linux-kernel - Re: [PATCH] clocksource/drivers/timer-ti-dm: fix child node refcount handling

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Message-ID: <5a535983-6a78-4449-b57b-176869fd55d8@linaro.org>
Date: Mon, 28 Oct 2024 12:24:04 +0100
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Javier Carrasco <javier.carrasco.cruz@...il.com>,
 Thomas Gleixner <tglx@...utronix.de>, Tony Lindgren <tony@...mide.com>
Cc: linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] clocksource/drivers/timer-ti-dm: fix child node refcount
 handling


Hi Javier,

thanks for spotting the issue


On 13/10/2024 12:14, Javier Carrasco wrote:
> of_find_compatible_node() increments the node's refcount, and it must be
> decremented again with a call to of_node_put() when the pointer is no
> longer required to avoid leaking memory.
> 
> Add the missing calls to of_node_put() in dmtimer_percpu_quirck_init()
> for the 'arm_timer' device node.
> 
> Cc: stable@...r.kernel.org
> Fixes: 25de4ce5ed02 ("clocksource/drivers/timer-ti-dm: Handle dra7 timer wrap errata i940")
> Signed-off-by: Javier Carrasco <javier.carrasco.cruz@...il.com>
> ---
>   drivers/clocksource/timer-ti-dm-systimer.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/clocksource/timer-ti-dm-systimer.c b/drivers/clocksource/timer-ti-dm-systimer.c
> index c2dcd8d68e45..23be1d21ce21 100644
> --- a/drivers/clocksource/timer-ti-dm-systimer.c
> +++ b/drivers/clocksource/timer-ti-dm-systimer.c
> @@ -691,8 +691,10 @@ static int __init dmtimer_percpu_quirk_init(struct device_node *np, u32 pa)
>   	arm_timer = of_find_compatible_node(NULL, NULL, "arm,armv7-timer");
>   	if (of_device_is_available(arm_timer)) {
>   		pr_warn_once("ARM architected timer wrap issue i940 detected\n");
> +		of_node_put(arm_timer);
>   		return 0;
>   	}
> +	of_node_put(arm_timer);

Best practice would be to group of_node_put into a single place.

	bool available;

	[ ... ]

	available = of_device_is_available(arm_timer);
	of_node_put(arm_timer);

	if (available) {
		pr_warn_once("ARM architected timer wrap issue i940 detected\n");
		return 0;
	}


>   	if (pa == 0x4882c000)           /* dra7 dmtimer15 */
>   		return dmtimer_percpu_timer_init(np, 0);
> 
> ---
> base-commit: d61a00525464bfc5fe92c6ad713350988e492b88
> change-id: 20241013-timer-ti-dm-systimer-of_node_put-d42735687698
> 
> Best regards,


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