linux-kernel - [PATCH] timekeeping: Adjust the leap state for the correct auxiliary timekeeper

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Message-Id: <20260120-timekeeper-auxclock-leapstate-v1-1-5b358c6b3cfd@linutronix.de>
Date: Tue, 20 Jan 2026 07:55:55 +0100
From: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
To: John Stultz <jstultz@...gle.com>, Thomas Gleixner <tglx@...utronix.de>, 
 Stephen Boyd <sboyd@...nel.org>
Cc: linux-kernel@...r.kernel.org, stable@...r.kernel.org, 
 Thomas Weißschuh <thomas.weissschuh@...utronix.de>
Subject: [PATCH] timekeeping: Adjust the leap state for the correct
 auxiliary timekeeper

When __do_ajdtimex() was introduced to handle adjtimex for any
timekeeper, this reference to tk_core was not updated. When called on an
auxiliary timekeeper, the core timekeeper would be updated incorrectly.

This gets caught by the lock debugging diagnostics because the
timekeepers sequence lock gets written to without holding its
associated spinlock:

WARNING: include/linux/seqlock.h:226 at __do_adjtimex+0x394/0x3b0, CPU#2: test/125
aux_clock_adj (kernel/time/timekeeping.c:2979)
__do_sys_clock_adjtime (kernel/time/posix-timers.c:1161 kernel/time/posix-timers.c:1173)
do_syscall_64 (arch/x86/entry/syscall_64.c:63 (discriminator 1) arch/x86/entry/syscall_64.c:94 (discriminator 1))
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:131)

Update the correct auxiliary timekeeper.

Fixes: 775f71ebedd3 ("timekeeping: Make do_adjtimex() reusable")
Fixes: ecf3e7030491 ("timekeeping: Provide adjtimex() for auxiliary clocks")
Cc: stable@...r.kernel.org
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
---
 kernel/time/timekeeping.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 3ec3daa4acab..91fa2003351c 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -2735,7 +2735,7 @@ static int __do_adjtimex(struct tk_data *tkd, struct __kernel_timex *txc,
 		timekeeping_update_from_shadow(tkd, TK_CLOCK_WAS_SET);
 		result->clock_set = true;
 	} else {
-		tk_update_leap_state_all(&tk_core);
+		tk_update_leap_state_all(tkd);
 	}
 
 	/* Update the multiplier immediately if frequency was set directly */

---
base-commit: 3db5306b0bd562ac0fe7eddad26c60ebb6f5fdd4
change-id: 20260119-timekeeper-auxclock-leapstate-a087229c80e8

Best regards,
-- 
Thomas Weißschuh <thomas.weissschuh@...utronix.de>