Hi Emil,
On 03/08/2018 05:58 AM, Emil Velikov wrote:
Hi Gustavo,
On 7 March 2018 at 19:54, Gustavo A. R. Silva gustavo@embeddedor.com wrote:
In preparation to enabling -Wvla, remove VLA and replace it with a fixed-length array instead. Also, remove variable 'len'.
What is the reason behind adding -Wvla? Is there a thread some that I can read up on?
Sure. This is the thread: https://lkml.org/lkml/2018/3/7/621
Notice that no new IDs have been added in seven years.
Signed-off-by: Gustavo A. R. Silva gustavo@embeddedor.com
drivers/video/fbdev/via/via_aux_vt1632.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/video/fbdev/via/via_aux_vt1632.c b/drivers/video/fbdev/via/via_aux_vt1632.c index d24f4cd..0cd0d2a 100644 --- a/drivers/video/fbdev/via/via_aux_vt1632.c +++ b/drivers/video/fbdev/via/via_aux_vt1632.c @@ -35,10 +35,10 @@ static void probe(struct via_aux_bus *bus, u8 addr) .addr = addr, .name = name}; /* check vendor id and device id */
const u8 id[] = {0x06, 0x11, 0x92, 0x31}, len = ARRAY_SIZE(id);u8 tmp[len];
const u8 id[4] = {0x06, 0x11, 0x92, 0x31};u8 tmp[4];
if (!via_aux_read(&drv, 0x00, tmp, len) || memcmp(id, tmp, len))
if (!via_aux_read(&drv, 0x00, tmp, 4) || memcmp(id, tmp, 4))Generally, hard coding a bunch of numbers like that makes for confusing and fragile code.
You are correct.
A lot simpler and more obvious solution is like the following. It silences the compiler warning (-Wvla - pedantic) you while keeping the original clarity.
const u8 id[] = {0x06, 0x11, 0x92, 0x31}, len = ARRAY_SIZE(id);
u8 tmp[len];
u8 tmp[ARRAY_SIZE(id)]; // Using len causes a Wvla warning
Yeah, this works just fine.
There are a total of four instances of this same issue in other files for the VIA component. I'll fix them and send a single patch shortly.
Thanks for the feedback. I appreciate it. -- Gustavo