Re: [PATCH 7/8] ACPI: property: Skip MIPI property table without "mipi-img" prefix

Sakari Ailus
2023-01-20T11:59:14Z

On Thu, Jan 19, 2023 at 06:09:25PM +0200, Andy Shevchenko wrote:
> On Thu, Jan 19, 2023 at 03:51:33PM +0000, Sakari Ailus wrote:
> > On Tue, Jan 17, 2023 at 05:29:54PM +0200, Andy Shevchenko wrote:
> > > On Tue, Jan 17, 2023 at 02:22:43PM +0200, Sakari Ailus wrote:
>
> ...
>
> > > > + if (memcmp(elements[0].string.pointer, MIPI_IMG_PREFIX,
> > > > + sizeof(MIPI_IMG_PREFIX) - 1))
> > >
> > > str_has_prefix()
> >
> > str_has_prefix() calls strlen() on prefix on every call. sizeof() will
> > generate much less code --- it's just a number.
>
> Have you tried that? Because the strlen() over const string literals will be
> optimized away on compilation time.

Actually not. There seem to be an implementation of strlen() in
include/linux/fortify-string.h that would seem to be capable of doing that.
However its use is conditional to kernel configuration.

--
Sakari Ailus