| Message ID | 20140310203545.10746.78648.stgit@srivatsabhat.in.ibm.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
diff --git a/arch/s390/kernel/cache.c b/arch/s390/kernel/cache.c index 3a414c0..c0b03c2 100644 --- a/arch/s390/kernel/cache.c +++ b/arch/s390/kernel/cache.c @@ -378,9 +378,12 @@ static int __init cache_init(void) if (!test_facility(34)) return 0; cache_build_info(); + + cpu_notifier_register_begin(); for_each_online_cpu(cpu) cache_add_cpu(cpu); - hotcpu_notifier(cache_hotplug, 0); + __hotcpu_notifier(cache_hotplug, 0); + cpu_notifier_register_done(); return 0; } device_initcall(cache_init);
Subsystems that want to register CPU hotplug callbacks, as well as perform initialization for the CPUs that are already online, often do it as shown below: get_online_cpus(); for_each_online_cpu(cpu) init_cpu(cpu); register_cpu_notifier(&foobar_cpu_notifier); put_online_cpus(); This is wrong, since it is prone to ABBA deadlocks involving the cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently with CPU hotplug operations). Instead, the correct and race-free way of performing the callback registration is: cpu_notifier_register_begin(); for_each_online_cpu(cpu) init_cpu(cpu); /* Note the use of the double underscored version of the API */ __register_cpu_notifier(&foobar_cpu_notifier); cpu_notifier_register_done(); Fix the cacheinfo code in s390 by using this latter form of callback registration. Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: linux-s390@vger.kernel.org Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> --- arch/s390/kernel/cache.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)