user/sven/linux.git/include/linux/hrtimer.h, branch v6.14.6

hrtimers: Handle CPU state correctly on hotplug

2025-01-16T12:06:14Z

Consider a scenario where a CPU transitions from CPUHP_ONLINE to halfway through a CPU hotunplug down to CPUHP_HRTIMERS_PREPARE, and then back to CPUHP_ONLINE: Since hrtimers_prepare_cpu() does not run, cpu_base.hres_active remains set to 1 throughout. However, during a CPU unplug operation, the tick and the clockevents are shut down at CPUHP_AP_TICK_DYING. On return to the online state, for instance CFS incorrectly assumes that the hrtick is already active, and the chance of the clockevent device to transition to oneshot mode is also lost forever for the CPU, unless it goes back to a lower state than CPUHP_HRTIMERS_PREPARE once. This round-trip reveals another issue; cpu_base.online is not set to 1 after the transition, which appears as a WARN_ON_ONCE in enqueue_hrtimer(). Aside of that, the bulk of the per CPU state is not reset either, which means there are dangling pointers in the worst case. Address this by adding a corresponding startup() callback, which resets the stale per CPU state and sets the online flag. [ tglx: Make the new callback unconditionally available, remove the online modification in the prepare() callback and clear the remaining state in the starting callback instead of the prepare callback ] Fixes: 5c0930ccaad5 ("hrtimers: Push pending hrtimers away from outgoing CPU earlier") Signed-off-by: Koichiro Den Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/20241220134421.3809834-1-koichiro.den@canonical.com

hrtimers: Delete hrtimer_init_on_stack()

2024-11-07T01:47:07Z

hrtimer_init_on_stack() is now unused. Delete it. Signed-off-by: Nam Cao Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/510ce0d2944c4a382ea51e51d03dcfb73ba0f4f7.1730386209.git.namcao@linutronix.de

hrtimers: Delete hrtimer_init_sleeper_on_stack()

2024-11-07T01:47:06Z

hrtimer_init_sleeper_on_stack() is now unused. Delete it. Signed-off-by: Nam Cao Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/52549846635c0b3a2abf82101f539efdabcd9778.1730386209.git.namcao@linutronix.de

hrtimers: Introduce hrtimer_update_function()

2024-11-07T01:47:05Z

Some users of hrtimer need to change the callback function after the initial setup. They write to hrtimer::function directly. That's not safe under all circumstances as the write is lockless and a concurrent timer expiry might end up using the wrong function pointer. Introduce hrtimer_update_function(), which also performs runtime checks whether it is safe to modify the callback. This allows to make hrtimer::function private once all users are converted. Signed-off-by: Nam Cao Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/20a937b0ae09ad54b5b6d86eabead7c570f1b72e.1730386209.git.namcao@linutronix.de

hrtimers: Introduce hrtimer_setup_sleeper_on_stack()

2024-11-07T01:47:05Z

The hrtimer_init*() API is replaced by hrtimer_setup*() variants to initialize the timer including the callback function at once. hrtimer_init_sleeper_on_stack() does not need user to setup the callback function separately, so a new variant would not be strictly necessary. Nonetheless, to keep the naming convention consistent, introduce hrtimer_setup_sleeper_on_stack(). hrtimer_init_on_stack() will be removed once all users are converted. Signed-off-by: Nam Cao Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/7b5e18e6dd0ace9eaa211201528cb9dc23752454.1730386209.git.namcao@linutronix.de

hrtimers: Introduce hrtimer_setup_on_stack()

2024-11-07T01:47:05Z

To initialize hrtimer on stack, hrtimer_init_on_stack() needs to be called and also hrtimer::function must be set. This is error-prone and awkward to use. Introduce hrtimer_setup_on_stack() which does both of these things, so that users of hrtimer can be simplified. The new setup function also has a sanity check for the provided function pointer. If NULL, a warning is emitted and a dummy callback installed. hrtimer_init_on_stack() will be removed as soon as all of its users have been converted to the new function. Signed-off-by: Nam Cao Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/4b05e2ab3a82c517adf67fabc0f0cd8fe118b97c.1730386209.git.namcao@linutronix.de

hrtimers: Introduce hrtimer_setup() to replace hrtimer_init()

2024-11-07T01:47:05Z

To initialize hrtimer, hrtimer_init() needs to be called and also hrtimer::function must be set. This is error-prone and awkward to use. Introduce hrtimer_setup() which does both of these things, so that users of hrtimer can be simplified. The new setup function also has a sanity check for the provided function pointer. If NULL, a warning is emitted and a dummy callback installed. hrtimer_init() will be removed as soon as all of its users have been converted to the new function. Signed-off-by: Nam Cao Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/5057c1ddbfd4b92033cd93d37fe38e6b069d5ba6.1730386209.git.namcao@linutronix.de

hrtimers: Add missing hrtimer_init() trace points

2024-11-07T01:47:04Z

hrtimer_init*_on_stack() is not covered by tracing when CONFIG_DEBUG_OBJECTS_TIMERS=y. Rework the functions similar to hrtimer_init() and hrtimer_init_sleeper() so that the hrtimer_init() tracepoint is unconditionally available. The rework makes hrtimer_init_sleeper() unused. Delete it. Signed-off-by: Nam Cao Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/74528e8abf2bb96e8bee85ffacbf14e15cf89f0d.1730386209.git.namcao@linutronix.de

hrtimers: Update formatting of documentation

2024-02-19T08:37:59Z

Documentation of functions lacks the annotations which are used by kernel-doc and *.rst to make appearance in rendered documents more user-friendly. Use those annotations to improve user-friendliness. While at it prevent duplication of comments and use a reference instead. Signed-off-by: Anna-Maria Behnsen Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20240123164702.55612-3-anna-maria@linutronix.de

hrtimers: Move hrtimer base related definitions into hrtimer_defs.h

2024-02-19T08:37:59Z

hrtimer base related struct definitions are part of hrtimers.h as it is required there. With this, also the struct documentation which is for core code internal use, is exposed into the general api. To prevent this, move all core internal definitions and the related includes into hrtimer_defs.h. Signed-off-by: Anna-Maria Behnsen Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20240123164702.55612-2-anna-maria@linutronix.de