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thermal: intel_powerclamp: Use get_cpu() instead of smp_processor_id() to avoid crash

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When CPU 0 is offline and intel_powerclamp is used to inject
idle, it generates kernel BUG:

BUG: using smp_processor_id() in preemptible [00000000] code: bash/15687
caller is debug_smp_processor_id+0x17/0x20
CPU: 4 PID: 15687 Comm: bash Not tainted 5.19.0-rc7+ #57
Call Trace:
<TASK>
dump_stack_lvl+0x49/0x63
dump_stack+0x10/0x16
check_preemption_disabled+0xdd/0xe0
debug_smp_processor_id+0x17/0x20
powerclamp_set_cur_state+0x7f/0xf9 [intel_powerclamp]
...
...

Here CPU 0 is the control CPU by default and changed to the current CPU,
if CPU 0 offlined. This check has to be performed under cpus_read_lock(),
hence the above warning.

Use get_cpu() instead of smp_processor_id() to avoid this BUG.

Suggested-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
[ rjw: Subject edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Srinivas Pandruvada 2022-09-20 04:06:57 -07:00 committed by Rafael J. Wysocki
parent e9a7c526c2
commit 68b99e94a4
1 changed files with 4 additions and 2 deletions
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6
drivers/thermal/intel/intel_powerclamp.c
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@ -532,8 +532,10 @@ static int start_power_clamp(void)
/* prefer BSP */
control_cpu = 0;
if (!cpu_online(control_cpu))
control_cpu = smp_processor_id();
if (!cpu_online(control_cpu)) {
control_cpu = get_cpu();
put_cpu();
}
clamping = true;
schedule_delayed_work(&poll_pkg_cstate_work, 0);