[PATCH 4/6] cpufreq/amd-pstate: Reorder notifier unregistration and floor perf reset

[K Prateek Nayak]

An active power supply notifier can race with amd_pstate_epp_cpu_exit()
trying to reset the floor perf and can overwrite the floor perf set in
MSR_AMD_CPPC_REQ.

Unregister the notifier before setting the floor perf to prevent the
rare race.

Fixes: e30ca6dd5345 ("cpufreq/amd-pstate: Add dynamic energy performance preference")
Reviewed-by: Mario Limonciello <mario.limonciello@xxxxxxx>
Signed-off-by: K Prateek Nayak <kprateek.nayak@xxxxxxx>
---
 drivers/cpufreq/amd-pstate.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 462ddad7bc79e..175925762a93c 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -1982,12 +1982,13 @@ static void amd_pstate_epp_cpu_exit(struct cpufreq_policy *policy)
 	if (cpudata) {
 		union perf_cached perf = READ_ONCE(cpudata->perf);
 
+		if (cpudata->dynamic_epp)
+			amd_pstate_clear_dynamic_epp(policy);
+
 		/* Reset CPPC_REQ MSR to the BIOS value */
 		amd_pstate_update_perf(policy, perf.bios_min_perf, 0U, 0U, 0U, false);
 		amd_pstate_set_floor_perf(policy, cpudata->bios_floor_perf);
 
-		if (cpudata->dynamic_epp)
-			amd_pstate_clear_dynamic_epp(policy);
 		kfree(cpudata);
 		policy->driver_data = NULL;
 	}
-- 
2.34.1