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 <rostedt@goodmis.org>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

diff --git a/drivers/thermal/x86_pkg_temp_thermal.c b/drivers/thermal/x86_pkg_temp_thermal.c
index 810143a..f36950e 100644 (file)
--- 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();