In if_freemulti(), relax the paranoid KASSERT() on ifma->ifma_protospec.

This KASSERT() existed as a sanity check that upper layers in the network
stack (e.g. inet, inet6) had released their reference to the underlying
driver's multicast memberships (ifmultiaddr{}). However it assumes the
lifecycle of the driver membership corresponds to the lifecycle of the
network layer membership.

In the submitter's case, ieee80211_ioctl_updatemulti() attempts to
reprogram the (parent, physical) ifnet{} memberships in response
to a change in membership on the (child, virtual) VAP ifnet, using
a batched update mechanism. These updates happen independently from
the network layer, causing a "false negative" assertion failure.

There are possibly other use cases where this KASSERT() may be triggered
by other networking stack activity (e.g. where a nesting relationship
exists between multiple ifnet{} instances). This suggests that further
review of FreeBSD's approach to nested ifnet relationships is needed.

MFC after:	6 weeks
Submitted by:	adrian@

1 files changed, 0 insertions, 2 deletions

diff --git a/sys/net/if.c b/sys/net/if.c
index cef3dd35f6a9..d3d6ac917f8e 100644
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -2937,8 +2937,6 @@ if_freemulti(struct ifmultiaddr *ifma)
 
 	KASSERT(ifma->ifma_refcount == 0, ("if_freemulti: refcount %d",
 	    ifma->ifma_refcount));
-	KASSERT(ifma->ifma_protospec == NULL,
-	    ("if_freemulti: protospec not NULL"));
 
 	if (ifma->ifma_lladdr != NULL)
 		free(ifma->ifma_lladdr, M_IFMADDR);