[libvirt] [PATCH 2/3] lxc: Turn @veths into a string list in virLXCProcessStart

[Erik Skultety]

On Fri, Jul 27, 2018 at 02:34:41PM +0200, Michal Privoznik wrote:
> On 07/27/2018 10:37 AM, Erik Skultety wrote:
> > On Thu, Jul 26, 2018 at 05:36:28PM +0200, Michal Privoznik wrote:
> >> This way it will be easier to use autofree.
> >>
> >> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
> >> ---
> >>  src/lxc/lxc_process.c | 24 +++++++++---------------
> >>  1 file changed, 9 insertions(+), 15 deletions(-)
> >>
> >> diff --git a/src/lxc/lxc_process.c b/src/lxc/lxc_process.c
> >> index d021a890f7..3ac39d598c 100644
> >> --- a/src/lxc/lxc_process.c
> >> +++ b/src/lxc/lxc_process.c
> >> @@ -514,8 +514,7 @@ static int virLXCProcessSetupNamespaces(virConnectPtr conn,
> >>   * virLXCProcessSetupInterfaces:
> >>   * @conn: pointer to connection
> >>   * @def: pointer to virtual machine structure
> >> - * @nveths: number of interfaces
> >> - * @veths: interface names
> >> + * @veths: string list of interface names
> >>   *
> >>   * Sets up the container interfaces by creating the veth device pairs and
> >>   * attaching the parent end to the appropriate bridge.  The container end
> >> @@ -525,7 +524,6 @@ static int virLXCProcessSetupNamespaces(virConnectPtr conn,
> >>   */
> >>  static int virLXCProcessSetupInterfaces(virConnectPtr conn,
> >>                                          virDomainDefPtr def,
> >> -                                        size_t *nveths,
> >>                                          char ***veths)
> >>  {
> >>      int ret = -1;
> >> @@ -534,6 +532,8 @@ static int virLXCProcessSetupInterfaces(virConnectPtr conn,
> >>      virDomainNetDefPtr net;
> >>      virDomainNetType type;
> >>
> >> +    *veths = NULL;
> >> +
> >>      for (i = 0; i < def->nnets; i++) {
> >>          char *veth = NULL;
> >>          virNetDevBandwidthPtr actualBandwidth;
> >> @@ -549,9 +549,6 @@ static int virLXCProcessSetupInterfaces(virConnectPtr conn,
> >>          if (virDomainNetAllocateActualDevice(def, net) < 0)
> >>              goto cleanup;
> >>
> >> -        if (VIR_EXPAND_N(*veths, *nveths, 1) < 0)
> >> -            goto cleanup;
> >
> > Contrary to what I said in the previous patch, I hadn't realized we were
> > expanding a list by 1 in a loop before I looked at this patch. That is very
> > inefficient and we'll keep doing that. Now I'm biased towards tracking the size
> > of the list so that we can do VIR_EXPAND_N(*veths, 0, def->nnets) and then just
> > add new elements, of course that would require tweaking the virStringListAdd
> > more.
> >
>
> Hold on. I'm not quite sure I follow. Are you suggesting to pre-allocate
> the string list and ditch virStringListAdd completely? Something like
> this?

Yes, that's the idea. Originally, I didn't think dropping virStringListAdd would
be necessary, but it's clear from the snippet below that it would.

Erik

>
> diff --git i/src/lxc/lxc_process.c w/src/lxc/lxc_process.c
> index 6eef17d1ce..33c806630b 100644
> --- i/src/lxc/lxc_process.c
> +++ w/src/lxc/lxc_process.c
> @@ -532,7 +532,8 @@ static int virLXCProcessSetupInterfaces(virConnectPtr conn,
>      virDomainNetDefPtr net;
>      virDomainNetType type;
>
> -    *veths = NULL;
> +    if (VIR_ALLOC_N(*veths, def->nnets + 1) < 0)
> +        return -1;
>
>      for (i = 0; i < def->nnets; i++) {
>          char *veth = NULL;
> @@ -601,8 +602,7 @@ static int virLXCProcessSetupInterfaces(virConnectPtr conn,
>              }
>          }
>
> -        if (virStringListAdd(veths, veth) < 0)
> -            goto cleanup;
> +        (*veths)[i] = veth;
>
>          if (VIR_STRDUP(def->nets[i]->ifname_guest_actual, veth) < 0)
>              goto cleanup;
>
>
> Michal
>
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