user/sven/linux.git/kernel/cpu.c, branch v4.11.8

cpu/hotplug: Drop the device lock on error

2017-06-14T13:07:50Z

commit 40da1b11f01e43aad1aa6cea64681b6125e8a2a7 upstream. If a custom CPU target is specified and that one is not available _or_ can't be interrupted then the code returns to userland without dropping a lock as notices by lockdep: |echo 133 > /sys/devices/system/cpu/cpu7/hotplug/target | ================================================ | [ BUG: lock held when returning to user space! ] | ------------------------------------------------ | bash/503 is leaving the kernel with locks still held! | 1 lock held by bash/503: | #0: (device_hotplug_lock){+.+...}, at: [] lock_device_hotplug_sysfs+0x10/0x40 So release the lock then. Fixes: 757c989b9994 ("cpu/hotplug: Make target state writeable") Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Link: http://lkml.kernel.org/r/20170602142714.3ogo25f2wbq6fjpj@linutronix.de Signed-off-by: Greg Kroah-Hartman

cpu/hotplug: Serialize callback invocations proper

2017-03-14T18:19:27Z

The setup/remove_state/instance() functions in the hotplug core code are serialized against concurrent CPU hotplug, but unfortunately not serialized against themself. As a consequence a concurrent invocation of these function results in corruption of the callback machinery because two instances try to invoke callbacks on remote cpus at the same time. This results in missing callback invocations and initiator threads waiting forever on the completion. The obvious solution to replace get_cpu_online() with cpu_hotplug_begin() is not possible because at least one callsite calls into these functions from a get_online_cpu() locked region. Extend the protection scope of the cpuhp_state_mutex from solely protecting the state arrays to cover the callback invocation machinery as well. Fixes: 5b7aa87e0482 ("cpu/hotplug: Implement setup/removal interface") Reported-and-tested-by: Bart Van Assche Signed-off-by: Sebastian Andrzej Siewior Cc: hpa@zytor.com Cc: mingo@kernel.org Cc: akpm@linux-foundation.org Cc: torvalds@linux-foundation.org Link: http://lkml.kernel.org/r/20170314150645.g4tdyoszlcbajmna@linutronix.de Signed-off-by: Thomas Gleixner

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:35Z

We are going to split out of , which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder file that just maps to to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:35Z

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:29Z

cpu/hotplug: Remove unused but set variable in _cpu_down()

2017-01-18T10:55:09Z

After the recent removal of the hotplug notifiers the variable 'hasdied' in _cpu_down() is set but no longer read, leading to the following GCC warning when building with 'make W=1': kernel/cpu.c:767:7: warning: variable ‘hasdied’ set but not used [-Wunused-but-set-variable] Fix it by removing the variable. Fixes: 530e9b76ae8f ("cpu/hotplug: Remove obsolete cpu hotplug register/unregister functions") Signed-off-by: Tobias Klauser Cc: Peter Zijlstra Cc: Sebastian Andrzej Siewior Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20170117143501.20893-1-tklauser@distanz.ch Signed-off-by: Thomas Gleixner

cpu/hotplug: Provide dynamic range for prepare stage

2017-01-16T12:20:05Z

Mathieu reported that the LTTNG modules are broken as of 4.10-rc1 due to the removal of the cpu hotplug notifiers. Usually I don't care much about out of tree modules, but LTTNG is widely used in distros. There are two ways to solve that: 1) Reserve a hotplug state for LTTNG 2) Add a dynamic range for the prepare states. While #1 is the simplest solution, #2 is the proper one as we can convert in tree users, which do not care about ordering, to the dynamic range as well. Add a dynamic range which allows LTTNG to request states in the prepare stage. Reported-and-tested-by: Mathieu Desnoyers Signed-off-by: Thomas Gleixner Reviewed-by: Mathieu Desnoyers Cc: Peter Zijlstra Cc: Sebastian Sewior Cc: Steven Rostedt Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1701101353010.3401@nanos Signed-off-by: Thomas Gleixner

smp/hotplug: Undo tglxs brainfart

2016-12-27T01:30:24Z

The attempt to prevent overwriting an active state resulted in a disaster which effectively disables all dynamically allocated hotplug states. Cleanup the mess. Fixes: dc280d936239 ("cpu/hotplug: Prevent overwriting of callbacks") Reported-by: Markus Trippelsdorf Reported-by: Boris Ostrovsky Signed-off-by: Thomas Gleixner Signed-off-by: Linus Torvalds

cpu/hotplug: Remove obsolete cpu hotplug register/unregister functions

2016-12-25T09:47:43Z

hotcpu_notifier(), cpu_notifier(), __hotcpu_notifier(), __cpu_notifier(), register_hotcpu_notifier(), register_cpu_notifier(), __register_hotcpu_notifier(), __register_cpu_notifier(), unregister_hotcpu_notifier(), unregister_cpu_notifier(), __unregister_hotcpu_notifier(), __unregister_cpu_notifier() are unused now. Remove them and all related code. Remove also the now pointless cpu notifier error injection mechanism. The states can be executed step by step and error rollback is the same as cpu down, so any state transition can be tested w/o requiring the notifier error injection. Some CPU hotplug states are kept as they are (ab)used for hotplug state tracking. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Cc: Peter Zijlstra Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20161221192112.005642358@linutronix.de Signed-off-by: Thomas Gleixner

cpu/hotplug: Prevent overwriting of callbacks

2016-12-25T09:47:42Z

Developers manage to overwrite states blindly without thought. That's fatal and hard to debug. Add sanity checks to make it fail. This requries to restructure the code so that the dynamic state allocation happens in the same lock protected section as the actual store. Otherwise the previous assignment of 'Reserved' to the name field would trigger the overwrite check. Signed-off-by: Thomas Gleixner Cc: Peter Zijlstra Cc: Sebastian Siewior Link: http://lkml.kernel.org/r/20161221192111.675234535@linutronix.de Signed-off-by: Thomas Gleixner