linux-kernel - Re: [PATCH] sparc: add missing put

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Date:   Tue, 18 Jul 2023 11:45:45 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     sunran001@...suo.com, davem@...emloft.net
Cc:     sparclinux@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sparc: add missing put_device()

On 18/07/2023 10:19, sunran001@...suo.com wrote:
> The of_find_device_by_node() takes a reference to the underlying device
> structure, we should release that reference.
> 
> Detected by coccinelle with the following ERRORS:
> ./arch/sparc/kernel/of_device_common.c:23:1-7: ERROR: missing
> put_device; call of_find_device_by_node on line 18, but without a
> corresponding object release within this function.
> ./arch/sparc/kernel/of_device_common.c:36:1-7: ERROR: missing
> put_device; call of_find_device_by_node on line 30, but without a
> corresponding object release within this function.
> ./arch/sparc/kernel/of_device_common.c:50:1-7: ERROR: missing
> put_device; call of_find_device_by_node on line 42, but without a
> corresponding object release within this function.
> 
> Signed-off-by: Ran Sun <sunran001@...suo.com>
> ---
>   arch/sparc/kernel/of_device_common.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/arch/sparc/kernel/of_device_common.c 
> b/arch/sparc/kernel/of_device_common.c
> index 60f86b837658..7851307de6d0 100644
> --- a/arch/sparc/kernel/of_device_common.c
> +++ b/arch/sparc/kernel/of_device_common.c
> @@ -20,6 +20,7 @@ unsigned int irq_of_parse_and_map(struct device_node 
> *node, int index)
>       if (!op || index >= op->archdata.num_irqs)
>           return 0;
> 
> +    put_device(op->dev);
>       return op->archdata.irqs[index];

Device can be gone and freed after the put_device() call. So at least 
put_device() should come after the op->archdata access.

Same applies to all the cases below.

>   }
>   EXPORT_SYMBOL(irq_of_parse_and_map);
> @@ -32,6 +33,7 @@ int of_address_to_resource(struct device_node *node, 
> int index,
>       if (!op || index >= op->num_resources)
>           return -EINVAL;
> 
> +    put_device(op->dev);
>       memcpy(r, &op->archdata.resource[index], sizeof(*r));
>       return 0;
>   }
> @@ -45,6 +47,7 @@ void __iomem *of_iomap(struct device_node *node, int 
> index)
>       if (!op || index >= op->num_resources)
>           return NULL;
> 
> +    put_device(op->dev);
>       r = &op->archdata.resource[index];
> 
>       return of_ioremap(r, 0, resource_size(r), (char *) r->name);

-- 
With best wishes
Dmitry