eeac5c142b
It seems that the occasional data corruption observed with the tg3 driver wasn't due to missing barriers after all, but rather seems to be due to the DART (= IOMMU) in the U4 northbridge reading stale IOMMU table entries from memory due to a race. This fixes it by making the CPU read the entry back from memory before using it. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@samba.org>