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

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Date:   Thu, 19 Jan 2023 15:02:40 +0000
From:   Caleb Connolly <caleb.connolly@...aro.org>
To:     Viresh Kumar <viresh.kumar@...aro.org>,
        "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>
Cc:     linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...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 18/01/2023 08:38, Viresh Kumar 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>

Tested-by: Caleb Connolly <caleb.connolly@...aro.org>

Thanks for sending this, with this I no longer hit the splats when
get_max_state() fails.
> ---
> 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);

-- 
Kind Regards,
Caleb (they/them)