kernel.git/kernel/time, branch linux-5.10.y

hrtimer: Fix trace oddity

2026-03-04T12:19:24Z

[ Upstream commit 5d6446f409da00e5a389125ddb5ce09f5bc404c9 ] It turns out that __run_hrtimer() will trace like: -0 [032] d.h2. 20705.474563: hrtimer_cancel: hrtimer=0xff2db8f77f8226e8 -0 [032] d.h1. 20705.474563: hrtimer_expire_entry: hrtimer=0xff2db8f77f8226e8 now=20699452001850 function=tick_nohz_handler/0x0 Which is a bit nonsensical, the timer doesn't get canceled on expiration. The cause is the use of the incorrect debug helper. Fixes: c6a2a1770245 ("hrtimer: Add tracepoint for hrtimers") Reported-by: Peter Zijlstra (Intel) Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/20260121143208.219595606@infradead.org Signed-off-by: Sasha Levin

ptp: Add PHC file mode checks. Allow RO adjtime() without FMODE_WRITE.

2026-02-06T15:40:03Z

[ Upstream commit b4e53b15c04e3852949003752f48f7a14ae39e86 ] Many devices implement highly accurate clocks, which the kernel manages as PTP Hardware Clocks (PHCs). Userspace applications rely on these clocks to timestamp events, trace workload execution, correlate timescales across devices, and keep various clocks in sync. The kernel’s current implementation of PTP clocks does not enforce file permissions checks for most device operations except for POSIX clock operations, where file mode is verified in the POSIX layer before forwarding the call to the PTP subsystem. Consequently, it is common practice to not give unprivileged userspace applications any access to PTP clocks whatsoever by giving the PTP chardevs 600 permissions. An example of users running into this limitation is documented in [1]. Additionally, POSIX layer requires WRITE permission even for readonly adjtime() calls which are used in PTP layer to return current frequency offset applied to the PHC. Add permission checks for functions that modify the state of a PTP device. Continue enforcing permission checks for POSIX clock operations (settime, adjtime) in the POSIX layer. Only require WRITE access for dynamic clocks adjtime() if any flags are set in the modes field. [1] https://lists.nwtime.org/sympa/arc/linuxptp-users/2024-01/msg00036.html Changes in v4: - Require FMODE_WRITE in ajtime() only for calls modifying the clock in any way. Acked-by: Richard Cochran Reviewed-by: Vadim Fedorenko Signed-off-by: Wojtek Wasko Reviewed-by: Thomas Gleixner Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

posix-clock: Store file pointer in struct posix_clock_context

2026-02-06T15:40:03Z

[ Upstream commit e859d375d1694488015e6804bfeea527a0b25b9f ] File descriptor based pc_clock_*() operations of dynamic posix clocks have access to the file pointer and implement permission checks in the generic code before invoking the relevant dynamic clock callback. Character device operations (open, read, poll, ioctl) do not implement a generic permission control and the dynamic clock callbacks have no access to the file pointer to implement them. Extend struct posix_clock_context with a struct file pointer and initialize it in posix_clock_open(), so that all dynamic clock callbacks can access it. Acked-by: Richard Cochran Reviewed-by: Vadim Fedorenko Reviewed-by: Thomas Gleixner Signed-off-by: Wojtek Wasko Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

Fix memory leak in posix_clock_open()

2026-02-06T15:40:02Z

[ Upstream commit 5b4cdd9c5676559b8a7c944ac5269b914b8c0bb8 ] If the clk ops.open() function returns an error, we don't release the pccontext we allocated for this clock. Re-organize the code slightly to make it all more obvious. Reported-by: Rohit Keshri Acked-by: Oleg Nesterov Fixes: 60c6946675fc ("posix-clock: introduce posix_clock_context concept") Cc: Jakub Kicinski Cc: David S. Miller Cc: Thomas Gleixner Signed-off-by: Linus Torvalds Stable-dep-of: e859d375d169 ("posix-clock: Store file pointer in struct posix_clock_context") Signed-off-by: Sasha Levin

posix-clock: introduce posix_clock_context concept

2026-02-06T15:40:02Z

[ Upstream commit 60c6946675fc06dd2fd2b7a4b6fd1c1f046f1056 ] Add the necessary structure to support custom private-data per posix-clock user. The previous implementation of posix-clock assumed all file open instances need access to the same clock structure on private_data. The need for individual data structures per file open instance has been identified when developing support for multiple timestamp event queue users for ptp_clock. Signed-off-by: Xabier Marquiegui Suggested-by: Richard Cochran Suggested-by: Vinicius Costa Gomes Signed-off-by: David S. Miller Stable-dep-of: e859d375d169 ("posix-clock: Store file pointer in struct posix_clock_context") Signed-off-by: Sasha Levin

