K 10
svn:author
V 3
imp
K 8
svn:date
V 27
2018-03-12T15:17:16.222056Z
K 7
svn:log
V 309
Tighten up periph lock to avoid some races

Make sure the periph lock is held around rmw access to softc data,
espeically flags, including work flags in iosched.
Add asserts for the periph lock where it should be held.

PR: 226510
Sponsored by: Netflix
Differential Review: https://reviews.freebsd.org/D14456

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