Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH] arch: mips: sibyte: Return -EFAULT if copy_to_user()
 fails
To:     Wang Qing <wangqing@vivo.com>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org
References: <1614580437-19660-1-git-send-email-wangqing@vivo.com>
From:   Sergei Shtylyov <sergei.shtylyov@gmail.com>
Organization: Brain-dead Software
Message-ID: <3a7d2007-b7d2-e428-406c-a6804bff6df0@gmail.com>
Date:   Mon, 1 Mar 2021 11:53:01 +0300
User-Agent: Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:78.0) Gecko/20100101
 Thunderbird/78.7.1
MIME-Version: 1.0
In-Reply-To: <1614580437-19660-1-git-send-email-wangqing@vivo.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Precedence: bulk

Hello!

On 01.03.2021 9:33, Wang Qing wrote:

> The copy_to_user() function returns the number of bytes remaining to be
> copied, but we want to return -EFAULT if the copy doesn't complete.

    Then 'err' is hardly a good name for that variable. :-)

> 
> Signed-off-by: Wang Qing <wangqing@vivo.com>
> ---
>   arch/mips/sibyte/common/sb_tbprof.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/mips/sibyte/common/sb_tbprof.c b/arch/mips/sibyte/common/sb_tbprof.c
> index f80d7a7..eac125f
> --- a/arch/mips/sibyte/common/sb_tbprof.c
> +++ b/arch/mips/sibyte/common/sb_tbprof.c
> @@ -465,7 +465,7 @@ static ssize_t sbprof_tb_read(struct file *filp, char *buf,
>   		if (err) {
>   			*offp = cur_off + cur_count - err;
>   			mutex_unlock(&sbp.lock);
> -			return err;
> +			return -EFAULT;
>   		}
>   		pr_debug(DEVNAME ": read from sample %d, %d bytes\n",
>   			 cur_sample, cur_count);

MBR, Sergei