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authorSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>2014-03-11 02:09:59 +0530
committerAlex Shi <alex.shi@linaro.org>2015-05-11 20:40:31 +0800
commitcda631acb964bb521add32cd60db08f43a23835c (patch)
treeaee55551dbd2cb8c6d11c8d857b1d11214145b86 /mm
parent30e87174bf64cdce17005dc7fe031ea1aab98161 (diff)
downloadlinux-linaro-stable-cda631acb964bb521add32cd60db08f43a23835c.tar.gz
zsmalloc: Fix CPU 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 zsmalloc code by using this latter form of callback registration. Cc: Nitin Gupta <ngupta@vflare.org> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Acked-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> (cherry picked from commit f0e71fcd0fa6f3f5495cd9ad3f1e4acd94446a55) Signed-off-by: Alex Shi <alex.shi@linaro.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/zsmalloc.c17
1 files changed, 14 insertions, 3 deletions
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 7a8d161b4cd7..b728f10e353b 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -780,21 +780,32 @@ static void zs_exit(void)
{
int cpu;
+ cpu_notifier_register_begin();
+
for_each_online_cpu(cpu)
zs_cpu_notifier(NULL, CPU_DEAD, (void *)(long)cpu);
- unregister_cpu_notifier(&zs_cpu_nb);
+ __unregister_cpu_notifier(&zs_cpu_nb);
+
+ cpu_notifier_register_done();
}
static int zs_init(void)
{
int cpu, ret;
- register_cpu_notifier(&zs_cpu_nb);
+ cpu_notifier_register_begin();
+
+ __register_cpu_notifier(&zs_cpu_nb);
for_each_online_cpu(cpu) {
ret = zs_cpu_notifier(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
- if (notifier_to_errno(ret))
+ if (notifier_to_errno(ret)) {
+ cpu_notifier_register_done();
goto fail;
+ }
}
+
+ cpu_notifier_register_done();
+
return 0;
fail:
zs_exit();