K 10
svn:author
V 7
glebius
K 8
svn:date
V 27
2019-10-29T17:36:06.076879Z
K 7
svn:log
V 1042
There is a long standing problem with multicast programming for NICs
and IPv6.  With IPv6 we may call if_addmulti() in context of processing
of an incoming packet.  Usually this is interrupt context.  While most
of the NIC drivers are able to reprogram multicast filters without
sleeping, some of them can't.  An example is e1000 family of drivers.
With iflib conversion the problem was somewhat hidden.  Iflib processes
packets in private taskqueue, so going to sleep doesn't trigger an
assertion.  However, the sleep would block operation of the driver and
following incoming packets would fill the ring and eventually would
start being dropped.  Enabling epoch for the full time of a packet
processing again started to trigger assertions for e1000.

Fix this problem once and for all using a general taskqueue to call
if_ioctl() method in all cases when if_addmulti() is called in a
non sleeping context.  Note that nobody cares about returned value.

Reviewed by:	hselasky, kib
Differential Revision:	  https://reviews.freebsd.org/D22154

END