linux-kernel - Re: [PATCH v9 04/13] cpufreq: amd-pstate: fix kernel hang issue while amd-pstate unregistering

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Date:   Tue, 27 Dec 2022 08:23:53 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Perry Yuan <perry.yuan@....com>
Cc:     rafael.j.wysocki@...el.com, Mario.Limonciello@....com,
        ray.huang@....com, Deepak.Sharma@....com, Nathan.Fontenot@....com,
        Alexander.Deucher@....com, Shimmer.Huang@....com,
        Xiaojian.Du@....com, Li.Meng@....com, wyes.karny@....com,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v9 04/13] cpufreq: amd-pstate: fix kernel hang issue
 while amd-pstate unregistering

On 26-12-22, 00:34, 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@....com>
> Reviewed-by: Mario Limonciello <mario.limonciello@....com>
> Signed-off-by: Perry Yuan <perry.yuan@....com>
> Cc: stable@...r.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)

This should have been sent separately and not in this series. It is a
bug fix, which could have been merged in the 6.1 itself and now is
candidate for 6.2-rc1, while the rest of the series needs to wait for
6.3.

-- 
viresh