linux-kernel - [tip: timers/core] timekeeping: Provide timekeeping_restore

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <172986803133.1442.13788252589194407885.tip-bot2@tip-bot2>
Date: Fri, 25 Oct 2024 14:53:51 -0000
From: "tip-bot2 for Thomas Gleixner" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Thomas Gleixner <tglx@...utronix.de>,
 "Anna-Maria Behnsen" <anna-maria@...utronix.de>,
 John Stultz <jstultz@...gle.com>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: timers/core] timekeeping: Provide timekeeping_restore_shadow()

The following commit has been merged into the timers/core branch of tip:

Commit-ID:     571b39c71a4c23b86e0407684cb6c79f899678bc
Gitweb:        https://git.kernel.org/tip/571b39c71a4c23b86e0407684cb6c79f899678bc
Author:        Thomas Gleixner <tglx@...utronix.de>
AuthorDate:    Wed, 09 Oct 2024 10:29:08 +02:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Fri, 25 Oct 2024 16:41:12 +02:00

timekeeping: Provide timekeeping_restore_shadow()

From: Thomas Gleixner <tglx@...utronix.de>

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@...utronix.de>
Signed-off-by: Anna-Maria Behnsen <anna-maria@...utronix.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Acked-by: John Stultz <jstultz@...gle.com>
Link: https://lore.kernel.org/all/20241009-devel-anna-maria-b4-timers-ptp-timekeeping-v2-15-554456a44a15@linutronix.de

---
 kernel/time/timekeeping.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index c30b187..ed0e328 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)