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author | Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> | 2014-03-11 02:04:45 +0530 |
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committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2014-03-20 13:43:40 +0100 |
commit | eff722b06bdd6de326894ea2353ec0eda3e5ed34 (patch) | |
tree | 32812f5ddeaa7cf23308caaabb0131305ec96346 | |
parent | f0bdb5e0c72b7347c867da539367138ad95c6b24 (diff) | |
download | op-kernel-dev-eff722b06bdd6de326894ea2353ec0eda3e5ed34.zip op-kernel-dev-eff722b06bdd6de326894ea2353ec0eda3e5ed34.tar.gz |
ia64, salinfo: Fix hotplug callback registration
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 salinfo code in ia64 by using this latter form of callback
registration.
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
-rw-r--r-- | arch/ia64/kernel/salinfo.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/arch/ia64/kernel/salinfo.c b/arch/ia64/kernel/salinfo.c index 960a396..ee9719e 100644 --- a/arch/ia64/kernel/salinfo.c +++ b/arch/ia64/kernel/salinfo.c @@ -635,6 +635,8 @@ salinfo_init(void) (void *)salinfo_entries[i].feature); } + cpu_notifier_register_begin(); + for (i = 0; i < ARRAY_SIZE(salinfo_log_name); i++) { data = salinfo_data + i; data->type = i; @@ -669,7 +671,9 @@ salinfo_init(void) salinfo_timer.function = &salinfo_timeout; add_timer(&salinfo_timer); - register_hotcpu_notifier(&salinfo_cpu_notifier); + __register_hotcpu_notifier(&salinfo_cpu_notifier); + + cpu_notifier_register_done(); return 0; } |