linux-kernel - Re: [PATCH] usb: ffs: fix regression when quirk_ep_out_aligned

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Date:	Wed, 08 Oct 2014 13:34:16 +0200
From:	Michal Nazarewicz <mina86@...a86.com>
To:	David Cohen <david.a.cohen@...ux.intel.com>, balbi@...com,
	gregkh@...uxfoundation.org
Cc:	r.baldyga@...sung.com, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	David Cohen <david.a.cohen@...ux.intel.com>,
	Qiuxu Zhuo <qiuxu.zhuo@...el.com>
Subject: Re: [PATCH] usb: ffs: fix regression when quirk_ep_out_aligned_size flag is set

On Tue, Oct 07 2014, David Cohen <david.a.cohen@...ux.intel.com> wrote:
> The commit '2e4c7553cd usb: gadget: f_fs: add aio support' broke the
> quirk implemented to align buffer size to maxpacketsize on out endpoint.
> As result, functionfs does not work on Intel platforms using dwc3 driver
> (i.e. Bay Trail and Merrifield). This patch fixes the issue.
>
> This code is based on a previous Qiuxu's patch.
>
> Signed-off-by: David Cohen <david.a.cohen@...ux.intel.com>
> Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@...el.com>

Acked-by: Michal Nazarewicz <mina86@...a86.com>

> ---
>
> Hi,
>
> Since this is a feature that worked in past, this patch is meant for 3.17
> kernel. If/when we pass review and accept it on 3.17, I'll send a version for
> stable 3.16 kernel too. It is not required for 3.14, since the regression came
> later.
>
> Br, David Cohen
>
> ---
>  drivers/usb/gadget/function/f_fs.c | 21 ++++++++++++++++-----
>  1 file changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
> index 0dc3552d1360..6e2b8063b170 100644
> --- a/drivers/usb/gadget/function/f_fs.c
> +++ b/drivers/usb/gadget/function/f_fs.c
> @@ -648,15 +648,26 @@ static void ffs_user_copy_worker(struct work_struct *work)
>  	if (io_data->read && ret > 0) {
>  		int i;
>  		size_t pos = 0;
> +
> +		/*
> +		 * Since req->length may be bigger than io_data->len (after
> +		 * being rounded up to maxpacketsize), we may end up with more
> +		 * data then user space has space for.
> +		 */
> +		ret = min_t(int, ret, io_data->len);
> +
>  		use_mm(io_data->mm);
>  		for (i = 0; i < io_data->nr_segs; i++) {
> +			size_t len = min_t(size_t, ret - pos,
> +					io_data->iovec[i].iov_len);
> +			if (!len)
> +				break;
>  			if (unlikely(copy_to_user(io_data->iovec[i].iov_base,
> -						 &io_data->buf[pos],
> -						 io_data->iovec[i].iov_len))) {
> +						 &io_data->buf[pos], len))) {
>  				ret = -EFAULT;
>  				break;
>  			}
> -			pos += io_data->iovec[i].iov_len;
> +			pos += len;
>  		}
>  		unuse_mm(io_data->mm);
>  	}
> @@ -794,7 +805,7 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
>  				goto error_lock;
>  
>  			req->buf      = data;
> -			req->length   = io_data->len;
> +			req->length   = data_len;
>  
>  			io_data->buf = data;
>  			io_data->ep = ep->ep;
> @@ -816,7 +827,7 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
>  
>  			req = ep->req;
>  			req->buf      = data;
> -			req->length   = io_data->len;
> +			req->length   = data_len;
>  
>  			req->context  = &done;
>  			req->complete = ffs_epfile_io_complete;
> -- 
> 2.1.0
>

-- 
Best regards,                                         _     _
.o. | Liege of Serenely Enlightened Majesty of      o' \,=./ `o
..o | Computer Science,  Michał “mina86” Nazarewicz    (o o)
ooo +--<mpn@...gle.com>--<xmpp:mina86@...ber.org>--ooO--(_)--Ooo--
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