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Date: Thu, 4 Oct 2018 13:51:31 +0200
From: =?iso-8859-1?Q?Ga=EBtan?= Rivet <gaetan.rivet@6wind.com>
To: Thomas Monjalon <thomas@monjalon.net>
Cc: dev@dpdk.org, ophirmu@mellanox.com, qi.z.zhang@intel.com,
ferruh.yigit@intel.com, ktraynor@redhat.com
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Subject: Re: [dpdk-dev] [PATCH v5 5/5] eal: simplify parameters of hotplug
functions
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On Thu, Oct 04, 2018 at 01:46:54PM +0200, Thomas Monjalon wrote:
> 04/10/2018 11:44, Gaëtan 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)
> > >
> > > 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 = NULL;
> > > + int size, length = -1;
> > >
> > > - bus = rte_bus_find_by_name(busname);
> > > - if (bus == NULL) {
> > > - RTE_LOG(ERR, EAL, "Cannot find bus (%s)\n", busname);
> > > - return -ENOENT;
> > > - }
> > > + do { /* 2 iterations: first is to know string length */
> > > + size = length + 1;
> > > + length = snprintf(devargs, size, "%s:%s,%s", busname, devname, drvargs);
> > > + if (length >= size)
> > > + devargs = malloc(length + 1);
> > > + if (devargs == NULL)
> > > + return -ENOMEM;
> > > + } while (size == 0);
> >
> > 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.
> >
> > You should remove this loop, which then allow removing size, and forces using
> > 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 = snprintf(devargs, 0, "%s:%s,%s", busname, devname, drvargs);
> if (length < 0)
> return -EINVAL;
> devargs = malloc(length + 1);
> if (devargs == NULL)
> return -ENOMEM;
> snprintf(devargs, length + 1, "%s:%s,%s", busname, devname, drvargs);
>
> Any preference?
>
>
Yes, the second is cleaner IMO.
--
Gaëtan Rivet
6WIND