linux-kernel - Re: [PATCH] Bluetooth: vhci: manage mutex with cleanup helpers

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Message-ID: <2024081309-lion-overlying-16a1@gregkh>
Date: Tue, 13 Aug 2024 14:38:38 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: "Yo-Jung (Leo) Lin" <0xff07@...il.com>
Cc: linux-kernel-mentees@...ts.linuxfoundation.org, ricardo@...liere.net,
	skhan@...uxfoundation.org, Marcel Holtmann <marcel@...tmann.org>,
	Luiz Augusto von Dentz <luiz.dentz@...il.com>,
	linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Bluetooth: vhci: manage mutex with cleanup helpers

On Tue, Aug 13, 2024 at 08:18:28PM +0800, Yo-Jung (Leo) Lin wrote:
> Use macros in liunx/cleanup.h for automatic resource cleanup.

That says what you do, but not _why_ you want to do it.

> 
> Signed-off-by: Yo-Jung (Leo) Lin <0xff07@...il.com>
> ---
>  drivers/bluetooth/hci_vhci.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/bluetooth/hci_vhci.c b/drivers/bluetooth/hci_vhci.c
> index c4046f8f1985..70f0c28372ec 100644
> --- a/drivers/bluetooth/hci_vhci.c
> +++ b/drivers/bluetooth/hci_vhci.c
> @@ -19,6 +19,7 @@
>  #include <linux/errno.h>
>  #include <linux/sched.h>
>  #include <linux/poll.h>
> +#include <linux/cleanup.h>
>  
>  #include <linux/skbuff.h>
>  #include <linux/miscdevice.h>
> @@ -468,9 +469,9 @@ static int vhci_create_device(struct vhci_data *data, __u8 opcode)
>  {
>  	int err;
>  
> -	mutex_lock(&data->open_mutex);
> -	err = __vhci_create_device(data, opcode);
> -	mutex_unlock(&data->open_mutex);
> +	scoped_guard(mutex, &data->open_mutex) {
> +		err = __vhci_create_device(data, opcode);
> +	}

This isn't correct, but also, it's not needed at all :(

greg k-h