The literals "big-endian" and "little-endian" may be potentially
occurred in other places. Dropping space allows compiler to
"compress" them by using only a single copy.
Cc: Sakari Ailus <[email protected]>
Signed-off-by: Andy Shevchenko <[email protected]>
---
Depends on the
https://lore.kernel.org/lkml/[email protected]/T/#u
but not to be critical or fix-like.
lib/vsprintf.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index b02f01366acb..5818856d5626 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1780,7 +1780,8 @@ char *fourcc_string(char *buf, char *end, const u32 *fourcc,
*p++ = isascii(c) && isprint(c) ? c : '.';
}
- strcpy(p, orig & BIT(31) ? " big-endian" : " little-endian");
+ *p++ = ' ';
+ strcpy(p, orig & BIT(31) ? "big-endian" : "little-endian");
p += strlen(p);
*p++ = ' ';
--
2.34.1
On Mon, Jan 10, 2022 at 10:55:58PM +0200, Andy Shevchenko wrote:
> The literals "big-endian" and "little-endian" may be potentially
> occurred in other places. Dropping space allows compiler to
> "compress" them by using only a single copy.
>
> Cc: Sakari Ailus <[email protected]>
> Signed-off-by: Andy Shevchenko <[email protected]>
Acked-by: Sakari Ailus <[email protected]>
--
Sakari Ailus
On 10/01/2022 21.55, Andy Shevchenko wrote:
> The literals "big-endian" and "little-endian" may be potentially
> occurred in other places. Dropping space allows compiler to
> "compress" them by using only a single copy.
Nit: it's not the compiler which does that, but the linker.
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index b02f01366acb..5818856d5626 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -1780,7 +1780,8 @@ char *fourcc_string(char *buf, char *end, const u32 *fourcc,
> *p++ = isascii(c) && isprint(c) ? c : '.';
> }
>
> - strcpy(p, orig & BIT(31) ? " big-endian" : " little-endian");
> + *p++ = ' ';
> + strcpy(p, orig & BIT(31) ? "big-endian" : "little-endian");
> p += strlen(p);
Hm, ok, those two strings do occur a lot with of_property_read_bool()
and friends. But if you're micro-optimizing anyway, why not drop the
strlen() and say p = stpcpy(...) instead?
Rasmus
On Tue, Jan 11, 2022 at 11:26:21AM +0100, Rasmus Villemoes wrote:
> On 10/01/2022 21.55, Andy Shevchenko wrote:
> > The literals "big-endian" and "little-endian" may be potentially
> > occurred in other places. Dropping space allows compiler to
> > "compress" them by using only a single copy.
>
> Nit: it's not the compiler which does that, but the linker.
Ah, I stand corrected, thanks!
> > - strcpy(p, orig & BIT(31) ? " big-endian" : " little-endian");
> > + *p++ = ' ';
> > + strcpy(p, orig & BIT(31) ? "big-endian" : "little-endian");
> > p += strlen(p);
>
> Hm, ok, those two strings do occur a lot with of_property_read_bool()
> and friends. But if you're micro-optimizing anyway, why not drop the
> strlen() and say p = stpcpy(...) instead?
Why not? I'll do it for v2.
Any thoughts / comments on the
https://lore.kernel.org/lkml/[email protected]/T/#u?
I'm asking since dependency and I would like to know if we still want that
fix or not.
--
With Best Regards,
Andy Shevchenko
On Tue 2022-01-11 13:28:21, Andy Shevchenko wrote:
> On Tue, Jan 11, 2022 at 11:26:21AM +0100, Rasmus Villemoes wrote:
> > On 10/01/2022 21.55, Andy Shevchenko wrote:
> > > The literals "big-endian" and "little-endian" may be potentially
> > > occurred in other places. Dropping space allows compiler to
> > > "compress" them by using only a single copy.
> >
> > Nit: it's not the compiler which does that, but the linker.
>
> Ah, I stand corrected, thanks!
>
> > > - strcpy(p, orig & BIT(31) ? " big-endian" : " little-endian");
> > > + *p++ = ' ';
> > > + strcpy(p, orig & BIT(31) ? "big-endian" : "little-endian");
> > > p += strlen(p);
> >
> > Hm, ok, those two strings do occur a lot with of_property_read_bool()
> > and friends. But if you're micro-optimizing anyway, why not drop the
> > strlen() and say p = stpcpy(...) instead?
>
> Why not? I'll do it for v2.
It is safe here. I just hope that it will not trigger reports from
some tools looking for potential security issues ;-)
> Any thoughts / comments on the
> https://lore.kernel.org/lkml/[email protected]/T/#u?
> I'm asking since dependency and I would like to know if we still want that
> fix or not.
Just commented there. It looks fine to me.
Best Regards,
Petr
On 11/01/2022 16.10, Petr Mladek wrote:
> On Tue 2022-01-11 13:28:21, Andy Shevchenko wrote:
>>>> - strcpy(p, orig & BIT(31) ? " big-endian" : " little-endian");
>>>> + *p++ = ' ';
>>>> + strcpy(p, orig & BIT(31) ? "big-endian" : "little-endian");
>>>> p += strlen(p);
>>>
>>> Hm, ok, those two strings do occur a lot with of_property_read_bool()
>>> and friends. But if you're micro-optimizing anyway, why not drop the
>>> strlen() and say p = stpcpy(...) instead?
>>
>> Why not? I'll do it for v2.
>
> It is safe here. I just hope that it will not trigger reports from
> some tools looking for potential security issues ;-)
>
strcpy() and stpcpy() have exactly the same preconditions and are safe
in exactly the same circumstances, they only differ in their return
value, so I don't see how any tool would warn about a use of (the
only-recently-standardized) stpcpy if it didn't already warn about strcpy.
Rasmus