linux-kernel - [PATCHv5.1 4/5] check quirk to pad epout buf size when not aligned to maxpacketsize

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Date:	Tue, 12 Nov 2013 00:58:55 +0100
From:	Michal Nazarewicz <mina86@...a86.com>
To:	David Cohen <david.a.cohen@...ux.intel.com>, balbi@...com,
	gregkh@...uxfoundation.org
Cc:	stern@...land.harvard.edu, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCHv5.1 4/5] check quirk to pad epout buf size when not aligned to
 maxpacketsize

Check gadget.quirk_ep_out_aligned_size to decide if buffer size requires
to be aligned to maxpacketsize of an out endpoint.  ffs_epfile_io() needs
to pad epout buffer to match above condition if quirk is found.

Signed-off-by: Michal Nazarewicz <mina86@...a86.com>
---
 drivers/usb/gadget/f_fs.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

On Tue, Nov 12 2013, David Cohen wrote:
> One curiosity here. This patch prints the following warning:
>
> In file included from (...)/drivers/usb/gadget/g_ffs.c:55:0:
> (...)/drivers/usb/gadget/f_fs.c: In function 'ffs_epfile_io.isra.18':
> (...)/drivers/usb/gadget/f_fs.c:837:15: warning: 'data_len' may be used 
> uninitialized in this function [-Wmaybe-uninitialized]

With the below code, this should no longer be a problem.

Also fixes issues pointed out by Alan.

diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
index 6cb0b22..9aa3200 100644
--- a/drivers/usb/gadget/f_fs.c
+++ b/drivers/usb/gadget/f_fs.c
@@ -753,6 +753,7 @@ static ssize_t ffs_epfile_io(struct file *file,
 			     char __user *buf, size_t len, int read)
 {
 	struct ffs_epfile *epfile = file->private_data;
+	struct usb_gadget *gadget = epfile->ffs->gadget;
 	struct ffs_ep *ep;
 	char *data = NULL;
 	ssize_t ret;
@@ -788,7 +789,14 @@ static ssize_t ffs_epfile_io(struct file *file,
 
 	/* Allocate & copy */
 	if (!halt) {
-		data = kmalloc(len, GFP_KERNEL);
+		/*
+		 * Controller requires buffer size to be aligned to
+		 * maxpacketsize of an out endpoint.
+		 */
+		size_t data_len = read && gadget->quirk_ep_out_aligned_size ?
+			usb_ep_align_maxpacketsize(ep->ep, len) : len;
+
+		data = kmalloc(data_len, GFP_KERNEL);
 		if (unlikely(!data))
 			return -ENOMEM;
 
-- 
1.8.4.1

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