cpufreq: amd-pstate: fix kernel hang issue while amd-pstate unregistering

In the amd_pstate_adjust_perf(), there is one cpufreq_cpu_get() call to
increase increments the kobject reference count of policy and make it as
busy. Therefore, a corresponding call to cpufreq_cpu_put() is needed to
decrement the kobject reference count back, it will resolve the kernel
hang issue when unregistering the amd-pstate driver and register the
`amd_pstate_epp` driver instance.

Fixes: 1d215f0 ("cpufreq: amd-pstate: Add fast switch function for AMD P-State")
Acked-by: Huang Rui <[email protected]>
Reviewed-by: Mario Limonciello <[email protected]>
Tested-by: Wyes Karny <[email protected]>
Signed-off-by: Perry Yuan <[email protected]>
Cc: 5.17+ <[email protected]> # 5.17+
Signed-off-by: Rafael J. Wysocki <[email protected]>

Author: Perry Yuan

drivers/cpufreq/amd-pstate.c

@@ -307,6 +307,7 @@ static void amd_pstate_adjust_perf(unsigned int cpu,
 		max_perf = min_perf;
 
 	amd_pstate_update(cpudata, min_perf, des_perf, max_perf, true);
+	cpufreq_cpu_put(policy);
 }
 
 static int amd_get_min_freq(struct amd_cpudata *cpudata)