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Subject[RFC PATCH v3 05/12] lib: vdso: Avoid duplication in __cvdso_clock_getres()
Date
VDSO_HRES and VDSO_RAW clocks are handled the same way.

Don't duplicate code.

Before the patch:
clock-getres-monotonic-raw: vdso: 737 nsec/call
clock-getres-monotonic-coarse: vdso: 753 nsec/call
clock-getres-monotonic: vdso: 691 nsec/call

After the patch:
clock-getres-monotonic-raw: vdso: 715 nsec/call
clock-getres-monotonic-coarse: vdso: 715 nsec/call
clock-getres-monotonic: vdso: 714 nsec/call

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
---
lib/vdso/gettimeofday.c | 11 ++---------
1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index d75e44ba716f..decd3f2b37af 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -184,7 +184,6 @@ static __maybe_unused
int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *res)
{
const struct vdso_data *vd = __arch_get_vdso_data();
- u64 hrtimer_res;
u32 msk;
u64 ns;

@@ -192,27 +191,21 @@ int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *res)
if (unlikely((u32) clock >= MAX_CLOCKS))
return -1;

- hrtimer_res = READ_ONCE(vd[CS_HRES_COARSE].hrtimer_res);
/*
* Convert the clockid to a bitmask and use it to check which
* clocks are handled in the VDSO directly.
*/
msk = 1U << clock;
- if (msk & VDSO_HRES) {
+ if (msk & (VDSO_HRES | VDSO_RAW)) {
/*
* Preserves the behaviour of posix_get_hrtimer_res().
*/
- ns = hrtimer_res;
+ ns = READ_ONCE(vd[CS_HRES_COARSE].hrtimer_res);
} else if (msk & VDSO_COARSE) {
/*
* Preserves the behaviour of posix_get_coarse_res().
*/
ns = LOW_RES_NSEC;
- } else if (msk & VDSO_RAW) {
- /*
- * Preserves the behaviour of posix_get_hrtimer_res().
- */
- ns = hrtimer_res;
} else {
return -1;
}
--
2.13.3
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