Virtualize if_edsc(4).


git-svn-id: svn+ssh://svn.freebsd.org/base/head@272572 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Change the UMA mutex into a rwlock

Acquire the lock in read mode when just needed to ensure the stability
of the keg list. The UMA lock may be held for a long time (relatively
speaking) in uma_reclaim() on machines with lots of zones/kegs. If the
uma_timeout() would fire during that period, subsequent callouts on that
CPU may be significantly delayed.

Reviewed by:	jhb


git-svn-id: svn+ssh://svn.freebsd.org/base/head@272573 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
seq_t needs to be visible to userspace

Pointy hat to:	mjg
Reported by: bz
X-MFC:	with r272567


git-svn-id: svn+ssh://svn.freebsd.org/base/head@272574 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f