linux-kernel - [PATCH 3/5] [media] cx231xx: constify videobuf_queue

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Date:   Fri,  4 Aug 2017 14:09:46 +0200
From:   Julia Lawall <Julia.Lawall@...6.fr>
To:     Mauro Carvalho Chehab <mchehab@...nel.org>
Cc:     bhumirks@...il.com, kernel-janitors@...r.kernel.org,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 3/5] [media] cx231xx: constify videobuf_queue_ops structures

These videobuf_queue_ops structures are only passed as the second
argument to videobuf_queue_vmalloc_init, which is declared as const.
Thus the videobuf_queue_ops structures themselves can be const.

Done with the help of Coccinelle.

// <smpl>
@r disable optional_qualifier@
identifier i;
position p;
@@
static struct videobuf_queue_ops i@p = { ... };

@ok1@
identifier r.i;
expression e1;
position p;
@@
videobuf_queue_vmalloc_init(e1,&i@p,...)

@bad@
position p != {r.p,ok1.p};
identifier r.i;
struct videobuf_queue_ops e;
@@
e@i@p

@depends on !bad disable optional_qualifier@
identifier r.i;
@@
static
+const
 struct videobuf_queue_ops i = { ... };
// </smpl>

In the first case, there is a second commented call to
videobuf_queue_sg_init with the structure as the second argument.  If that
code will be uncommented, the const will remain correct, because the second
parameter of that function is also const.

Signed-off-by: Julia Lawall <Julia.Lawall@...6.fr>

---
 drivers/media/usb/cx231xx/cx231xx-417.c   |    2 +-
 drivers/media/usb/cx231xx/cx231xx-video.c |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/media/usb/cx231xx/cx231xx-417.c b/drivers/media/usb/cx231xx/cx231xx-417.c
index 8d5eb99..d538fa4 100644
--- a/drivers/media/usb/cx231xx/cx231xx-417.c
+++ b/drivers/media/usb/cx231xx/cx231xx-417.c
@@ -1490,7 +1490,7 @@ static void bb_buf_release(struct videobuf_queue *q,
 	free_buffer(q, buf);
 }
 
-static struct videobuf_queue_ops cx231xx_qops = {
+static const struct videobuf_queue_ops cx231xx_qops = {
 	.buf_setup    = bb_buf_setup,
 	.buf_prepare  = bb_buf_prepare,
 	.buf_queue    = bb_buf_queue,
diff --git a/drivers/media/usb/cx231xx/cx231xx-video.c b/drivers/media/usb/cx231xx/cx231xx-video.c
index f67f868..179b848 100644
--- a/drivers/media/usb/cx231xx/cx231xx-video.c
+++ b/drivers/media/usb/cx231xx/cx231xx-video.c
@@ -859,7 +859,7 @@ static void buffer_release(struct videobuf_queue *vq,
 	free_buffer(vq, buf);
 }
 
-static struct videobuf_queue_ops cx231xx_video_qops = {
+static const struct videobuf_queue_ops cx231xx_video_qops = {
 	.buf_setup = buffer_setup,
 	.buf_prepare = buffer_prepare,
 	.buf_queue = buffer_queue,