From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Wang, Zhihong" <zhihong.wang@intel.com>
Subject: Re: [PATCH v3 3/3] examples/l3fwd: Handle SIGINT and
 SIGTERM in l3fwd
Date: Wed, 30 Dec 2015 03:15:22 +0000
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> > +static uint8_t
> > +start_ports(void)
> > +{
> > +	unsigned portid, nb_ports, avail_ports;
> > +	int ret;
> > +
> > +	nb_ports =3D rte_eth_dev_count();
> > +	avail_ports =3D 0;
> > +	for (portid =3D 0; portid < nb_ports; portid++) {
> > +		if ((enabled_port_mask & (1 << portid)) =3D=3D 0)
> > +			continue;
> > +		avail_ports++;
> > +		port_started =3D true;
>=20
> Why do you need it at each iteration?

Only become true when the first enabled port about to started. In case ther=
e's no port enabled at all.
In my opinion no need to optimize since it's not performance sensitive and =
the logic is correct :)


>=20
> > +		printf("Starting port %d...", portid);
> > +		ret =3D rte_eth_dev_start(portid);
> > +		if (ret < 0)
> > +			rte_exit(EXIT_FAILURE,
> > +					"rte_eth_dev_start: err=3D%d, port=3D%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
> > +signal_handler(int signum)
> > +{
> > +	if (signum =3D=3D SIGINT || signum =3D=3D SIGTERM) {
> > +		printf("\nSignal %d received, preparing to exit...\n",
> > +				signum);
> > +		if (port_started) {
> > +			printf("Ports started already...\n");
> > +			signo_quit =3D signum;
> > +			force_quit =3D true;
> > +		} else {
>=20
>=20
> 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 m=
aster
> lcore would be in the middle of start_ports()->rte_eth_dev_start().

Good point! Then we need rte_atomic16_cmpset() to avoid the race condition.


> Probably not a big deal, but why do you need this  if (port_started) {...=
} else {...}
> at all?
> Why not just:

If no port has been started, then just kill itself.
This is for cases like when you just started it and then want to shut it do=
wn, it'll wait a long time for initialization (memory, etc.) before the for=
ce_quit signal take effect.


>=20
> signal_handler(int signum)
> {
> 	signo_quit =3D signum;
> 	force_quit =3D true;
> }
> ?
>=20
> Konstantin
>=20
> > +			printf("Ports not started yet...\n");
> > +			printf("Bye...\n");
> > +			/* exit with the expected status */
> > +			signal(signum, SIG_DFL);
> > +			kill(getpid(), signum);
> > +		}
> > +	}
> > +}
> > +