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authorOleg Nesterov <oleg@tv-sign.ru>2008-07-25 01:47:50 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-25 10:53:40 -0700
commit3da1c84c00c7e5fa8348336bd8c342f9128b0f14 (patch)
treeaf960c65a670319fa86846a493a6d97f9fb37cd9 /kernel/cpu.c
parent8616a89ab761239c963eea3a63be383f127cc7e8 (diff)
downloadlinux-2.6.34-ux500-3da1c84c00c7e5fa8348336bd8c342f9128b0f14.tar.gz
workqueues: make get_online_cpus() useable for work->func()
workqueue_cpu_callback(CPU_DEAD) flushes cwq->thread under cpu_maps_update_begin(). This means that the multithreaded workqueues can't use get_online_cpus() due to the possible deadlock, very bad and very old problem. Introduce the new state, CPU_POST_DEAD, which is called after cpu_hotplug_done() but before cpu_maps_update_done(). Change workqueue_cpu_callback() to use CPU_POST_DEAD instead of CPU_DEAD. This means that create/destroy functions can't rely on get_online_cpus() any longer and should take cpu_add_remove_lock instead. [akpm@linux-foundation.org: fix CONFIG_SMP=n] Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Acked-by: Gautham R Shenoy <ego@in.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Max Krasnyansky <maxk@qualcomm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Paul Menage <menage@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Vegard Nossum <vegard.nossum@gmail.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/cpu.c')
-rw-r--r--kernel/cpu.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 2cc409ce0a8..10ba5f1004a 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -285,6 +285,11 @@ out_allowed:
set_cpus_allowed_ptr(current, &old_allowed);
out_release:
cpu_hotplug_done();
+ if (!err) {
+ if (raw_notifier_call_chain(&cpu_chain, CPU_POST_DEAD | mod,
+ hcpu) == NOTIFY_BAD)
+ BUG();
+ }
return err;
}