summaryrefslogtreecommitdiff
path: root/kernel
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2020-01-27 16:37:40 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2020-01-27 16:37:40 -0800
commita56c41e5d766871231828046f477611d6ee7d2db (patch)
tree411226578e61acba6ddcdd7d440eb225f6ed1a71 /kernel
parentb1dba2473114588be3df916bf629a61bdcc83737 (diff)
parent9f24c540f7f8eb3a981528da9a9a636a5bdf5987 (diff)
Merge tag 'timers-urgent-2020-01-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer fixes from Thomas Gleixner: "Two fixes for the generic VDSO code which missed 5.5: - Make the update to the coarse timekeeper unconditional. This is required because the coarse timekeeper interfaces in the VDSO do not depend on a VDSO capable clocksource. If the system does not have a VDSO capable clocksource and the update is depending on the VDSO capable clocksource, the coarse VDSO interfaces would operate on stale data forever. - Invert the logic of __arch_update_vdso_data() to avoid further head scratching. Tripped over this several times while analyzing the update problem above" * tag 'timers-urgent-2020-01-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: lib/vdso: Update coarse timekeeper unconditionally lib/vdso: Make __arch_update_vdso_data() logic understandable
Diffstat (limited to 'kernel')
-rw-r--r--kernel/time/vsyscall.c37
1 files changed, 17 insertions, 20 deletions
diff --git a/kernel/time/vsyscall.c b/kernel/time/vsyscall.c
index 5ee0f7709410..9577c89179cd 100644
--- a/kernel/time/vsyscall.c
+++ b/kernel/time/vsyscall.c
@@ -28,11 +28,6 @@ static inline void update_vdso_data(struct vdso_data *vdata,
vdata[CS_RAW].mult = tk->tkr_raw.mult;
vdata[CS_RAW].shift = tk->tkr_raw.shift;
- /* CLOCK_REALTIME */
- vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME];
- vdso_ts->sec = tk->xtime_sec;
- vdso_ts->nsec = tk->tkr_mono.xtime_nsec;
-
/* CLOCK_MONOTONIC */
vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC];
vdso_ts->sec = tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
@@ -70,12 +65,6 @@ static inline void update_vdso_data(struct vdso_data *vdata,
vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_TAI];
vdso_ts->sec = tk->xtime_sec + (s64)tk->tai_offset;
vdso_ts->nsec = tk->tkr_mono.xtime_nsec;
-
- /*
- * Read without the seqlock held by clock_getres().
- * Note: No need to have a second copy.
- */
- WRITE_ONCE(vdata[CS_HRES_COARSE].hrtimer_res, hrtimer_resolution);
}
void update_vsyscall(struct timekeeper *tk)
@@ -84,20 +73,17 @@ void update_vsyscall(struct timekeeper *tk)
struct vdso_timestamp *vdso_ts;
u64 nsec;
- if (__arch_update_vdso_data()) {
- /*
- * Some architectures might want to skip the update of the
- * data page.
- */
- return;
- }
-
/* copy vsyscall data */
vdso_write_begin(vdata);
vdata[CS_HRES_COARSE].clock_mode = __arch_get_clock_mode(tk);
vdata[CS_RAW].clock_mode = __arch_get_clock_mode(tk);
+ /* CLOCK_REALTIME also required for time() */
+ vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME];
+ vdso_ts->sec = tk->xtime_sec;
+ vdso_ts->nsec = tk->tkr_mono.xtime_nsec;
+
/* CLOCK_REALTIME_COARSE */
vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME_COARSE];
vdso_ts->sec = tk->xtime_sec;
@@ -110,7 +96,18 @@ void update_vsyscall(struct timekeeper *tk)
nsec = nsec + tk->wall_to_monotonic.tv_nsec;
vdso_ts->sec += __iter_div_u64_rem(nsec, NSEC_PER_SEC, &vdso_ts->nsec);
- update_vdso_data(vdata, tk);
+ /*
+ * Read without the seqlock held by clock_getres().
+ * Note: No need to have a second copy.
+ */
+ WRITE_ONCE(vdata[CS_HRES_COARSE].hrtimer_res, hrtimer_resolution);
+
+ /*
+ * Architectures can opt out of updating the high resolution part
+ * of the VDSO.
+ */
+ if (__arch_update_vdso_data())
+ update_vdso_data(vdata, tk);
__arch_update_vsyscall(vdata, tk);