From 63bc2c97b7d45b773d3ee94594c5f01b2f23101d Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Thu, 16 Jan 2020 17:58:27 +0000 Subject: [PATCH] UPSTREAM: 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 Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/7ac2f0d21652f95e2bbdfa6bd514ae6c7caf53ab.1579196675.git.christophe.leroy@c-s.fr (cherry picked from commit 49a101d7169c7729c7bab6b2f896faae34bd6c3d) Signed-off-by: Mark Salyzyn Bug: 154668398 Change-Id: I0441a793d4703755e8026f23c07e5c1f12544319 --- lib/vdso/gettimeofday.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c index 2bc387500f2d..20f4fb3bfcc8 100644 --- a/lib/vdso/gettimeofday.c +++ b/lib/vdso/gettimeofday.c @@ -186,7 +186,6 @@ 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; @@ -194,7 +193,6 @@ 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. @@ -204,7 +202,7 @@ int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *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) { /* * Preserves the behaviour of posix_get_coarse_res().