K 10
svn:author
V 3
mjg
K 8
svn:date
V 27
2019-11-30T16:46:19.581282Z
K 7
svn:log
V 367
devfs: introduce a per-dev lock to protect ->si_devsw

This allows bumping threadcount without taking the global devmtx lock.

In particular this eliminates contention on said lock while using bhyve
with multiple vms.

Reviewed by:	kib
Tested by:	markj
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D22548

END