From: Steven Rostedt Date: Tue, 16 Jul 2013 18:02:28 +0000 (-0400) Subject: Thermal: Fix lockup of cpu_down() X-Git-Tag: firefly_0821_release~176^2~5656^2 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=ace120dcf23b3bbba00d797a898481997381052f;p=firefly-linux-kernel-4.4.55.git Thermal: Fix lockup of cpu_down() Commit f1a18a105 "Thermal: CPU Package temperature thermal" had code that did a get_online_cpus(), run a loop and then do a put_online_cpus(). The problem is that the loop had an error exit that would skip the put_online_cpus() part. In the error exit part of the function, it also did a get_online_cpus(), run a loop and then put_online_cpus(). The only way to get to the error exit part is with get_online_cpus() already performed. If this error condition is hit, the system will be prevented from taking CPUs offline. The process taking the CPU offline will lock up hard. Removing the get_online_cpus() removes the lockup as the hotplug CPU refcount is back to zero. This was bisected with ktest. Signed-off-by: Steven Rostedt Signed-off-by: Zhang Rui --- diff --git a/drivers/thermal/x86_pkg_temp_thermal.c b/drivers/thermal/x86_pkg_temp_thermal.c index 810143a6aa33..f36950e4134f 100644 --- a/drivers/thermal/x86_pkg_temp_thermal.c +++ b/drivers/thermal/x86_pkg_temp_thermal.c @@ -599,7 +599,6 @@ static int __init pkg_temp_thermal_init(void) return 0; err_ret: - get_online_cpus(); for_each_online_cpu(i) put_core_offline(i); put_online_cpus();