Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20220714134342.3498384-1-quic_kshivnan@quicinc.com>
In-Reply-To: <20220714134342.3498384-1-quic_kshivnan@quicinc.com>
From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Thu, 14 Jul 2022 20:45:21 +0200
Message-ID: <CAJZ5v0hQ=YXEysP0vWruwiPV+ubQoc_rTwQ1K=Y3p7hjm8UFMg@mail.gmail.com>
Subject: Re: [PATCH v2 1/1] PM: QoS: Add check to make sure CPU freq is non-negative
To:     Shivnandan Kumar <quic_kshivnan@quicinc.com>
Cc:     "Rafael J. Wysocki" <rafael@kernel.org>,
        Len Brown <len.brown@intel.com>, Pavel Machek <pavel@ucw.cz>,
        Linux PM <linux-pm@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Thu, Jul 14, 2022 at 3:44 PM Shivnandan Kumar
<quic_kshivnan@quicinc.com> wrote:
>
>         CPU frequency should never be negative.
>         If some client driver calls freq_qos_update_request with some
>         value greater than INT_MAX, then it will set max CPU freq at
>         fmax but it will add plist node with some negative priority.
>         plist node has priority from INT_MIN (highest) to INT_MAX
>         (lowest). Once priority is set as negative, another client
>         will not be able to reduce CPU frequency. Adding check to
>         make sure CPU freq is non-negative will fix this problem.

The changelog doesn't match the patch any more, please rewrite it.

>
> Signed-off-by: Shivnandan Kumar <quic_kshivnan@quicinc.com>
>
> ---
> v1->v2
>         -addressed comments from Rafael
>         -changed commit text accordingly
>
>  kernel/power/qos.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/power/qos.c b/kernel/power/qos.c
> index ec7e1e85923e..27e6596f287a 100644
> --- a/kernel/power/qos.c
> +++ b/kernel/power/qos.c
> @@ -531,7 +531,7 @@ int freq_qos_add_request(struct freq_constraints *qos,
>  {
>         int ret;
>
> -       if (IS_ERR_OR_NULL(qos) || !req)
> +       if (IS_ERR_OR_NULL(qos) || !req || value < FREQ_QOS_MIN_DEFAULT_VALUE)
>                 return -EINVAL;
>
>         if (WARN(freq_qos_request_active(req),
> @@ -563,7 +563,7 @@ EXPORT_SYMBOL_GPL(freq_qos_add_request);
>   */
>  int freq_qos_update_request(struct freq_qos_request *req, s32 new_value)
>  {
> -       if (!req)
> +       if (!req || new_value < FREQ_QOS_MIN_DEFAULT_VALUE)
>                 return -EINVAL;
>
>         if (WARN(!freq_qos_request_active(req),
> --
> 2.25.1
>