diff options
| author | Lai Jiangshan <laijs@cn.fujitsu.com> | 2014-07-31 07:30:17 +0400 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2015-01-23 13:33:51 +0300 |
| commit | 4bee96860a65c3a62d332edac331b3cf936ba3ad (patch) | |
| tree | 255638c13a74a54fd7ea71cb4d9dbe0a591a98ce /kernel/smpboot.c | |
| parent | ec6f34e5b552fb0a52e6aae1a5afbbb1605cc6cc (diff) | |
| download | linux-4bee96860a65c3a62d332edac331b3cf936ba3ad.tar.xz | |
smpboot: Add missing get_online_cpus() in smpboot_register_percpu_thread()
The following race exists in the smpboot percpu threads management:
CPU0 CPU1
cpu_up(2)
get_online_cpus();
smpboot_create_threads(2);
smpboot_register_percpu_thread();
for_each_online_cpu();
__smpboot_create_thread();
__cpu_up(2);
This results in a missing per cpu thread for the newly onlined cpu2 and
in a NULL pointer dereference on a consecutive offline of that cpu.
Proctect smpboot_register_percpu_thread() with get_online_cpus() to
prevent that.
[ tglx: Massaged changelog and removed the change in
smpboot_unregister_percpu_thread() because that's an
optimization and therefor not stable material. ]
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: David Rientjes <rientjes@google.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1406777421-12830-1-git-send-email-laijs@cn.fujitsu.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/smpboot.c')
| -rw-r--r-- | kernel/smpboot.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/smpboot.c b/kernel/smpboot.c index f032fb5284e3..40190f28db35 100644 --- a/kernel/smpboot.c +++ b/kernel/smpboot.c @@ -280,6 +280,7 @@ int smpboot_register_percpu_thread(struct smp_hotplug_thread *plug_thread) unsigned int cpu; int ret = 0; + get_online_cpus(); mutex_lock(&smpboot_threads_lock); for_each_online_cpu(cpu) { ret = __smpboot_create_thread(plug_thread, cpu); @@ -292,6 +293,7 @@ int smpboot_register_percpu_thread(struct smp_hotplug_thread *plug_thread) list_add(&plug_thread->list, &hotplug_threads); out: mutex_unlock(&smpboot_threads_lock); + put_online_cpus(); return ret; } EXPORT_SYMBOL_GPL(smpboot_register_percpu_thread); |