Re: [libvirt] [PATCH 2/2 (v3)] util: fallback to ioctl(SIOCBRDELBR) if netlink RTM_DELLINK fails

On Wed, Aug 26, 2015 at 03:05:25PM -0400, Laine Stump wrote: > commit 09778e09 switched from using ioctl(SIOCBRDELBR) for bridge > device deletion to using a netlink RTM_DELLINK message, which is the > more modern way to delete a bridge (and also doesn't require the > bridge to be ~IFF_UP to succeed). However, although older kernels > (e.g. 2.6.32, in RHEL6/CentOS6) support deleting *some* link types > with RTM_NEWLINK, they don't support deleting bridges, and there is no > compile-time way to figure this out. > > This patch moves the body of the SIOCBRDELBR version of > virNetDevBridgeDelete() into a static function, calls the new function > from the original, and also calls the new function from the > RTM_DELLINK version if the RTM_DELLINK message generates an EOPNOTSUPP > error. Since RTM_DELLINK is done from the subordinate function > virNetlinkDelLink, which is also called for other purposes (deleting a > macvtap interface), a function pointer called "fallback" has been > added to the arglist of virNetlinkDelLink() - if that arg != NULL, the > provided function will be called when (and only when) RTM_DELLINK > fails with EOPNOTSUPP. > > Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1252780 (part 2) > --- > Another idea for doing this I came up with during review of the > others... > > src/util/virnetdevbridge.c | 41 > ++++++++++++++++++++++++++++++----------- > src/util/virnetdevmacvlan.c | 2 +- > src/util/virnetlink.c | 13 +++++++++++-- > src/util/virnetlink.h | 5 ++++- > 4 files changed, 46 insertions(+), 15 deletions(-) > > diff --git a/src/util/virnetdevbridge.c b/src/util/virnetdevbridge.c > index ae38901..3b06829 100644 > --- a/src/util/virnetdevbridge.c > +++ b/src/util/virnetdevbridge.c > @@ -558,20 +558,15 @@ int virNetDevBridgeCreate(const char *brname) > * > * Returns 0 in case of success or an errno code in case of failure. > */ > -#if defined(__linux__) && defined(HAVE_LIBNL) > -int virNetDevBridgeDelete(const char *brname) > -{ > - /* If netlink is available, use it, as it is successful at > - * deleting a bridge even if it is currently IFF_UP. > - */ > - return virNetlinkDelLink(brname); > -} > -#elif defined(HAVE_STRUCT_IFREQ) && defined(SIOCBRDELBR) > -int virNetDevBridgeDelete(const char *brname) > +#if defined(HAVE_STRUCT_IFREQ) && defined(SIOCBRDELBR) > +static int > +virNetDevBridgeDeleteWithIoctl(const char *brname) > { > int fd = -1; > int ret = -1; > > + ignore_value(virNetDevSetOnline(brname, false)); > + > if ((fd = virNetDevSetupControl(NULL, NULL)) < 0) > return -1; > > @@ -587,8 +582,32 @@ int virNetDevBridgeDelete(const char *brname) > VIR_FORCE_CLOSE(fd); > return ret; > } > +#endif > + > + > +#if defined(__linux__) && defined(HAVE_LIBNL) > +int > +virNetDevBridgeDelete(const char *brname) > +{ > + /* If netlink is available, use it, as it is successful at > + * deleting a bridge even if it is currently IFF_UP. fallback to > + * using ioctl(SIOCBRDELBR) if netlink fails with EOPNOTSUPP. > + */ > + return virNetlinkDelLink(brname, virNetDevBridgeDeleteWithIoctl); You're passing DeleteWithIoctl here, but that was defined only if defined(HAVE_STRUCT_IFREQ) && defined(SIOCBRDELBR), does it mean that if you have libnl on linux, you also have those two? If not, then I suggest adding check for HAVE_STRUCT_IFREQ && SIOCBRDELBR definitions atop this function definition as well, just to make sure we don't run into similar problems later on with some weird distribution/custom builds/versions. No need to resend, this is just a hint before pushing.