K 10
svn:author
V 3
kib
K 8
svn:date
V 27
2015-07-18T19:59:29.201956Z
K 7
svn:log
V 560
Further cleanup after r285607.

Remove useless release semantic for some stores to it_need.  For
stores where the release is needed, add a comment explaining why.

Fence after the atomic_cmpset() op on the it_need should be acquire
only, release is not needed (see above).  The combination of
atomic_cmpset() + fence_acq() is better expressed there as
atomic_cmpset_acq().

Use atomic_cmpset() for swi' ih_need read and clear.

Discussed with:	alc, bde
Reviewed by:	bde
Comments wording provided by:	bde
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks

END