Re: [dpdk-dev] [PATCH v3 3/3] examples/l3fwd: Handle SIGINT and SIGTERM in l3fwd

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

> -----Original Message-----
> From: Wang, Zhihong
> Sent: Tuesday, December 29, 2015 1:21 AM
> To: dev@dpdk.org
> Cc: Ananyev, Konstantin; stephen@networkplumber.org; Qiu, Michael; Wang, Zhihong
> Subject: [PATCH v3 3/3] examples/l3fwd: Handle SIGINT and SIGTERM in l3fwd
> 
> Handle SIGINT and SIGTERM in l3fwd.
> 
> Signed-off-by: Zhihong Wang <zhihong.wang@intel.com>
> Acked-by: Michael Qiu <michael.qiu@intel.com>
> ---
>  examples/l3fwd/main.c | 129 +++++++++++++++++++++++++++++++++++++++++---------
>  1 file changed, 107 insertions(+), 22 deletions(-)
> 
> diff --git a/examples/l3fwd/main.c b/examples/l3fwd/main.c
> index 5b0c2dd..c766cf5 100644
> --- a/examples/l3fwd/main.c
> +++ b/examples/l3fwd/main.c
> @@ -41,6 +41,9 @@
>  #include <stdarg.h>
>  #include <errno.h>
>  #include <getopt.h>
> +#include <signal.h>
> +#include <unistd.h>
> +#include <stdbool.h>
> 
>  #include <rte_common.h>
>  #include <rte_vect.h>
> @@ -75,6 +78,10 @@
>  #include <cmdline_parse.h>
>  #include <cmdline_parse_etheraddr.h>
> 
> +static volatile bool port_started;
> +static volatile bool force_quit;
> +static volatile int signo_quit;
> +
>  #define APP_LOOKUP_EXACT_MATCH          0
>  #define APP_LOOKUP_LPM                  1
>  #define DO_RFC_1812_CHECKS
> @@ -1553,8 +1560,7 @@ main_loop(__attribute__((unused)) void *dummy)
>  			portid, queueid);
>  	}
> 
> -	while (1) {
> -
> +	while (!force_quit) {
>  		cur_tsc = rte_rdtsc();
> 
>  		/*
> @@ -2516,8 +2522,12 @@ check_all_ports_link_status(uint8_t port_num, uint32_t port_mask)
>  	printf("\nChecking link status");
>  	fflush(stdout);
>  	for (count = 0; count <= MAX_CHECK_TIME; count++) {
> +		if (force_quit)
> +			return;
>  		all_ports_up = 1;
>  		for (portid = 0; portid < port_num; portid++) {
> +			if (force_quit)
> +				return;
>  			if ((port_mask & (1 << portid)) == 0)
>  				continue;
>  			memset(&link, 0, sizeof(link));
> @@ -2559,6 +2569,76 @@ check_all_ports_link_status(uint8_t port_num, uint32_t port_mask)
>  	}
>  }
> 
> +static uint8_t
> +start_ports(void)
> +{
> +	unsigned portid, nb_ports, avail_ports;
> +	int ret;
> +
> +	nb_ports = rte_eth_dev_count();
> +	avail_ports = 0;
> +	for (portid = 0; portid < nb_ports; portid++) {
> +		if ((enabled_port_mask & (1 << portid)) == 0)
> +			continue;
> +		avail_ports++;
> +		port_started = true;

Why do you need it at each iteration?

