linux-kernel - Re: [PATCH 06/13] ocfs2: use new sysctl subdir helper register_sysctl

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Message-ID: <202005290121.C78B4AC@keescook>
Date:   Fri, 29 May 2020 01:23:19 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Luis Chamberlain <mcgrof@...nel.org>
Cc:     yzaikin@...gle.com, nixiaoming@...wei.com, ebiederm@...ssion.com,
        axboe@...nel.dk, clemens@...isch.de, arnd@...db.de,
        gregkh@...uxfoundation.org, jani.nikula@...ux.intel.com,
        joonas.lahtinen@...ux.intel.com, rodrigo.vivi@...el.com,
        airlied@...ux.ie, daniel@...ll.ch, benh@...nel.crashing.org,
        rdna@...com, viro@...iv.linux.org.uk, mark@...heh.com,
        jlbec@...lplan.org, joseph.qi@...ux.alibaba.com, vbabka@...e.cz,
        sfr@...b.auug.org.au, jack@...e.cz, amir73il@...il.com,
        rafael@...nel.org, tytso@....edu, julia.lawall@...6.fr,
        akpm@...ux-foundation.org, intel-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, linuxppc-dev@...ts.ozlabs.org,
        ocfs2-devel@....oracle.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 06/13] ocfs2: use new sysctl subdir helper
 register_sysctl_subdir()

On Fri, May 29, 2020 at 07:41:01AM +0000, Luis Chamberlain wrote:
> This simplifies the code considerably. The following coccinelle
> SmPL grammar rule was used to transform this code.
> 
> // pycocci sysctl-subdir.cocci fs/ocfs2/stackglue.c
> 
> @c1@
> expression E1;
> identifier subdir, sysctls;
> @@
> 
> static struct ctl_table subdir[] = {
> 	{
> 		.procname = E1,
> 		.maxlen = 0,
> 		.mode = 0555,
> 		.child = sysctls,
> 	},
> 	{ }
> };
> 
> @c2@
> identifier c1.subdir;
> 
> expression E2;
> identifier base;
> @@
> 
> static struct ctl_table base[] = {
> 	{
> 		.procname = E2,
> 		.maxlen = 0,
> 		.mode = 0555,
> 		.child = subdir,
> 	},
> 	{ }
> };
> 
> @c3@
> identifier c2.base;
> identifier header;
> @@
> 
> header = register_sysctl_table(base);
> 
> @r1 depends on c1 && c2 && c3@
> expression c1.E1;
> identifier c1.subdir, c1.sysctls;
> @@
> 
> -static struct ctl_table subdir[] = {
> -	{
> -		.procname = E1,
> -		.maxlen = 0,
> -		.mode = 0555,
> -		.child = sysctls,
> -	},
> -	{ }
> -};
> 
> @r2 depends on c1 && c2 && c3@
> identifier c1.subdir;
> 
> expression c2.E2;
> identifier c2.base;
> @@
> -static struct ctl_table base[] = {
> -	{
> -		.procname = E2,
> -		.maxlen = 0,
> -		.mode = 0555,
> -		.child = subdir,
> -	},
> -	{ }
> -};
> 
> @r3 depends on c1 && c2 && c3@
> expression c1.E1;
> identifier c1.sysctls;
> expression c2.E2;
> identifier c2.base;
> identifier c3.header;
> @@
> 
> header =
> -register_sysctl_table(base);
> +register_sysctl_subdir(E2, E1, sysctls);
> 
> Generated-by: Coccinelle SmPL
> 
> Signed-off-by: Luis Chamberlain <mcgrof@...nel.org>
> ---
>  fs/ocfs2/stackglue.c | 27 ++++-----------------------
>  1 file changed, 4 insertions(+), 23 deletions(-)
> 
> diff --git a/fs/ocfs2/stackglue.c b/fs/ocfs2/stackglue.c
> index a191094694c6..addafced7f59 100644
> --- a/fs/ocfs2/stackglue.c
> +++ b/fs/ocfs2/stackglue.c
> @@ -677,28 +677,8 @@ static struct ctl_table ocfs2_mod_table[] = {
>  	},
>  	{ }
>  };
> -
> -static struct ctl_table ocfs2_kern_table[] = {
> -	{
> -		.procname	= "ocfs2",
> -		.data		= NULL,
> -		.maxlen		= 0,
> -		.mode		= 0555,
> -		.child		= ocfs2_mod_table
> -	},
> -	{ }
> -};
> -
> -static struct ctl_table ocfs2_root_table[] = {
> -	{
> -		.procname	= "fs",
> -		.data		= NULL,
> -		.maxlen		= 0,
> -		.mode		= 0555,
> -		.child		= ocfs2_kern_table
> -	},
> -	{ }
> -};
> +	.data		= NULL,
> +	.data		= NULL,

The conversion script doesn't like the .data field assignments. ;)

Was this series built with allmodconfig? I would have expected this to
blow up very badly. :)

-- 
Kees Cook