Thanks. How did you trigger this error condition? Is it a code review or
you have some way to reproduce?
Regards,
Srinivas
On 07/16/2013 11:02 AM, Steven Rostedt wrote:
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 <[email protected]>
diff --git a/drivers/thermal/x86_pkg_temp_thermal.c
b/drivers/thermal/x86_pkg_temp_thermal.c
index 5de56f6..d47624c 100644
--- a/drivers/thermal/x86_pkg_temp_thermal.c
+++ b/drivers/thermal/x86_pkg_temp_thermal.c
@@ -592,7 +592,6 @@ 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();
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