[PATCH] [net-next] socket: fix unused-function warning

[PATCH] [net-next] socket: fix unused-function warning

[Arnd Bergmann]

When procfs is disabled, the fdinfo code causes a harmless
warning:

net/socket.c:1000:13: error: 'sock_show_fdinfo' defined but not used [-Werror=unused-function]
 static void sock_show_fdinfo(struct seq_file *m, struct file *f)

Change the preprocessor conditional to a compiler conditional
to avoid the warning and let the compiler throw away the
function itself.

Fixes: b4653342b151 ("net: Allow to show socket-specific information in /proc/[pid]/fdinfo/[fd]")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 net/socket.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/net/socket.c b/net/socket.c
index 5230c9e1bdec..444a617819f0 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -151,9 +151,7 @@ static const struct file_operations socket_file_ops = {
 	.sendpage =	sock_sendpage,
 	.splice_write = generic_splice_sendpage,
 	.splice_read =	sock_splice_read,
-#ifdef CONFIG_PROC_FS
-	.show_fdinfo =	sock_show_fdinfo,
-#endif
+	.show_fdinfo =	IS_ENABLED(CONFIG_PROC_FS) ? sock_show_fdinfo : NULL,
 };
 
 /*
-- 
2.20.0

Re: [PATCH] [net-next] socket: fix unused-function warning

[Kirill Tkhai]

On 08.01.2020 00:35, Arnd Bergmann wrote:
> When procfs is disabled, the fdinfo code causes a harmless
> warning:
> 
> net/socket.c:1000:13: error: 'sock_show_fdinfo' defined but not used [-Werror=unused-function]
>  static void sock_show_fdinfo(struct seq_file *m, struct file *f)
> 
> Change the preprocessor conditional to a compiler conditional
> to avoid the warning and let the compiler throw away the
> function itself.
> 
> Fixes: b4653342b151 ("net: Allow to show socket-specific information in /proc/[pid]/fdinfo/[fd]")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Thanks for fixing.

Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com>

> ---
>  net/socket.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/net/socket.c b/net/socket.c
> index 5230c9e1bdec..444a617819f0 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -151,9 +151,7 @@ static const struct file_operations socket_file_ops = {
>  	.sendpage =	sock_sendpage,
>  	.splice_write = generic_splice_sendpage,
>  	.splice_read =	sock_splice_read,
> -#ifdef CONFIG_PROC_FS
> -	.show_fdinfo =	sock_show_fdinfo,
> -#endif
> +	.show_fdinfo =	IS_ENABLED(CONFIG_PROC_FS) ? sock_show_fdinfo : NULL,
>  };
>  
>  /*
> 

Re: [PATCH] [net-next] socket: fix unused-function warning

[David Miller]

From: Arnd Bergmann <arnd@arndb.de>
Date: Tue,  7 Jan 2020 22:35:59 +0100

> When procfs is disabled, the fdinfo code causes a harmless
> warning:
> 
> net/socket.c:1000:13: error: 'sock_show_fdinfo' defined but not used [-Werror=unused-function]
>  static void sock_show_fdinfo(struct seq_file *m, struct file *f)
> 
> Change the preprocessor conditional to a compiler conditional
> to avoid the warning and let the compiler throw away the
> function itself.
> 
> Fixes: b4653342b151 ("net: Allow to show socket-specific information in /proc/[pid]/fdinfo/[fd]")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

This isn't the prettiest thing I've ever seen.

I really think it's nicer to just explicitly put ifdef's around the
forward declaration and the implementation of sock_show_fdinfo().

Alternatively, move the implementation up to the location of the
forward declaration and then you just need one new ifdef guard.

Re: [PATCH] [net-next] socket: fix unused-function warning

[Arnd Bergmann]

On Wed, Jan 8, 2020 at 10:27 PM David Miller <davem@davemloft.net> wrote:
>
> From: Arnd Bergmann <arnd@arndb.de>
> Date: Tue,  7 Jan 2020 22:35:59 +0100
>
> > When procfs is disabled, the fdinfo code causes a harmless
> > warning:
> >
> > net/socket.c:1000:13: error: 'sock_show_fdinfo' defined but not used [-Werror=unused-function]
> >  static void sock_show_fdinfo(struct seq_file *m, struct file *f)
> >
> > Change the preprocessor conditional to a compiler conditional
> > to avoid the warning and let the compiler throw away the
> > function itself.
> >
> > Fixes: b4653342b151 ("net: Allow to show socket-specific information in /proc/[pid]/fdinfo/[fd]")
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>
> This isn't the prettiest thing I've ever seen.
>
> I really think it's nicer to just explicitly put ifdef's around the
> forward declaration and the implementation of sock_show_fdinfo().
>
> Alternatively, move the implementation up to the location of the
> forward declaration and then you just need one new ifdef guard.

My first version just had a __maybe_unused tag on the declaration, but
I was hoping this would be nicer as it avoids the #ifdef.

I'll send the version Al suggested instead, unless you prefer the
__maybe_unused.

      Arnd

Re: [PATCH] [net-next] socket: fix unused-function warning

[Al Viro]

On Tue, Jan 07, 2020 at 10:35:59PM +0100, Arnd Bergmann wrote:
> When procfs is disabled, the fdinfo code causes a harmless
> warning:
> 
> net/socket.c:1000:13: error: 'sock_show_fdinfo' defined but not used [-Werror=unused-function]
>  static void sock_show_fdinfo(struct seq_file *m, struct file *f)
> 
> Change the preprocessor conditional to a compiler conditional
> to avoid the warning and let the compiler throw away the
> function itself.
> 
> Fixes: b4653342b151 ("net: Allow to show socket-specific information in /proc/[pid]/fdinfo/[fd]")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  net/socket.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/net/socket.c b/net/socket.c
> index 5230c9e1bdec..444a617819f0 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -151,9 +151,7 @@ static const struct file_operations socket_file_ops = {
>  	.sendpage =	sock_sendpage,
>  	.splice_write = generic_splice_sendpage,
>  	.splice_read =	sock_splice_read,
> -#ifdef CONFIG_PROC_FS
> -	.show_fdinfo =	sock_show_fdinfo,
> -#endif
> +	.show_fdinfo =	IS_ENABLED(CONFIG_PROC_FS) ? sock_show_fdinfo : NULL,
>  };

Ugh...  So put that ifdef around the definition of sock_show_fdinfo,
with #define sock_show_fdinfo NULL on the other side...