Tasks can block on hotplug.lock in pin_current_cpu(), but their state might be != RUNNING. So the mutex wakeup will set the state unconditionally to RUNNING. That might cause spurious unexpected wakeups. We could provide a state preserving mutex_lock() function, but this is semantically backwards. So instead we convert the hotplug.lock() to a spinlock for RT, which has the state preserving semantics already. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Cc: Carsten Emde <C.Emde@osadl.org> Cc: John Kacur <jkacur@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Clark Williams <clark.williams@gmail.com> Cc: stable-rt@vger.kernel.org Link: http://lkml.kernel.org/r/1330702617.25686.265.camel@gandalf.stny.rr.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
cpu_unplug_begin() should be called before CPU_DOWN_PREPARE, because at CPU_DOWN_PREPARE cpu_active is cleared and sched_domain is rebuilt. Otherwise the 'sync_unplug' thread will be running on the cpu on which it's created and not bound on the cpu which is about to go down. I found that by an incorrect warning on smp_processor_id() called by sync_unplug/1, and trace shows below: (echo 1 > /sys/device/system/cpu/cpu1/online) bash-1664 [000] 83.136620: _cpu_down: Bind sync_unplug to cpu 1 bash-1664 [000] 83.136623: sched_wait_task: comm=sync_unplug/1 pid=1724 prio=120 bash-1664 [000] 83.136624: _cpu_down: Wake sync_unplug bash-1664 [000] 83.136629: sched_wakeup: comm=sync_unplug/1 pid=1724 prio=120 success=1 target_cpu=000 Wants to be folded back.... Signed-off-by: Yong Zhang <yong.zhang0@gmail.com> Link: http://lkml.kernel.org/r/1318762607-2261-3-git-send-email-yong.zhang0@gmail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
When retry happens, it's likely that the task has been migrated to another cpu (except unplug failed), but it still derefernces the original hotplug_pcp per cpu data. Update the pointer to hotplug_pcp in the retry path, so it points to the current cpu. Signed-off-by: Yong Zhang <yong.zhang0@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20110728031600.GA338@windriver.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Otherwise the output will look a little odd. Signed-off-by: Yong Zhang <yong.zhang0@gmail.com> Link: http://lkml.kernel.org/r/1318762607-2261-2-git-send-email-yong.zhang0@gmail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
get_online_cpus() is a heavy weight function which involves a global mutex. migrate_disable() wants a simpler construct which prevents only a CPU from going doing while a task is in a migrate disabled section. Implement a per cpu lockless mechanism, which serializes only in the real unplug case on a global mutex. That serialization affects only tasks on the cpu which should be brought down. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux: (230 commits)
Revert "tracing: Include module.h in define_trace.h"
irq: don't put module.h into irq.h for tracking irqgen modules.
bluetooth: macroize two small inlines to avoid module.h
ip_vs.h: fix implicit use of module_get/module_put from module.h
nf_conntrack.h: fix up fallout from implicit moduleparam.h presence
include: replace linux/module.h with "struct module" wherever possible
include: convert various register fcns to macros to avoid include chaining
crypto.h: remove unused crypto_tfm_alg_modname() inline
uwb.h: fix implicit use of asm/page.h for PAGE_SIZE
pm_runtime.h: explicitly requires notifier.h
linux/dmaengine.h: fix implicit use of bitmap.h and asm/page.h
miscdevice.h: fix up implicit use of lists and types
stop_machine.h: fix implicit use of smp.h for smp_processor_id
of: fix implicit use of errno.h in include/linux/of.h
of_platform.h: delete needless include <linux/module.h>
acpi: remove module.h include from platform/aclinux.h
miscdevice.h: delete unnecessary inclusion of module.h
device_cgroup.h: delete needless include <linux/module.h>
net: sch_generic remove redundant use of <linux/module.h>
net: inet_timewait_sock doesnt need <linux/module.h>
...
Fix up trivial conflicts (other header files, and removal of the ab3550 mfd driver) in
- drivers/media/dvb/frontends/dibx000_common.c
- drivers/media/video/{mt9m111.c,ov6650.c}
- drivers/mfd/ab3550-core.c
- include/linux/dmaengine.h
The CPU hotplug notifications sent out by the _cpu_up() and _cpu_down() functions depend on the value of the 'tasks_frozen' argument passed to them (which indicates whether tasks have been frozen or not). (Examples for such CPU hotplug notifications: CPU_ONLINE, CPU_ONLINE_FROZEN, CPU_DEAD, CPU_DEAD_FROZEN). Thus, it is essential that while the callbacks for those notifications are running, the state of the system with respect to the tasks being frozen or not remains unchanged, *throughout that duration*. Hence there is a need for synchronizing the CPU hotplug code with the freezer subsystem. Since the freezer is involved only in the Suspend/Hibernate call paths, this patch hooks the CPU hotplug code to the suspend/hibernate notifiers PM_[SUSPEND|HIBERNATE]_PREPARE and PM_POST_[SUSPEND|HIBERNATE] to prevent the race between CPU hotplug and freezer, thus ensuring that CPU hotplug notifications will always be run with the state of the system really being what the notifications indicate, _throughout_ their execution time. Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
The changed files were only including linux/module.h for the EXPORT_SYMBOL infrastructure, and nothing else. Revector them onto the isolated export header for faster compile times. Nothing to see here but a whole lot of instances of: -#include <linux/module.h> +#include <linux/export.h> This commit is only changing the kernel dir; next targets will probably be mm, fs, the arch dirs, etc. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>