Re: [PATCH 19/28] verbs: Avoid gcc 6.1 warning -Wunused-variable

[Yishai Hadas <yishaih-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>]

On 9/6/2016 12:08 AM, Jason Gunthorpe wrote:
> gcc remarks:
>
> ../libibverbs/src/neigh.c:339:6: warning: 'sock_fd' may be used uninitialized in this function [-Wmaybe-uninitialized]
>   err = try_send_to(sock_fd, buff, sizeof(buff), &addr_dst);


Why not just initializing 'sock_fd' to any value (e.g. to 0) when it's 
declared and drop all below patch ? as the code checks the return code 
from create_socket() it should be safe.

> But this is bogus because create_socket will always return
> an error if it does not set psock_fd. It looks like the
> insane if logic is just a tish too much for gcc to handle.
>
> Since the result of create_socket is discarded anyhow, simplify the
> tortured logic.
>
> Signed-off-by: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
> ---
>  libibverbs/src/neigh.c | 12 +++++-------
>  1 file changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/libibverbs/src/neigh.c b/libibverbs/src/neigh.c
> index 799b810a9ec4..dc8c2bc99ae3 100644
> --- a/libibverbs/src/neigh.c
> +++ b/libibverbs/src/neigh.c
> @@ -207,7 +207,7 @@ static int create_socket(struct get_neigh_handler *neigh_handler,
>  				    &addr_src.len);
>  	if (err) {
>  		errno = EADDRNOTAVAIL;
> -		return err;
> +		return -1;
>  	}
>
>  	addr_dst->len = sizeof(addr_dst->sktaddr);
> @@ -216,24 +216,22 @@ static int create_socket(struct get_neigh_handler *neigh_handler,
>  				    &addr_dst->len);
>  	if (err) {
>  		errno = EADDRNOTAVAIL;
> -		return err;
> +		return -1;
>  	}
>
>  	err = set_link_port(&addr_dst->sktaddr, PORT_DISCARD,
>  			    neigh_handler->oif);
>  	if (err)
> -		return err;
> +		return -1;
>
>  	sock_fd = socket(addr_dst->sktaddr.s.sa_family,
>  			 SOCK_DGRAM | SOCK_CLOEXEC, 0);
>  	if (sock_fd == -1)
> -		return errno ? -errno : -1;
> +		return -1;
>  	err = bind(sock_fd, &addr_src.sktaddr.s, addr_src.len);
>  	if (err) {
> -		int bind_err = -errno;
> -
>  		close(sock_fd);
> -		return bind_err ?: EADDRNOTAVAIL;
> +		return -1;
>  	}
>
>  	*psock_fd = sock_fd;
>

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