linux-kernel - Re: [PATCH] watchdog: sp5100_tco: Fix PCI device refcount leak

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Message-ID: <20221123162016.GB2374110@roeck-us.net>
Date:   Wed, 23 Nov 2022 08:20:16 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Xiongfeng Wang <wangxiongfeng2@...wei.com>
Cc:     wim@...ux-watchdog.org, linux-kernel@...r.kernel.org,
        yangyingliang@...wei.com
Subject: Re: [PATCH] watchdog: sp5100_tco: Fix PCI device refcount leak

On Tue, Nov 22, 2022 at 07:56:51PM +0800, Xiongfeng Wang wrote:
> for_each_pci_dev() is implemented by pci_get_device(). The comment of
> pci_get_device() says that it will increase the reference count for the
> returned pci_dev and also decrease the reference count for the input
> pci_dev @from if it is not NULL.
> 
> If we break out for_each_pci_dev() loop with pdev not NULL, we need to
> call pci_dev_put() to decrease the reference count. Add the missing
> pci_dev_put() in error path of sp5100_tco_init() and also when we unload
> module.
> 
> Fixes: 15e28bf13008 ("watchdog: Add support for sp5100 chipset TCO")
> Signed-off-by: Xiongfeng Wang <wangxiongfeng2@...wei.com>

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
>  drivers/watchdog/sp5100_tco.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/watchdog/sp5100_tco.c b/drivers/watchdog/sp5100_tco.c
> index fb426b7d81da..f00f26f90444 100644
> --- a/drivers/watchdog/sp5100_tco.c
> +++ b/drivers/watchdog/sp5100_tco.c
> @@ -599,7 +599,7 @@ static int __init sp5100_tco_init(void)
>  
>  	err = platform_driver_register(&sp5100_tco_driver);
>  	if (err)
> -		return err;
> +		goto put_dev;
>  
>  	sp5100_tco_platform_device =
>  		platform_device_register_simple(TCO_DRIVER_NAME, -1, NULL, 0);
> @@ -612,6 +612,8 @@ static int __init sp5100_tco_init(void)
>  
>  unreg_platform_driver:
>  	platform_driver_unregister(&sp5100_tco_driver);
> +put_dev:
> +	pci_dev_put(sp5100_tco_pci);
>  	return err;
>  }
>  
> @@ -619,6 +621,7 @@ static void __exit sp5100_tco_exit(void)
>  {
>  	platform_device_unregister(sp5100_tco_platform_device);
>  	platform_driver_unregister(&sp5100_tco_driver);
> +	pci_dev_put(sp5100_tco_pci);
>  }
>  
>  module_init(sp5100_tco_init);
> -- 
> 2.20.1
>