Change 4787572d0580 made if_alloc_domain() never fail, then also do the
wrappers if_alloc(), if_alloc_dev(), and if_gethandle().

No functional change intended.

Reviewed by:	kp, imp, glebius, stevek
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D45740

Apply the following automated changes to try to eliminate
no-longer-needed sys/cdefs.h includes as well as now-empty
blank lines in a row.

Remove /^#if.*\n#endif.*\n#include\s+<sys/cdefs.h>.*\n/
Remove /\n+#include\s+<sys/cdefs.h>.*\n+#if.*\n#endif.*\n+/
Remove /\n+#if.*\n#endif.*\n+/
Remove /^#if.*\n#endif.*\n/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/types.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/param.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/capsicum.h>/

Sponsored by:		Netflix

Summary:
These came in the original DrvAPI commits in 2014, and are obsoleted by
bpf_mtap_if() and ether_bpf_mtap_if().  The `_if` suffix, rather than
prefix, conveys that it's operating on the bpf of the interface, instead
than the interface itself.

Reviewed by:	glebius
Sponsored by:	Juniper Networks, Inc.
Differential Revision: https://reviews.freebsd.org/D41146

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

r357614 added CTLFLAG_NEEDGIANT to make it easier to find nodes that are
still not MPSAFE (or already are but aren’t properly marked).
Use it in preparation for a general review of all nodes.

This is non-functional change that adds annotations to SYSCTL_NODE and
SYSCTL_PROC nodes using one of the soon-to-be-required flags.

Mark all obvious cases as MPSAFE.  All entries that haven't been marked
as MPSAFE before are by default marked as NEEDGIANT

Approved by:	kib (mentor, blanket)
Commented by:	kib, gallatin, melifaro
Differential Revision:	https://reviews.freebsd.org/D23718

switch over to opt-in instead of opt-out for epoch.

Instead of IFF_NEEDSEPOCH, provide IFF_KNOWSEPOCH. If driver marks
itself with IFF_KNOWSEPOCH, then ether_input() would not enter epoch
when processing its packets.

Now this will create recursive entrance in epoch in >90% network
drivers, but will guarantee safeness of the transition.

Mark several tested drivers as IFF_KNOWSEPOCH.

Reviewed by:		hselasky, jeff, bz, gallatin
Differential Revision:	https://reviews.freebsd.org/D23674

supposedly may call into ether_input() without network epoch.

They all need to be reviewed before 13.0-RELEASE.  Some may need
be fixed.  The flag is not planned to be used in the kernel for
a long time.

This allows replacing "sys/eventfilter.h" includes with "sys/_eventfilter.h"
in other header files (e.g., sys/{bus,conf,cpu}.h) and reduces header
pollution substantially.

EVENTHANDLER_DECLARE and EVENTHANDLER_LIST_DECLAREs were moved out of .c
files into appropriate headers (e.g., sys/proc.h, powernv/opal.h).

As a side effect of reduced header pollution, many .c files and headers no
longer contain needed definitions.  The remainder of the patch addresses
adding appropriate includes to fix those files.

LOCK_DEBUG and LOCK_FILE_LINE_ARG are moved to sys/_lock.h, as required by
sys/mutex.h since r326106 (but silently protected by header pollution prior
to this change).

No functional change (intended).  Of course, any out of tree modules that
relied on header pollution for sys/eventhandler.h, sys/lock.h, or
sys/mutex.h inclusion need to be fixed.  __FreeBSD_version has been bumped.

MFC after:	2 weeks