Re: [libvirt] [PATCH] qemu: support live update of an interface's filter

Since we can't (currently) rely on the ability to provide blanket support for all possible network changes by calling the toplevel netdev hostside disconnect/connect functions (due to qemu only supporting a lockstep between initialization of host side and guest side of devices), in order to support live change of an interface's nwfilter we need to make a special purpose function to only call the nwfilter teardown and setup functions if the filter for an interface (or its parameters) changes. The pattern is nearly identical to that used to change the bridge that an interface is connected to. This patch was inspired by a request from Guido Winkelmann <guido(a)sagersystems.de&gt;, who tested an earlier version, and wrote an initial version of the nwfilterHashTable comparison function. I didn't spend any time trying to understand the contents of the nwfilterHashTable entries, or whether the comparison function is fully/correctly comparing the entries. I would appreciate if someone with better knowledge of that data structure (Stefan?) could check it out and provide suggestions. --- src/conf/nwfilter_params.c | 24 ++++++++++++++++++++ src/conf/nwfilter_params.h | 4 +++- src/libvirt_private.syms | 1 + src/qemu/qemu_hotplug.c | 55 +++++++++++++++++++++++++++++++++++++++++++--- 4 files changed, 80 insertions(+), 4 deletions(-) diff --git a/src/conf/nwfilter_params.c b/src/conf/nwfilter_params.c index 6dc4baa..e42a54c 100644 --- a/src/conf/nwfilter_params.c +++ b/src/conf/nwfilter_params.c @@ -764,6 +764,30 @@ err_exit: return -1; } +static int +virNWFilterHashTableCompare(const void *a, const void *b) +{ + /* need to return 0 if equal */ + return STRNEQ_NULLABLE(a, b);

+} + +bool +virNWFilterHashTableEqual(virNWFilterHashTablePtr a, + virNWFilterHashTablePtr b) +{ + if (!(a || b)) + return true; + if (!(a && b)) + return false;

+ if (a->nNames != b->nNames) + return false;

+ if (!(a->hashTable || b->hashTable)) + return true;

+ if (!(a->hashTable && b->hashTable)) + return false;

+ + return virHashEqual(a->hashTable, b->hashTable, virNWFilterHashTableCompare); +}