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lib/vdso: Only read hrtimer_res when needed in __cvdso_clock_getres() 

Only perform READ_ONCE(vd[CS_HRES_COARSE].hrtimer_res) for
HRES and RAW clocks.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/7ac2f0d21652f95e2bbdfa6bd514ae6c7caf53ab.1579196675.git.christophe.leroy@c-s.fr
This commit is contained in:
Christophe Leroy 2020-01-16 17:58:27 +00:00 committed by Thomas Gleixner
parent 99570c3da9
commit 49a101d716
1 changed files with 1 additions and 3 deletions
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4
lib/vdso/gettimeofday.c
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@ -312,7 +312,6 @@ static __maybe_unused
int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *res) int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *res)
{ {
const struct vdso_data *vd = __arch_get_vdso_data(); const struct vdso_data *vd = __arch_get_vdso_data();
u64 hrtimer_res;
u32 msk; u32 msk;
u64 ns; u64 ns;
@ -323,7 +322,6 @@ int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *res)
if (IS_ENABLED(CONFIG_TIME_NS) && vd->clock_mode == VCLOCK_TIMENS) if (IS_ENABLED(CONFIG_TIME_NS) && vd->clock_mode == VCLOCK_TIMENS)
vd = __arch_get_timens_vdso_data(); vd = __arch_get_timens_vdso_data();
hrtimer_res = READ_ONCE(vd[CS_HRES_COARSE].hrtimer_res);
/* /*
* Convert the clockid to a bitmask and use it to check which * Convert the clockid to a bitmask and use it to check which
* clocks are handled in the VDSO directly. * clocks are handled in the VDSO directly.
@ -333,7 +331,7 @@ int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *res)
/* /*
* Preserves the behaviour of posix_get_hrtimer_res(). * 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) { } else if (msk & VDSO_COARSE) {
/* /*
* Preserves the behaviour of posix_get_coarse_res(). * Preserves the behaviour of posix_get_coarse_res().