Re: [PATCH 1/1] nfsdctl: check for listeners before starting threads

[Jeff Layton <jlayton@kernel.org>]

On Mon, 2026-03-23 at 14:21 -0400, Olga Kornievskaia wrote:
> When a thread command is executed and yet no listeners have been
> added prior to it, instead of failing with EIO error print an
> informative error. Also, "thread 0" command should not error
> regardless of the listener status.
> 
> Signed-off-by: Olga Kornievskaia <okorniev@redhat.com>
> ---
>  utils/nfsdctl/nfsdctl.c | 52 ++++++++++++++++++++++++++++++++---------
>  1 file changed, 41 insertions(+), 11 deletions(-)
> 
> diff --git a/utils/nfsdctl/nfsdctl.c b/utils/nfsdctl/nfsdctl.c
> index 6a20d180..d03e2c9f 100644
> --- a/utils/nfsdctl/nfsdctl.c
> +++ b/utils/nfsdctl/nfsdctl.c
> @@ -162,6 +162,9 @@ static const char *nfsd4_ops[] = {
>  	[OP_REMOVEXATTR]	= "OP_REMOVEXATTR",
>  };
>  
> +static int fetch_current_listeners(struct nl_sock *sock);
> +static int print_listeners(int output);
> +
>  static int error_handler(struct sockaddr_nl *nla, struct nlmsgerr *err,
>  			 void *arg)
>  {
> @@ -720,7 +723,7 @@ static int threads_func(struct nl_sock *sock, int argc, char **argv)
>  	uint8_t cmd = NFSD_CMD_THREADS_GET;
>  	int *pool_threads = NULL;
>  	int minthreads = -1;
> -	int opt, pools = 0;
> +	int opt, pools = 0, zero_threads = 0;
>  
>  	optind = 1;
>  	while ((opt = getopt_long(argc, argv, "hm:", threads_options, NULL)) != -1) {
> @@ -762,12 +765,31 @@ static int threads_func(struct nl_sock *sock, int argc, char **argv)
>  			}
>  
>  			pool_threads[i] = strtol(targv[i], &endptr, 0);
> +			if (!pool_threads[i])
> +				zero_threads++;
>  			if (!endptr || *endptr != '\0') {
>  				xlog(L_ERROR, "Invalid threads value %s.", argv[1]);
>  				return 1;
>  			}
>  		}
>  	}
> +	/* check if there are listeners added */
> +	if (fetch_current_listeners(sock)) {
> +		xlog(L_ERROR, "Unable to determine if listeners were added\n");
> +		return 1;
> +	}
> +	if (!print_listeners(0)) {
> +		if (zero_threads && zero_threads == pools) {
> +			/* Note: we can never have a server with threads and no
> +			 * listeners. If we ever add functionality to remove
> +			 * listeners on an active server, we need to revisit this.
> +			 */
> +			return 0;
> +		}
> +		xlog(L_ERROR, "No listeners added, not starting threads\n");
> +		return 1;
> +	}
> +
>  	return threads_doit(sock, cmd, 0, 0, pools, pool_threads, NULL, minthreads);
>  }
>  
> @@ -1077,9 +1099,9 @@ out:
>  	return ret;
>  }
>  
> -static void print_listeners(void)
> +static int print_listeners(int output)

Maybe instead of adding the "output" parameter, you could just add a
count_listeners() function?

Ack on the basic idea though!

>  {
> -	int i;
> +	int i, count = 0;
>  	const char *res;
>  
>  	for (i = 0; i < MAX_NFSD_SOCKETS; ++i) {
> @@ -1098,26 +1120,34 @@ static void print_listeners(void)
>  			res = inet_ntop(AF_INET, &((struct sockaddr_in *)(&sock->ss))->sin_addr,
>  					addr, INET6_ADDRSTRLEN);
>  			port = ((struct sockaddr_in *)(&sock->ss))->sin_port;
> -			if (res == NULL)
> +			if (res == NULL && output)
>  				perror("inet_ntop");
> -			else
> -				printf("%s:%s:%hu\n", sock->name, addr, ntohs(port));
> +			else {
> +				count++;
> +				if (output)
> +					printf("%s:%s:%hu\n", sock->name, addr, ntohs(port));
> +			}
>  			break;
>  		case AF_INET6:
>  			res = inet_ntop(AF_INET6, &((struct sockaddr_in6 *)(&sock->ss))->sin6_addr,
>  					addr, INET6_ADDRSTRLEN);
>  			port = ((struct sockaddr_in6 *)(&sock->ss))->sin6_port;
> -			if (res == NULL)
> +			if (res == NULL && output)
>  				perror("inet_ntop");
> -			else
> -				printf("%s:[%s]:%hu\n", sock->name, addr, ntohs(port));
> +			else {
> +				count++;
> +				if (output)
> +					printf("%s:[%s]:%hu\n", sock->name, addr, ntohs(port));
> +			}
>  			break;
>  		default:
> -			snprintf(addr, INET6_ADDRSTRLEN, "Unknown address family: %d\n",
> +			if (output)
> +				snprintf(addr, INET6_ADDRSTRLEN, "Unknown address family: %d\n",
>  					sock->ss.ss_family);
>  			addr[INET6_ADDRSTRLEN - 1] = '\0';
>  		}
>  	}
> +	return count;
>  }
>  
>  static bool ipv6_is_enabled(void)
> @@ -1394,7 +1424,7 @@ static int listener_func(struct nl_sock *sock, int argc, char ** argv)
>  		return set_listeners(sock);
>  	}
>  
> -	print_listeners();
> +	print_listeners(1);
>  	return 0;
>  }
>  

-- 
Jeff Layton <jlayton@kernel.org>