K 10
svn:author
V 3
zbb
K 8
svn:date
V 27
2015-07-08T13:52:59.320185Z
K 7
svn:log
V 382
Add memory barrier to bus_dmamap_sync()

On platforms which are fully IO-coherent, the map might be null.
We need to guarantee that all data is observable after the
sync operation is called. Add a memory barrier to ensure that on ARM.

Reviewed by:   andrew, kib
Obtained from: Semihalf
Sponsored by:  The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D3012

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