]USB: usb-skeleton: add retry for nonblocking read
> Date: Thu, 18 Jul 2013 13:09:20 +0000
>
> From: Chen Wang unicorn_w...@outlook.com
>
> Updated skel_read() in usb-skeleton.c. When there is no data in the buffer,
> we would allow retry for both blocking and nonblocking cases. Original logic
> gives retry only for blocking case. Actually we can also allow retry for
> nonblocking case. This will reuse the existing retry logic and handle the
> return of -EAGAIN in one place. Also if the data to be read is short and can
> be retrieved in quick time, we can also give a chance for nonblocking case
> and may catch the data and copy it back to userspace in one read() call too.
>
> Signed-off-by: Chen Wang unicorn_w...@outlook.com
> ---
> --- linux-3.11-rc1/drivers/usb/usb-skeleton.c.orig 2013-07-18
> 19:35:23.559780152 +0800
> +++ linux-3.11-rc1/drivers/usb/usb-skeleton.c 2013-07-18 19:38:11.546779516
> +0800
> @@ -325,9 +325,8 @@ retry:
> rv = skel_do_read_io(dev, count);
> if (rv < 0)
> goto exit;
> - else if (!(file->f_flags & O_NONBLOCK))
> + else
> goto retry;
> - rv = -EAGAIN;
> }
> exit:
> mutex_unlock(&dev->io_mutex);
