From: Mikhail Gavrilov Date: Tue, 16 Jun 2026 07:09:14 +0000 (+0500) Subject: timekeeping: Register default clocksource before taking tk_core.lock X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8fa30821180a9a19e78e9f4df1c0ba710252801e;p=thirdparty%2Flinux.git timekeeping: Register default clocksource before taking tk_core.lock Commit f24df84cbe05 ("time/jiffies: Register jiffies clocksource before usage") moved the jiffies clocksource registration into clocksource_default_clock(), so that it is registered lazily on the first call. __clocksource_register() acquires clocksource_mutex, but the first caller is timekeeping_init(), which invokes clocksource_default_clock() while holding tk_core.lock, a raw spinlock. Acquiring a sleeping mutex while holding a raw spinlock is invalid. The default clocksource only has to be registered before tk_setup_internals() consumes its mult/shift/maxadj. Neither clocksource_default_clock(), the ->enable() callback, nor the registration itself need tk_core.lock, so fetch and enable the clock before acquiring the lock. This preserves the "register before usage" ordering while keeping clocksource_mutex out of the raw spinlock section. clocksource_default_clock() has a second caller, clocksource_done_booting(), which invokes it with clocksource_mutex already held. That path avoids a recursive lock because timekeeping_init() has already run and set cs_jiffies_registered, so the registration is skipped there. This change does not alter that; it only fixes the invalid wait context in timekeeping_init(). Fixes: f24df84cbe05 ("time/jiffies: Register jiffies clocksource before usage") Signed-off-by: Mikhail Gavrilov Signed-off-by: Thomas Gleixner Reported-by: Breno Leitao Reported-by: Oleg Nesterov Reviewed-by: Breno Leitao Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260616070914.65818-1-mikhail.v.gavrilov@gmail.com --- diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 0d5b67f609bbf..b1b5ec43c0f27 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -2061,13 +2061,14 @@ void __init timekeeping_init(void) */ wall_to_mono = timespec64_sub(boot_offset, wall_time); + clock = clocksource_default_clock(); + if (clock->enable) + clock->enable(clock); + guard(raw_spinlock_irqsave)(&tk_core.lock); ntp_init(); - clock = clocksource_default_clock(); - if (clock->enable) - clock->enable(clock); tk_setup_internals(tks, clock); tk_set_xtime(tks, &wall_time);