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authorLinus Torvalds <torvalds@linux-foundation.org>2008-01-25 13:42:32 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2008-01-25 13:42:32 -0800
commit0008bf54408d4c0637c24d34642f1038c299be95 (patch)
tree6a14cdacaa3057795381672339737a45e45effc7 /Documentation/cpu-hotplug.txt
parent2d94dfc8c38edf63e91e48fd55c3a8822b6a9ced (diff)
parent6d082592b62689fb91578d0338d04a9f50991990 (diff)
Merge git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched
* git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched: (96 commits) sched: keep total / count stats in addition to the max for sched, futex: detach sched.h and futex.h sched: fix: don't take a mutex from interrupt context sched: print backtrace of running tasks too printk: use ktime_get() softlockup: fix signedness sched: latencytop support sched: fix goto retry in pick_next_task_rt() timers: don't #error on higher HZ values sched: monitor clock underflows in /proc/sched_debug sched: fix rq->clock warps on frequency changes sched: fix, always create kernel threads with normal priority debug: clean up kernel/profile.c sched: remove the !PREEMPT_BKL code sched: make PREEMPT_BKL the default debug: track and print last unloaded module in the oops trace debug: show being-loaded/being-unloaded indicator for modules sched: rt-watchdog: fix .rlim_max = RLIM_INFINITY sched: rt-group: reduce rescheduling hrtimer: unlock hrtimer_wakeup ...
Diffstat (limited to 'Documentation/cpu-hotplug.txt')
-rw-r--r--Documentation/cpu-hotplug.txt11
1 files changed, 6 insertions, 5 deletions
diff --git a/Documentation/cpu-hotplug.txt b/Documentation/cpu-hotplug.txt
index a741f658a3c..fb94f5a71b6 100644
--- a/Documentation/cpu-hotplug.txt
+++ b/Documentation/cpu-hotplug.txt
@@ -109,12 +109,13 @@ Never use anything other than cpumask_t to represent bitmap of CPUs.
for_each_cpu_mask(x,mask) - Iterate over some random collection of cpu mask.
#include <linux/cpu.h>
- lock_cpu_hotplug() and unlock_cpu_hotplug():
+ get_online_cpus() and put_online_cpus():
-The above calls are used to inhibit cpu hotplug operations. While holding the
-cpucontrol mutex, cpu_online_map will not change. If you merely need to avoid
-cpus going away, you could also use preempt_disable() and preempt_enable()
-for those sections. Just remember the critical section cannot call any
+The above calls are used to inhibit cpu hotplug operations. While the
+cpu_hotplug.refcount is non zero, the cpu_online_map will not change.
+If you merely need to avoid cpus going away, you could also use
+preempt_disable() and preempt_enable() for those sections.
+Just remember the critical section cannot call any
function that can sleep or schedule this process away. The preempt_disable()
will work as long as stop_machine_run() is used to take a cpu down.