linux/kernel/cpu.c, branch v2.6.24

CPU HOTPLUG: avoid hotadd when proper possible_map isn't specified

2007-10-19T18:53:44Z

cpu-hot-add should be fail if cpu is not set in cpu_possible_map. If go ahead, the system will panic soon. Especially, arch which requires additional_cpus= parameter should handle this. Tested on ia64. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Use helpers to obtain task pid in printks

2007-10-19T18:53:43Z

The task_struct->pid member is going to be deprecated, so start using the helpers (task_pid_nr/task_pid_vnr/task_pid_nr_ns) in the kernel. The first thing to start with is the pid, printed to dmesg - in this case we may safely use task_pid_nr(). Besides, printks produce more (much more) than a half of all the explicit pid usage. [akpm@linux-foundation.org: git-drm went and changed lots of stuff] Signed-off-by: Pavel Emelyanov Cc: Dave Airlie Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

cpu hotplug: cpu: deliver CPU_UP_CANCELED only to NOTIFY_OKed callbacks with CPU_UP_PREPARE

2007-10-18T21:37:21Z

The functions in a CPU notifier chain is called with CPU_UP_PREPARE event before making the CPU online. If one of the callback returns NOTIFY_BAD, it stops to deliver CPU_UP_PREPARE event, and CPU online operation is canceled. Then CPU_UP_CANCELED event is delivered to the functions in a CPU notifier chain again. This CPU_UP_CANCELED event is delivered to the functions which have been called with CPU_UP_PREPARE, not delivered to the functions which haven't been called with CPU_UP_PREPARE. The problem that makes existing cpu hotplug error handlings complex is that the CPU_UP_CANCELED event is delivered to the function that has returned NOTIFY_BAD, too. Usually we don't expect to call destructor function against the object that has failed to initialize. It is like: err = register_something(); if (err) { unregister_something(); return err; } So it is natural to deliver CPU_UP_CANCELED event only to the functions that have returned NOTIFY_OK with CPU_UP_PREPARE event and not to call the function that have returned NOTIFY_BAD. This is what this patch is doing. Otherwise, every cpu hotplug notifiler has to track whether notifiler event is failed or not for each cpu. (drivers/base/topology.c is doing this with topology_dev_map) Similary this patch makes same thing with CPU_DOWN_PREPARE and CPU_DOWN_FAILED evnets. Acked-by: Rusty Russell Signed-off-by: Akinobu Mita Cc: Gautham R Shenoy Cc: Oleg Nesterov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

PM: Fix dependencies of CONFIG_SUSPEND and CONFIG_HIBERNATION

2007-08-31T08:42:22Z

Dependencies of CONFIG_SUSPEND and CONFIG_HIBERNATION introduced by commit 296699de6bdc717189a331ab6bbe90e05c94db06 "Introduce CONFIG_SUSPEND for suspend-to-Ram and standby" are incorrect, as they don't cover the facts that (1) not all architectures support suspend and (2) SMP hibernation is only possible on X86 and PPC64 (if CONFIG_PPC64_SWSUSP is set). Signed-off-by: Rafael J. Wysocki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

HOTPLUG: Add CPU_DYING notifier

2007-07-16T09:05:49Z

KVM wants a notification when a cpu is about to die, so it can disable hardware extensions, but at a time when user processes cannot be scheduled on the cpu, so it doesn't try to use virtualization extensions after they have been disabled. This adds a CPU_DYING notification. The notification is called in atomic context on the doomed cpu. Signed-off-by: Avi Kivity

microcode: use suspend-related CPU hotplug notifications

2007-05-09T19:30:56Z

Make the microcode driver use the suspend-related CPU hotplug notifications to handle the CPU hotplug events occuring during system-wide suspend and resume transitions. Remove the global variable suspend_cpu_hotplug previously used for this purpose. Signed-off-by: Rafael J. Wysocki Cc: Gautham R Shenoy Cc: Pavel Machek Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Add suspend-related notifications for CPU hotplug

2007-05-09T19:30:56Z

Since nonboot CPUs are now disabled after tasks and devices have been frozen and the CPU hotplug infrastructure is used for this purpose, we need special CPU hotplug notifications that will help the CPU-hotplug-aware subsystems distinguish normal CPU hotplug events from CPU hotplug events related to a system-wide suspend or resume operation in progress. This patch introduces such notifications and causes them to be used during suspend and resume transitions. It also changes all of the CPU-hotplug-aware subsystems to take these notifications into consideration (for now they are handled in the same way as the corresponding "normal" ones). [oleg@tv-sign.ru: cleanups] Signed-off-by: Rafael J. Wysocki Cc: Gautham R Shenoy Cc: Pavel Machek Signed-off-by: Oleg Nesterov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Remove kthread_bind() call from _cpu_down()

2007-05-09T19:30:53Z

We are anyway kthread_stop()ping other per-cpu kernel threads after move_task_off_dead_cpu(), so we can do it with the stop_machine_run thread as well. I just checked with Vatsa if there was any subtle reason why they had put in the kthread_bind() in cpu.c. Vatsa cannot seem to recollect any and I can't see any. So let us just remove the kthread_bind. Signed-off-by: Gautham R Shenoy Cc: Oleg Nesterov Cc: "Eric W. Biederman" Cc: "Rafael J. Wysocki" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

call cpu_chain with CPU_DOWN_FAILED if CPU_DOWN_PREPARE failed

2007-05-09T19:30:51Z

This makes cpu hotplug symmetrical: if CPU_UP_PREPARE fails we get CPU_UP_CANCELED, so we can undo what ever happened on PREPARE. The same should happen for CPU_DOWN_PREPARE. [akpm@linux-foundation.org: fix for reduce-size-of-task_struct-on-64-bit-machines] Cc: Srivatsa Vaddagiri Cc: Gautham Shenoy Signed-off-by: Heiko Carstens Cc: Oleg Nesterov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Define and use new events,CPU_LOCK_ACQUIRE and CPU_LOCK_RELEASE

2007-05-09T19:30:51Z

This is an attempt to provide an alternate mechanism for postponing a hotplug event instead of using a global mechanism like lock_cpu_hotplug. The proposal is to add two new events namely CPU_LOCK_ACQUIRE and CPU_LOCK_RELEASE. The notification for these two events would be sent out before and after a cpu_hotplug event respectively. During the CPU_LOCK_ACQUIRE event, a cpu-hotplug-aware subsystem is supposed to acquire any per-subsystem hotcpu mutex ( Eg. workqueue_mutex in kernel/workqueue.c ). During the CPU_LOCK_RELEASE release event the cpu-hotplug-aware subsystem is supposed to release the per-subsystem hotcpu mutex. The reasons for defining new events as opposed to reusing the existing events like CPU_UP_PREPARE/CPU_UP_FAILED/CPU_ONLINE for locking/unlocking of per-subsystem hotcpu mutexes are as follow: - CPU_LOCK_ACQUIRE: All hotcpu mutexes are taken before subsystems start handling pre-hotplug events like CPU_UP_PREPARE/CPU_DOWN_PREPARE etc, thus ensuring a clean handling of these events. - CPU_LOCK_RELEASE: The hotcpu mutexes will be released only after all subsystems have handled post-hotplug events like CPU_DOWN_FAILED, CPU_DEAD,CPU_ONLINE etc thereby ensuring that there are no subsequent clashes amongst the interdependent subsystems after a cpu hotplugs. This patch also uses __raw_notifier_call chain in _cpu_up to take care of the dependency between the two consequetive calls to raw_notifier_call_chain. [akpm@linux-foundation.org: fix a bug] Signed-off-by: Gautham R Shenoy Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds