When being used in a multithreaded application there were problems
with memory pages/cachelines accessed by multiple threads/cpus at the
same time, while doing DMA transfers to/from those. To avoid such
situations this fix is creating a copy of the first and the last page
if it is not fully used. The data is copied from user-space into those
pages and results are copied back when the DDCB-request is
successfully finished.
Signed-off-by: NFrank Haverkamp <haver@linux.vnet.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>