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SubjectRe: [patch 1/5] lib/vdso/32: Remove inconsistent NULL pointer checks
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On 7/28/19 2:12 PM, Thomas Gleixner wrote:
> The 32bit variants of vdso_clock_gettime()/getres() have a NULL pointer
> check for the timespec pointer. That's inconsistent vs. 64bit.
>
> But the vdso implementation will never be consistent versus the syscall
> because the only case which it can handle is NULL. Any other invalid
> pointer will cause a segfault. So special casing NULL is not really useful.
>
> Remove it along with the superflouos syscall fallback invocation as that
> will return -EFAULT anyway. That also gets rid of the dubious typecast
> which only works because the pointer is NULL.

Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>

>
> Fixes: 00b26474c2f1 ("lib/vdso: Provide generic VDSO implementation")
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
> lib/vdso/gettimeofday.c | 18 ++----------------
> 1 file changed, 2 insertions(+), 16 deletions(-)
>
> --- a/lib/vdso/gettimeofday.c
> +++ b/lib/vdso/gettimeofday.c
> @@ -115,9 +115,6 @@ static __maybe_unused int
> struct __kernel_timespec ts;
> int ret;
>
> - if (res == NULL)
> - goto fallback;
> -
> ret = __cvdso_clock_gettime(clock, &ts);
>
> if (ret == 0) {
> @@ -126,9 +123,6 @@ static __maybe_unused int
> }
>
> return ret;
> -
> -fallback:
> - return clock_gettime_fallback(clock, (struct __kernel_timespec *)res);
> }
>
> static __maybe_unused int
> @@ -204,10 +198,8 @@ int __cvdso_clock_getres(clockid_t clock
> goto fallback;
> }
>
> - if (res) {
> - res->tv_sec = 0;
> - res->tv_nsec = ns;
> - }
> + res->tv_sec = 0;
> + res->tv_nsec = ns;
>
> return 0;
>
> @@ -221,9 +213,6 @@ static __maybe_unused int
> struct __kernel_timespec ts;
> int ret;
>
> - if (res == NULL)
> - goto fallback;
> -
> ret = __cvdso_clock_getres(clock, &ts);
>
> if (ret == 0) {
> @@ -232,8 +221,5 @@ static __maybe_unused int
> }
>
> return ret;
> -
> -fallback:
> - return clock_getres_fallback(clock, (struct __kernel_timespec *)res);
> }
> #endif /* VDSO_HAS_CLOCK_GETRES */
>
>

--
Regards,
Vincenzo

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