tree 4420dbfac9ba213e1604320cf9615a505ca909fd
parent 786083667e0ced85ce17c4c0b6c57a9f47c5b9f2
author Oleg Nesterov <oleg@tv-sign.ru> 1209456027 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> 1209481571 -0700

workqueues: shrink cpu_populated_map when CPU dies

When cpu_populated_map was introduced, it was supposed that cwq->thread can
survive after CPU_DEAD, that is why we never shrink cpu_populated_map.

This is not very nice, we can safely remove the already dead CPU from the map.
 The only required change is that destroy_workqueue() must hold the hotplug
lock until it destroys all cwq->thread's, to protect the cpu_populated_map.
We could make the local copy of cpu mask and drop the lock, but
sizeof(cpumask_t) may be very large.

Also, fix the comment near queue_work().  Unless _cpu_down() happens we do
guarantee the cpu-affinity of the work_struct, and we have users which rely on
this.

[akpm@linux-foundation.org: repair comment]
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>