A-Team_Digital_Solutions/android_kernel_motorola_sm6375
Watch
2
0
Fork
You've already forked android_kernel_motorola_sm6375
 0
mirror of https://github.com/BobTheBlinker/android_kernel_motorola_sm6375.git synced 2026-11-09 20:31:13 -05:00
Code Issues Projects Releases Packages Wiki Activity

net/core/flow.c: Fix CPU hotplug callback registration

Browse source 
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 code in net/core/flow.c by using this latter form of callback
registration.

Cc: Li RongQing <[email protected]>
Cc: Sasha Levin <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Chris Metcalf <[email protected]>
Cc: Ingo Molnar <[email protected]>
Acked-by: David S. Miller <[email protected]>
Signed-off-by: Srivatsa S. Bhat <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>
This commit is contained in:
Srivatsa S. Bhat 2014-03-11 02:12:51 +05:30 • committed by Rafael J. Wysocki
commit e30a293e8a
1 changed files with 7 additions and 1 deletions
Download patch file Download diff file Expand all files Collapse all files

8
net/core/flow.c
View file

@ -456,6 +456,8 @@ static int __init flow_cache_init(struct flow_cache *fc)
if (!fc->percpu)
return -ENOMEM;
cpu_notifier_register_begin();
for_each_online_cpu(i) {
if (flow_cache_cpu_prepare(fc, i))
goto err;
@ -463,7 +465,9 @@ static int __init flow_cache_init(struct flow_cache *fc)
fc->hotcpu_notifier = (struct notifier_block){
.notifier_call = flow_cache_cpu,
};
register_hotcpu_notifier(&fc->hotcpu_notifier);
__register_hotcpu_notifier(&fc->hotcpu_notifier);
cpu_notifier_register_done();
setup_timer(&fc->rnd_timer, flow_cache_new_hashrnd,
(unsigned long) fc);
@ -479,6 +483,8 @@ err:
fcp->hash_table = NULL;
}
cpu_notifier_register_done();
free_percpu(fc->percpu);
fc->percpu = NULL;