This is the misaligned-lock issue on the Alpha.
[ ... ]
Another solution is to change the <asm/bitops.h> to work with
non-word-aligned locks.
Heads up, take a look at other places within the kernel where objects
are used by bitops, they are all defined in such a way as to be word
aligned. This is not only a semantic issue, it is also a
performance/capability issue. [ I had to fix this in various places
at one point, linux/mm.h:mem_map_t->flags was one example ]
At least on the Alpha and Sparc64 processors, the atomic instructions
with which the bitops must be implemented, only allow word aligned
datums to be used.
So most of us would prefer that your driver defines bitop objects to
be word aligned thanks ;-)
Later,
David S. Miller
davem@dm.cobaltmicro.com