Re: [PATCH] cpufreq: amd-pstate: fix kernel hang issue while amd-pstate unregistering

Wyes Karny
2023-01-09T15:41:46Z

On 1/6/2023 11:18 AM, Perry Yuan wrote:
> 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.
>
> Acked-by: Huang Rui <ray.huang@amd.com>
> Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
> Signed-off-by: Perry Yuan <perry.yuan@amd.com>

Tested-by: Wyes Karny <wyes.karny@amd.com>

> Cc: stable@vger.kernel.org
> ---
> drivers/cpufreq/amd-pstate.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 204e39006dda..c17bd845f5fc 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/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)

--
Thanks & Regards,
Wyes