From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Monjalon <thomas@monjalon.net>
Subject: Re: [PATCH v5 5/5] eal: simplify parameters of hotplug
	functions
Date: Thu, 04 Oct 2018 13:46:54 +0200
Message-ID: <3504838.42QrpyPWfC@xps>
References: <20180907222727.20521-1-thomas@monjalon.net>
 <20181003231046.26772-6-thomas@monjalon.net>
 <20181004094437.yx4tfebyxbsfp6ry@bidouze.vm.6wind.com>
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Cc: dev@dpdk.org, ophirmu@mellanox.com, qi.z.zhang@intel.com,
 ferruh.yigit@intel.com, ktraynor@redhat.com
To: =?ISO-8859-1?Q?Ga=EBtan?= Rivet <gaetan.rivet@6wind.com>
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04/10/2018 11:44, Ga=EBtan Rivet:
> On Thu, Oct 04, 2018 at 01:10:46AM +0200, Thomas Monjalon wrote:
> > --- a/lib/librte_eal/common/eal_common_dev.c
> > +++ b/lib/librte_eal/common/eal_common_dev.c
> > @@ -129,46 +129,61 @@ int rte_eal_dev_detach(struct rte_device *dev)
> > =20
> >  int
> >  rte_eal_hotplug_add(const char *busname, const char *devname,
> > -		    const char *devargs)
> > +		    const char *drvargs)
> >  {
> > -	struct rte_bus *bus;
> > -	struct rte_device *dev;
> > -	struct rte_devargs *da;
> >  	int ret;
> > +	char *devargs =3D NULL;
> > +	int size, length =3D -1;
> > =20
> > -	bus =3D rte_bus_find_by_name(busname);
> > -	if (bus =3D=3D NULL) {
> > -		RTE_LOG(ERR, EAL, "Cannot find bus (%s)\n", busname);
> > -		return -ENOENT;
> > -	}
> > +	do { /* 2 iterations: first is to know string length */
> > +		size =3D length + 1;
> > +		length =3D snprintf(devargs, size, "%s:%s,%s", busname, devname, drv=
args);
> > +		if (length >=3D size)
> > +			devargs =3D malloc(length + 1);
> > +		if (devargs =3D=3D NULL)
> > +			return -ENOMEM;
> > +	} while (size =3D=3D 0);
>=20
> I don't see a good reason for writing it this way.
> You use an additional state (size) and complicate something that is
> pretty straightforward. To make sure no error was written here, I had to
> do step-by-step careful reading, this should not be required by clean
> code.
>=20
> You should remove this loop, which then allow removing size, and forces u=
sing
> simple code-flow.

The only reason for this loop is to avoid duplicating the snprintf format
in two calls.

It could be replaced by this:

	length =3D snprintf(devargs, 0, "%s:%s,%s", busname, devname, drvargs);
	if (length < 0)
		return -EINVAL;
	devargs =3D malloc(length + 1);
	if (devargs =3D=3D NULL)
		return -ENOMEM;
	snprintf(devargs, length + 1, "%s:%s,%s", busname, devname, drvargs);

Any preference?