clocksource: Fix the CPUs' choice in the watchdog per CPU verification

2025-06-27T10:04:15Z

[ Upstream commit 08d7becc1a6b8c936e25d827becabfe3bff72a36 ] Right now, if the clocksource watchdog detects a clocksource skew, it might perform a per CPU check, for example in the TSC case on x86. In other words: supposing TSC is detected as unstable by the clocksource watchdog running at CPU1, as part of marking TSC unstable the kernel will also run a check of TSC readings on some CPUs to be sure it is synced between them all. But that check happens only on some CPUs, not all of them; this choice is based on the parameter "verify_n_cpus" and in some random cpumask calculation. So, the watchdog runs such per CPU checks on up to "verify_n_cpus" random CPUs among all online CPUs, with the risk of repeating CPUs (that aren't double checked) in the cpumask random calculation. But if "verify_n_cpus" > num_online_cpus(), it should skip the random calculation and just go ahead and check the clocksource sync between all online CPUs, without the risk of skipping some CPUs due to duplicity in the random cpumask calculation. Tests in a 4 CPU laptop with TSC skew detected led to some cases of the per CPU verification skipping some CPU even with verify_n_cpus=8, due to the duplicity on random cpumask generation. Skipping the randomization when the number of online CPUs is smaller than verify_n_cpus, solves that. Suggested-by: Thadeu Lima de Souza Cascardo Signed-off-by: Guilherme G. Piccoli Signed-off-by: Thomas Gleixner Reviewed-by: Paul E. McKenney Link: https://lore.kernel.org/all/20250323173857.372390-1-gpiccoli@igalia.com Signed-off-by: Sasha Levin

posix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del()

2025-06-27T10:04:10Z

commit f90fff1e152dedf52b932240ebbd670d83330eca upstream. If an exiting non-autoreaping task has already passed exit_notify() and calls handle_posix_cpu_timers() from IRQ, it can be reaped by its parent or debugger right after unlock_task_sighand(). If a concurrent posix_cpu_timer_del() runs at that moment, it won't be able to detect timer->it.cpu.firing != 0: cpu_timer_task_rcu() and/or lock_task_sighand() will fail. Add the tsk->exit_state check into run_posix_cpu_timers() to fix this. This fix is not needed if CONFIG_POSIX_CPU_TIMERS_TASK_WORK=y, because exit_task_work() is called before exit_notify(). But the check still makes sense, task_work_add(&tsk->posix_cputimers_work.work) will fail anyway in this case. Cc: stable@vger.kernel.org Reported-by: Benoît Sevens Fixes: 0bdd2ed4138e ("sched: run_posix_cpu_timers: Don't check ->exit_state, use lock_task_sighand()") Signed-off-by: Oleg Nesterov Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

posix-timers: Add cond_resched() to posix_timer_add() search loop

2025-06-04T12:37:00Z

[ Upstream commit 5f2909c6cd13564a07ae692a95457f52295c4f22 ] With a large number of POSIX timers the search for a valid ID might cause a soft lockup on PREEMPT_NONE/VOLUNTARY kernels. Add cond_resched() to the loop to prevent that. [ tglx: Split out from Eric's series ] Signed-off-by: Eric Dumazet Signed-off-by: Thomas Gleixner Reviewed-by: Frederic Weisbecker Link: https://lore.kernel.org/all/20250214135911.2037402-2-edumazet@google.com Link: https://lore.kernel.org/all/20250308155623.635612865@linutronix.de Signed-off-by: Sasha Levin

hrtimers: Mark is_migration_base() with __always_inline

2025-04-10T12:30:49Z

[ Upstream commit 27af31e44949fa85550176520ef7086a0d00fd7b ] When is_migration_base() is unused, it prevents kernel builds with clang, `make W=1` and CONFIG_WERROR=y: kernel/time/hrtimer.c:156:20: error: unused function 'is_migration_base' [-Werror,-Wunused-function] 156 | static inline bool is_migration_base(struct hrtimer_clock_base *base) | ^~~~~~~~~~~~~~~~~ Fix this by marking it with __always_inline. [ tglx: Use __always_inline instead of __maybe_unused and move it into the usage sites conditional ] Signed-off-by: Andy Shevchenko Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/20250116160745.243358-1-andriy.shevchenko@linux.intel.com Signed-off-by: Sasha Levin

clocksource: Use migrate_disable() to avoid calling get_random_u32() in atomic context

2025-03-13T11:47:20Z

[ Upstream commit 6bb05a33337b2c842373857b63de5c9bf1ae2a09 ] The following bug report happened with a PREEMPT_RT kernel: BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 2012, name: kwatchdog preempt_count: 1, expected: 0 RCU nest depth: 0, expected: 0 get_random_u32+0x4f/0x110 clocksource_verify_choose_cpus+0xab/0x1a0 clocksource_verify_percpu.part.0+0x6b/0x330 clocksource_watchdog_kthread+0x193/0x1a0 It is due to the fact that clocksource_verify_choose_cpus() is invoked with preemption disabled. This function invokes get_random_u32() to obtain random numbers for choosing CPUs. The batched_entropy_32 local lock and/or the base_crng.lock spinlock in driver/char/random.c will be acquired during the call. In PREEMPT_RT kernel, they are both sleeping locks and so cannot be acquired in atomic context. Fix this problem by using migrate_disable() to allow smp_processor_id() to be reliably used without introducing atomic context. preempt_disable() is then called after clocksource_verify_choose_cpus() but before the clocksource measurement is being run to avoid introducing unexpected latency. Fixes: 7560c02bdffb ("clocksource: Check per-CPU clock synchronization when marked unstable") Suggested-by: Sebastian Andrzej Siewior Signed-off-by: Waiman Long Signed-off-by: Thomas Gleixner Reviewed-by: Paul E. McKenney Reviewed-by: Sebastian Andrzej Siewior Link: https://lore.kernel.org/all/20250131173323.891943-2-longman@redhat.com Signed-off-by: Sasha Levin