linux-kernel - Re: [PATCH V4 1/3] thermal: core: call put_device() only after device

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Message-ID: <CAJZ5v0j5Rfw7pj05WsNka0BCNOszxsvPuMfNH8Kh88J+QZFHfA@mail.gmail.com>
Date:   Wed, 18 Jan 2023 20:58:10 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Amit Kucheria <amitk@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Yang Yingliang <yangyingliang@...wei.com>,
        linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Caleb Connolly <caleb.connolly@...aro.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V4 1/3] thermal: core: call put_device() only after
 device_register() fails

On Wed, Jan 18, 2023 at 9:38 AM Viresh Kumar <viresh.kumar@...aro.org> wrote:
>
> put_device() shouldn't be called before a prior call to
> device_register(). __thermal_cooling_device_register() doesn't follow
> that properly and needs fixing. Also
> thermal_cooling_device_destroy_sysfs() is getting called unnecessarily
> on few error paths.
>
> Fix all this by placing the calls at the right place.
>
> Based on initial work done by Caleb Connolly.
>
> Fixes: 4748f9687caa ("thermal: core: fix some possible name leaks in error paths")
> Fixes: c408b3d1d9bb ("thermal: Validate new state in cur_state_store()")
> Reported-by: Caleb Connolly <caleb.connolly@...aro.org>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>

OK, so I think that this patch is needed for 6.2 and the other two may
be queued up for later (they do depend on this one, though, of
course).  Is my understanding correct?

> ---
> For v6.2-rc.
>
> V3->V4:
> - The first three versions were sent by Caleb.
> - The new version fixes the current bugs, without looking to optimize the
>   code any further, which is done separately in the next two patches.
>
>  drivers/thermal/thermal_core.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index f17ab2316dbd..77bd47d976a2 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -909,15 +909,20 @@ __thermal_cooling_device_register(struct device_node *np,
>         cdev->devdata = devdata;
>
>         ret = cdev->ops->get_max_state(cdev, &cdev->max_state);
> -       if (ret)
> -               goto out_kfree_type;
> +       if (ret) {
> +               kfree(cdev->type);
> +               goto out_ida_remove;
> +       }
>
>         thermal_cooling_device_setup_sysfs(cdev);
> +
>         ret = dev_set_name(&cdev->device, "cooling_device%d", cdev->id);
>         if (ret) {
> +               kfree(cdev->type);
>                 thermal_cooling_device_destroy_sysfs(cdev);
> -               goto out_kfree_type;
> +               goto out_ida_remove;
>         }
> +
>         ret = device_register(&cdev->device);
>         if (ret)
>                 goto out_kfree_type;
> @@ -943,6 +948,8 @@ __thermal_cooling_device_register(struct device_node *np,
>         thermal_cooling_device_destroy_sysfs(cdev);
>         kfree(cdev->type);
>         put_device(&cdev->device);
> +
> +       /* thermal_release() takes care of the rest */
>         cdev = NULL;
>  out_ida_remove:
>         ida_free(&thermal_cdev_ida, id);
> --
> 2.31.1.272.g89b43f80a514
>