K 10
svn:author
V 6
kevans
K 8
svn:date
V 27
2019-10-02T15:13:40.793327Z
K 7
svn:log
V 415
mips: fcmpset: do not spin on sc failure

For ll/sc architectures, atomic(9) allows failure modes where *old == val
due to write failure and callers should compensate for this. Do not retry on
failure, just leave 0 in ret and fail the operation if we couldn't sc it.
This lets the caller determine if it should retry or not.

Reviewed by:	kib
Looks ok:	imp
Differential Revision:	https://reviews.freebsd.org/D21836

END