linux-kernel - Re: [PATCH] PNP: add put_device() in pnpbios

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Message-ID: <2025121808-grit-earpiece-51ed@gregkh>
Date: Thu, 18 Dec 2025 11:03:45 +0100
From: Greg KH <gregkh@...uxfoundation.org>
To: Haoxiang Li <lihaoxiang@...c.iscas.ac.cn>
Cc: rafael@...nel.org, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] PNP: add put_device() in pnpbios_init()

On Thu, Dec 18, 2025 at 04:19:55PM +0800, Haoxiang Li wrote:
> If pnp_register_protocol() fails, call put_device()
> to drop the device reference.
> 
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Cc: stable@...r.kernel.org
> Signed-off-by: Haoxiang Li <lihaoxiang@...c.iscas.ac.cn>
> ---
>  drivers/pnp/pnpbios/core.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/pnp/pnpbios/core.c b/drivers/pnp/pnpbios/core.c
> index f7e86ae9f72f..997e0153d6e3 100644
> --- a/drivers/pnp/pnpbios/core.c
> +++ b/drivers/pnp/pnpbios/core.c
> @@ -538,6 +538,7 @@ static int __init pnpbios_init(void)
>  	/* register with the pnp layer */
>  	ret = pnp_register_protocol(&pnpbios_protocol);
>  	if (ret) {
> +		put_device(&pnpbios_protocol.dev)

This feels wrong, as this is a static structure, why would it have a
reference count?  Something is not working properly here if this is
required.

What testing caused this to trigger?  How was this found?

thanks,

greg k-h