linux-kernel - Re: [PATCH] powercap: dtpm_cpu: Fix error check against freq_qos_add

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Message-ID: <CAJZ5v0ho5jURiLqZ-sPFn1Vc0Wtz3Bd0C_-XV7d3HRzQ_Rw4Eg@mail.gmail.com>
Date: Fri, 16 Feb 2024 20:06:55 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Daniel Lezcano <daniel.lezcano@...aro.org>
Cc: rafael@...nel.org, linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Daniel Lezcano <daniel.lezcano@...nel.org>
Subject: Re: [PATCH] powercap: dtpm_cpu: Fix error check against freq_qos_add_request()

On Tue, Feb 13, 2024 at 11:39 PM Daniel Lezcano
<daniel.lezcano@...aro.org> wrote:
>
> The caller of the function freq_qos_add_request() checks again a non
> zero value but freq_qos_add_request() can return '1' if the request
> already exists. Therefore, the setup function fails while the QoS
> request actually did not failed.
>
> Fix that by changing the check against a negative value like all the
> other callers of the function.
>
> Fixes: 0e8f68d7f0485 ("Add CPU energy model based support")
> Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
> ---
>  drivers/powercap/dtpm_cpu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/powercap/dtpm_cpu.c b/drivers/powercap/dtpm_cpu.c
> index 9193c3b8edeb..ae7ee611978b 100644
> --- a/drivers/powercap/dtpm_cpu.c
> +++ b/drivers/powercap/dtpm_cpu.c
> @@ -219,7 +219,7 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
>         ret = freq_qos_add_request(&policy->constraints,
>                                    &dtpm_cpu->qos_req, FREQ_QOS_MAX,
>                                    pd->table[pd->nr_perf_states - 1].frequency);
> -       if (ret)
> +       if (ret < 0)
>                 goto out_dtpm_unregister;
>
>         cpufreq_cpu_put(policy);
> --

Applied as 6.9 material, thanks!