Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Mon, 5 Sep 2022 04:12:11 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     Li zeming <zeming@nfschina.com>
Cc:     mcgrof@kernel.org, keescook@chromium.org, yzaikin@google.com,
        linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] proc/proc_sysctl: Modify the order of scheduling
 function calls
Message-ID: <YxVpCyHBweai9npY@casper.infradead.org>
References: <20220905012925.3117-1-zeming@nfschina.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20220905012925.3117-1-zeming@nfschina.com>
Precedence: bulk

On Mon, Sep 05, 2022 at 09:29:25AM +0800, Li zeming wrote:
> When the ctl_table_header object is judged to be valid, the scheduling
> check is performed again.

No, we want the check in all cases, even if the header is NULL.

> Signed-off-by: Li zeming <zeming@nfschina.com>
> ---
>  fs/proc/proc_sysctl.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
> index 50ba9e4fb284..36921e2ebeb0 100644
> --- a/fs/proc/proc_sysctl.c
> +++ b/fs/proc/proc_sysctl.c
> @@ -1729,11 +1729,10 @@ static void drop_sysctl_table(struct ctl_table_header *header)
>  void unregister_sysctl_table(struct ctl_table_header * header)
>  {
>  	int nr_subheaders;
> -	might_sleep();
> -
>  	if (header == NULL)
>  		return;
>  
> +	might_sleep();
>  	nr_subheaders = count_subheaders(header->ctl_table_arg);
>  	if (unlikely(nr_subheaders > 1)) {
>  		struct ctl_table_header **subheaders;
> -- 
> 2.18.2
>