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author | Mauro Carvalho Chehab <mchehab+samsung@kernel.org> | 2018-12-07 08:03:16 -0500 |
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committer | Mauro Carvalho Chehab <mchehab+samsung@kernel.org> | 2018-12-07 08:39:52 -0500 |
commit | e4d7b113fdccde1acf8638c5879f2a450d492303 (patch) | |
tree | 799a8a456750099c1cbb08323688453e87e3f39f | |
parent | 9ed5d5fb8b432badc967decf97e4294cbb216eef (diff) | |
download | linux-e4d7b113fdccde1acf8638c5879f2a450d492303.tar.bz2 |
media: cedrus: don't initialize pointers with zero
A common mistake is to assume that initializing a var with:
struct foo f = { 0 };
Would initialize a zeroed struct. Actually, what this does is
to initialize the first element of the struct to zero.
According to C99 Standard 6.7.8.21:
"If there are fewer initializers in a brace-enclosed
list than there are elements or members of an aggregate,
or fewer characters in a string literal used to initialize
an array of known size than there are elements in the array,
the remainder of the aggregate shall be initialized implicitly
the same as objects that have static storage duration."
So, in practice, it could zero the entire struct, but, if the
first element is not an integer, it will produce warnings:
drivers/staging/media/sunxi/cedrus/cedrus.c:drivers/staging/media/sunxi/cedrus/cedrus.c:78:49: warning: Using plain integer as NULL pointer
drivers/staging/media/sunxi/cedrus/cedrus_dec.c:drivers/staging/media/sunxi/cedrus/cedrus_dec.c:29:35: warning: Using plain integer as NULL pointer
As the right initialization would be, instead:
struct foo f = { NULL };
Another way to initialize it with gcc is to use:
struct foo f = {};
That seems to be a gcc extension, but clang also does the right thing,
and that's a clean way for doing it.
Anyway, I decided to check upstream what's the most commonly pattern.
The "= {}" pattern has about 2000 entries:
$ git grep -E "=\s*\{\s*\}"|wc -l
1951
The standard-C compliant pattern has about 2500 entries:
$ git grep -E "=\s*\{\s*NULL\s*\}"|wc -l
137
$ git grep -E "=\s*\{\s*0\s*\}"|wc -l
2323
Meaning that developers have split options on that.
So, let's opt to the simpler form.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
-rw-r--r-- | drivers/staging/media/sunxi/cedrus/cedrus.c | 2 | ||||
-rw-r--r-- | drivers/staging/media/sunxi/cedrus/cedrus_dec.c | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/drivers/staging/media/sunxi/cedrus/cedrus.c b/drivers/staging/media/sunxi/cedrus/cedrus.c index 4711df7ee5a3..ff11cbeba205 100644 --- a/drivers/staging/media/sunxi/cedrus/cedrus.c +++ b/drivers/staging/media/sunxi/cedrus/cedrus.c @@ -76,7 +76,7 @@ static int cedrus_init_ctrls(struct cedrus_dev *dev, struct cedrus_ctx *ctx) return -ENOMEM; for (i = 0; i < CEDRUS_CONTROLS_COUNT; i++) { - struct v4l2_ctrl_config cfg = { 0 }; + struct v4l2_ctrl_config cfg = {}; cfg.elem_size = cedrus_controls[i].elem_size; cfg.id = cedrus_controls[i].id; diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_dec.c b/drivers/staging/media/sunxi/cedrus/cedrus_dec.c index 6c5e310a7cf7..591d191d4286 100644 --- a/drivers/staging/media/sunxi/cedrus/cedrus_dec.c +++ b/drivers/staging/media/sunxi/cedrus/cedrus_dec.c @@ -26,7 +26,7 @@ void cedrus_device_run(void *priv) { struct cedrus_ctx *ctx = priv; struct cedrus_dev *dev = ctx->dev; - struct cedrus_run run = { 0 }; + struct cedrus_run run = {}; struct media_request *src_req; run.src = v4l2_m2m_next_src_buf(ctx->fh.m2m_ctx); |