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authorThomas Gleixner <tglx@linutronix.de>2024-10-09 10:29:08 +0200
committerThomas Gleixner <tglx@linutronix.de>2024-10-25 19:49:14 +0200
commit97e53792538dd8993172e231f09dadee57f66d69 (patch)
tree8f1d2946e6410b11f86791252eb72ef3fefb3d1f
parent6b1ef640f4c48663777972ab0953a3eb6355ef85 (diff)
downloadlwn-97e53792538dd8993172e231f09dadee57f66d69.tar.gz
lwn-97e53792538dd8993172e231f09dadee57f66d69.zip
timekeeping: Provide timekeeping_restore_shadow()
Functions which operate on the real timekeeper, e.g. do_settimeofday(), have error conditions. If they are hit a full timekeeping update is still required because the already committed operations modified the timekeeper. When switching these functions to operate on the shadow timekeeper then the full update can be avoided in the error case, but the modified shadow timekeeper has to be restored. Provide a helper function for that. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/all/20241009-devel-anna-maria-b4-timers-ptp-timekeeping-v2-15-554456a44a15@linutronix.de
-rw-r--r--kernel/time/timekeeping.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index c30b1870fc58..ed0e328fedd0 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -774,6 +774,15 @@ static inline void tk_update_ktime_data(struct timekeeper *tk)
tk->tkr_raw.base = ns_to_ktime(tk->raw_sec * NSEC_PER_SEC);
}
+/*
+ * Restore the shadow timekeeper from the real timekeeper.
+ */
+static void timekeeping_restore_shadow(struct tk_data *tkd)
+{
+ lockdep_assert_held(&tkd->lock);
+ memcpy(&tkd->shadow_timekeeper, &tkd->timekeeper, sizeof(tkd->timekeeper));
+}
+
static void timekeeping_update(struct tk_data *tkd, struct timekeeper *tk, unsigned int action)
{
lockdep_assert_held(&tkd->lock);
@@ -801,7 +810,7 @@ static void timekeeping_update(struct tk_data *tkd, struct timekeeper *tk, unsig
* timekeeper structure on the next update with stale data
*/
if (action & TK_MIRROR)
- memcpy(&tkd->shadow_timekeeper, tk, sizeof(*tk));
+ timekeeping_restore_shadow(tkd);
}
static void timekeeping_update_from_shadow(struct tk_data *tkd, unsigned int action)