[RFC PATCH v4 03/11] lib: vdso: only read hrtimer_res when needed in __cvdso_clock_getres()

[Christophe Leroy]

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

Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
---
 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 9563be3cb5fa..8b3084d9a3ec 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -326,7 +326,6 @@ 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;
 
@@ -338,7 +337,6 @@ int __cvdso_clock_getres_common(clockid_t clock, struct 
__kernel_timespec *res)
            vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
                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
         * clocks are handled in the VDSO directly.
@@ -348,7 +346,7 @@ 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().
-- 
2.13.3