linux-kernel - Re: [PATCH] hid: Register debugfs entries before adding device

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Date:	Mon, 15 Mar 2010 14:48:38 +0100 (CET)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Bruno Prémont <bonbons@...ux-vserver.org>
Cc:	Alan Stern <stern@...land.harvard.edu>,
	linux-input@...r.kernel.org, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	"Rick L. Vinyard Jr." <rvinyard@...nmsu.edu>,
	Nicu Pavel <npavel@...ner.com>
Subject: Re: [PATCH] hid: Register debugfs entries before adding device

On Sat, 13 Mar 2010, Bruno Prémont wrote:

> > If the device_add() fails, you should undo the hid_debug_register() 
> > call.
> 
> Well I was wondering why hid_debug_register() was called no matter what
> device_add() returned but didn't dig around what happened when
> hid_add_device() would return an error.
> 
> Looking a few lines further, hid_remove_device() just unregisters debugfs
> entries when status has HID_STAT_ADDED so it definitely makes sense to
> do the proper cleanup (and hid_remove_device() is the only once calling
> hid_debug_unregister())
> 
> So patch for both below:
> 
> 
> 
> 
> Register debugfs entries before calling device_add() so debugfs entries
> are already present when HID driver's probe function gets called on device
> hotplug.
> Also undo debugfs entry registration if device_add() fails so status
> HID_STAT_ADDED and debugfs registration status remain consistent and
> we don't leak the debugfs entries.
> 
> Signed-off-by: Bruno Prémont <bonbons@...ux-vserver.org>
> Cc: Alan Stern <stern@...land.harvard.edu>
> ---
> 
> 
> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> index eabe5f8..709b4d0 100644
> --- a/drivers/hid/hid-core.c
> +++ b/drivers/hid/hid-core.c
> @@ -1759,11 +1759,12 @@ int hid_add_device(struct hid_device *hdev)
>  	dev_set_name(&hdev->dev, "%04X:%04X:%04X.%04X", hdev->bus,
>  		     hdev->vendor, hdev->product, atomic_inc_return(&id));
>  
> +	hid_debug_register(hdev, dev_name(&hdev->dev));
>  	ret = device_add(&hdev->dev);
>  	if (!ret)
>  		hdev->status |= HID_STAT_ADDED;
> -
> -	hid_debug_register(hdev, dev_name(&hdev->dev));
> +	else
> +		hid_debug_unregister(hdev);
>  
>  	return ret;

Applied, thank you Bruno.

-- 
Jiri Kosina
SUSE Labs, Novell Inc.
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