linux-kernel - Re: [PATCH] Free struct device in fw_dev

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Date:	Wed, 8 Jul 2009 12:28:52 +0200
From:	Cornelia Huck <cornelia.huck@...ibm.com>
To:	Catalin Marinas <catalin.marinas@....com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ming Lei <tom.leiming@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Free struct device in fw_dev_release()

On Wed, 08 Jul 2009 11:17:40 +0100,
Catalin Marinas <catalin.marinas@....com> wrote:

> The f_dev in _request_firmware() is allocated via the fw_setup_device()
> and fw_register_device() calls and its class set to firmware_class (the
> class release function is fw_dev_release).
> 
> Commit 6acf70f078ca replaced the kfree(dev) in fw_dev_release() with a
> put_device() call but my understanding is that the release function is
> called via put_device -> kobject_put -> kref_put -> koject_release etc.
> and it should call kfree since it's the last to see this device
> structure alive.
> 
> Because of that, the _request_firmware() function on its -ENOENT error
> path only calls device_unregister(f_dev) which would eventually call
> fw_dev_release() but there is no kfree (the subsequent put_device call
> would just make the kref negative).
> 
> Signed-off-by: Catalin Marinas <catalin.marinas@....com>
> Cc: Cornelia Huck <cornelia.huck@...ibm.com>

Acked-by: Cornelia Huck <cornelia.huck@...ibm.com>

> Acked-by: Ming Lei <tom.leiming@...il.com>
> ---
>  drivers/base/firmware_class.c |    6 ++----
>  1 files changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
> index ddeb819..fc46653 100644
> --- a/drivers/base/firmware_class.c
> +++ b/drivers/base/firmware_class.c
> @@ -357,7 +357,7 @@ static void fw_dev_release(struct device *dev)
>  	kfree(fw_priv->pages);
>  	kfree(fw_priv->fw_id);
>  	kfree(fw_priv);
> -	put_device(dev);
> +	kfree(dev);
> 
>  	module_put(THIS_MODULE);
>  }
> @@ -408,13 +408,11 @@ static int fw_register_device(struct device **dev_p, const char *fw_name,
>  	if (retval) {
>  		dev_err(device, "%s: device_register failed\n", __func__);
>  		put_device(f_dev);
> -		goto error_kfree_fw_id;
> +		return retval;
>  	}
>  	*dev_p = f_dev;
>  	return 0;
> 
> -error_kfree_fw_id:
> -	kfree(fw_priv->fw_id);
>  error_kfree:
>  	kfree(f_dev);
>  	kfree(fw_priv);
> 
--
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