From 2424e146bee00ddb4d4f79d3224f54634ca8d2bc Mon Sep 17 00:00:00 2001 From: Nam Cao Date: Tue, 8 Apr 2025 12:38:54 +0200 Subject: hrtimer: Add missing ACCESS_PRIVATE() for hrtimer::function The "function" field of struct hrtimer has been changed to private, but two instances have not been converted to use ACCESS_PRIVATE(). Convert them to use ACCESS_PRIVATE(). Fixes: 04257da0c99c ("hrtimers: Make callback function pointer private") Reported-by: kernel test robot Signed-off-by: Nam Cao Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/20250408103854.1851093-1-namcao@linutronix.de Closes: https://lore.kernel.org/oe-kbuild-all/202504071931.vOVl13tt-lkp@intel.com/ Closes: https://lore.kernel.org/oe-kbuild-all/202504072155.5UAZjYGU-lkp@intel.com/ --- kernel/time/hrtimer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/time') diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index 517ee2590a29..30899a8cc52c 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -366,7 +366,7 @@ static const struct debug_obj_descr hrtimer_debug_descr; static void *hrtimer_debug_hint(void *addr) { - return ((struct hrtimer *) addr)->function; + return ACCESS_PRIVATE((struct hrtimer *)addr, function); } /* -- cgit v1.2.3 From 92e250c624ea37fde64bfd624fd2556f0d846f18 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Fri, 4 Apr 2025 15:34:29 +0200 Subject: timekeeping: Add a lockdep override in tick_freeze() tick_freeze() acquires a raw spinlock (tick_freeze_lock). Later in the callchain (timekeeping_suspend() -> mc146818_avoid_UIP()) the RTC driver acquires a spinlock which becomes a sleeping lock on PREEMPT_RT. Lockdep complains about this lock nesting. Add a lockdep override for this special case and a comment explaining why it is okay. Reported-by: Borislav Petkov Reported-by: Chris Bainbridge Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/all/20250404133429.pnAzf-eF@linutronix.de Closes: https://lore.kernel.org/all/20250330113202.GAZ-krsjAnurOlTcp-@fat_crate.local/ Closes: https://lore.kernel.org/all/CAP-bSRZ0CWyZZsMtx046YV8L28LhY0fson2g4EqcwRAVN1Jk+Q@mail.gmail.com/ --- kernel/time/tick-common.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'kernel/time') diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c index a47bcf71defc..9a3859443c04 100644 --- a/kernel/time/tick-common.c +++ b/kernel/time/tick-common.c @@ -509,6 +509,7 @@ void tick_resume(void) #ifdef CONFIG_SUSPEND static DEFINE_RAW_SPINLOCK(tick_freeze_lock); +static DEFINE_WAIT_OVERRIDE_MAP(tick_freeze_map, LD_WAIT_SLEEP); static unsigned int tick_freeze_depth; /** @@ -528,9 +529,22 @@ void tick_freeze(void) if (tick_freeze_depth == num_online_cpus()) { trace_suspend_resume(TPS("timekeeping_freeze"), smp_processor_id(), true); + /* + * All other CPUs have their interrupts disabled and are + * suspended to idle. Other tasks have been frozen so there + * is no scheduling happening. This means that there is no + * concurrency in the system at this point. Therefore it is + * okay to acquire a sleeping lock on PREEMPT_RT, such as a + * spinlock, because the lock cannot be held by other CPUs + * or threads and acquiring it cannot block. + * + * Inform lockdep about the situation. + */ + lock_map_acquire_try(&tick_freeze_map); system_state = SYSTEM_SUSPEND; sched_clock_suspend(); timekeeping_suspend(); + lock_map_release(&tick_freeze_map); } else { tick_suspend_local(); } @@ -552,8 +566,16 @@ void tick_unfreeze(void) raw_spin_lock(&tick_freeze_lock); if (tick_freeze_depth == num_online_cpus()) { + /* + * Similar to tick_freeze(). On resumption the first CPU may + * acquire uncontended sleeping locks while other CPUs block on + * tick_freeze_lock. + */ + lock_map_acquire_try(&tick_freeze_map); timekeeping_resume(); sched_clock_resume(); + lock_map_release(&tick_freeze_map); + system_state = SYSTEM_RUNNING; trace_suspend_resume(TPS("timekeeping_freeze"), smp_processor_id(), false); -- cgit v1.2.3