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Date:   Sat, 10 Apr 2021 10:58:09 +0200
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Ye Bin <yebin10@huawei.com>
Cc:     Arnd Bergmann <arnd@arndb.de>,
        Michal Simek <michal.simek@xilinx.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        kernel-janitors@vger.kernel.org, Hulk Robot <hulkci@huawei.com>
Subject: Re: [PATCH -next] char: xilinx_hwicap: use DEFINE_MUTEX() for mutex
 lock
Message-ID: <YHFooZWlC+PV1kV0@kroah.com>
References: <20210409095136.2293754-1-yebin10@huawei.com>
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In-Reply-To: <20210409095136.2293754-1-yebin10@huawei.com>
Precedence: bulk

On Fri, Apr 09, 2021 at 05:51:36PM +0800, Ye Bin wrote:
> mutex lock can be initialized automatically with DEFINE_MUTEX()
> rather than explicitly calling mutex_init().
> 
> Reported-by: Hulk Robot <hulkci@huawei.com>
> Signed-off-by: Ye Bin <yebin10@huawei.com>
> ---
>  drivers/char/xilinx_hwicap/xilinx_hwicap.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/char/xilinx_hwicap/xilinx_hwicap.c b/drivers/char/xilinx_hwicap/xilinx_hwicap.c
> index 067396bedf22..4d586233dfa4 100644
> --- a/drivers/char/xilinx_hwicap/xilinx_hwicap.c
> +++ b/drivers/char/xilinx_hwicap/xilinx_hwicap.c
> @@ -111,7 +111,7 @@
>  /* An array, which is set to true when the device is registered. */
>  static DEFINE_MUTEX(hwicap_mutex);
>  static bool probed_devices[HWICAP_DEVICES];
> -static struct mutex icap_sem;
> +static DEFINE_MUTEX(icap_sem);
>  
>  static struct class *icap_class;
>  
> @@ -857,7 +857,6 @@ static int __init hwicap_module_init(void)
>  	int retval;
>  
>  	icap_class = class_create(THIS_MODULE, "xilinx_config");
> -	mutex_init(&icap_sem);
>  
>  	devt = MKDEV(XHWICAP_MAJOR, XHWICAP_MINOR);
>  	retval = register_chrdev_region(devt,
> 

What actually does this help out with?  Why is it wrong to explicitly
call mutex_init() instead of a magic macro?

What good are these changes causing?

thanks,

greg k-h