> +		printf("Starting port %d...", portid);
> +		ret = rte_eth_dev_start(portid);
> +		if (ret < 0)
> +			rte_exit(EXIT_FAILURE,
> +					"rte_eth_dev_start: err=%d, port=%d\n",
> +					ret, portid);
> +		/*
> +		 * If enabled, put device in promiscuous mode.
> +		 * This allows IO forwarding mode to forward packets
> +		 * to itself through 2 cross-connected  ports of the
> +		 * target machine.
> +		 */
> +		if (promiscuous_on)
> +			rte_eth_promiscuous_enable(portid);
> +		printf(" Done\n");
> +	}
> +
> +	return avail_ports;
> +}
> +
> +static void
> +stop_ports(void)
> +{
> +	unsigned portid, nb_ports;
> +
> +	nb_ports = rte_eth_dev_count();
> +	for (portid = 0; portid < nb_ports; portid++) {
> +		if ((enabled_port_mask & (1 << portid)) == 0)
> +			continue;
> +		printf("Stopping port %d...", portid);
> +		rte_eth_dev_stop(portid);
> +		rte_eth_dev_close(portid);
> +		printf(" Done\n");
> +	}
> +	port_started = false;
> +}
> +
> +static void
> +signal_handler(int signum)
> +{
> +	if (signum == SIGINT || signum == SIGTERM) {
> +		printf("\nSignal %d received, preparing to exit...\n",
> +				signum);
> +		if (port_started) {
> +			printf("Ports started already...\n");
> +			signo_quit = signum;
> +			force_quit = true;
> +		} else {


Hmm, and what if signal_handler() would be executed not in the context of master lcore?
Then there could be a raise condition, and you could end up here, while master lcore
would be in the middle of start_ports()->rte_eth_dev_start().
Probably not a big deal, but why do you need this  if (port_started) {...} else {...} at all?
Why not just:

signal_handler(int signum)
{
	signo_quit = signum;
	force_quit = true;
}
?

Konstantin

> +			printf("Ports not started yet...\n");
> +			printf("Bye...\n");
> +			/* exit with the expected status */
> +			signal(signum, SIG_DFL);
> +			kill(getpid(), signum);
> +		}
> +	}
> +}
> +
>  int
>  main(int argc, char **argv)
>  {
> @@ -2571,6 +2651,12 @@ main(int argc, char **argv)
>  	unsigned lcore_id;
>  	uint32_t n_tx_queue, nb_lcores;
>  	uint8_t portid, nb_rx_queue, queue, socketid;
> +	uint8_t avail_ports;
> +
> +	port_started = false;
> +	force_quit = false;
> +	signal(SIGINT, signal_handler);
> +	signal(SIGTERM, signal_handler);
> 
>  	/* init EAL */
>  	ret = rte_eal_init(argc, argv);
> @@ -2711,34 +2797,33 @@ main(int argc, char **argv)
>  	printf("\n");
> 
>  	/* start ports */
> -	for (portid = 0; portid < nb_ports; portid++) {
> -		if ((enabled_port_mask & (1 << portid)) == 0) {
> -			continue;
> -		}
> -		/* Start device */
> -		ret = rte_eth_dev_start(portid);
> -		if (ret < 0)
> -			rte_exit(EXIT_FAILURE, "rte_eth_dev_start: err=%d, port=%d\n",
> -				ret, portid);
> +	avail_ports = start_ports();
> 
> -		/*
> -		 * If enabled, put device in promiscuous mode.
> -		 * This allows IO forwarding mode to forward packets
> -		 * to itself through 2 cross-connected  ports of the
> -		 * target machine.
> -		 */
> -		if (promiscuous_on)
> -			rte_eth_promiscuous_enable(portid);
> +	if (!avail_ports) {
> +		rte_exit(EXIT_FAILURE,
> +			"All ports are disabled, please check portmask...\n");
>  	}
> 
>  	check_all_ports_link_status((uint8_t)nb_ports, enabled_port_mask);
> 
> +	ret = 0;
>  	/* launch per-lcore init on every lcore */
>  	rte_eal_mp_remote_launch(main_loop, NULL, CALL_MASTER);
>  	RTE_LCORE_FOREACH_SLAVE(lcore_id) {
> -		if (rte_eal_wait_lcore(lcore_id) < 0)
> -			return -1;
> +		if (rte_eal_wait_lcore(lcore_id) < 0) {
> +			ret = -1;
> +			break;
> +		}
>  	}
> 
> -	return 0;
> +	/* stop ports */
> +	stop_ports();
> +	printf("Bye...\n");
> +	/* exit with the expected status */
> +	if (force_quit) {
> +		signal(signo_quit, SIG_DFL);
> +		kill(getpid(), signo_quit);
> +	}
> +
> +	return ret;
>  }
> --
> 2.5.0