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

From: Al Viro
Date: Wed Jan 08 2020 - 16:39:26 EST


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@xxxxxxxx>
> ---
> 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...