NetBSD/sys/netmpls
ozaki-r fe6d427551 Avoid storing a pointer of an interface in a mbuf
Having a pointer of an interface in a mbuf isn't safe if we remove big
kernel locks; an interface object (ifnet) can be destroyed anytime in any
packet processing and accessing such object via a pointer is racy. Instead
we have to get an object from the interface collection (ifindex2ifnet) via
an interface index (if_index) that is stored to a mbuf instead of an
pointer.

The change provides two APIs: m_{get,put}_rcvif_psref that use psref(9)
for sleep-able critical sections and m_{get,put}_rcvif that use
pserialize(9) for other critical sections. The change also adds another
API called m_get_rcvif_NOMPSAFE, that is NOT MP-safe and for transition
moratorium, i.e., it is intended to be used for places where are not
planned to be MP-ified soon.

The change adds some overhead due to psref to performance sensitive paths,
however the overhead is not serious, 2% down at worst.

Proposed on tech-kern and tech-net.
2016-06-10 13:31:43 +00:00
..
Makefile
files.netmpls
mpls.h
mpls_proto.c sprinkle _KERNEL_OPT 2015-08-24 22:21:26 +00:00
mpls_ttl.c Avoid storing a pointer of an interface in a mbuf 2016-06-10 13:31:43 +00:00
mpls_var.h sprinkle _KERNEL_OPT 2015-08-24 22:21:26 +00:00