Re: [PATCH 02/11] locking, rwsem: drop explicit memory barriers

Michal Hocko
2016-04-04T09:03:36Z

On Fri 01-04-16 18:17:53, Davidlohr Bueso wrote:
[...]
> I think we can actually get rid of these files altogether. While I
> don't know the archs, it does not appear to be implementing any kind
> of workaround/optimization, which is obviously the whole purpose of
> defining per-arch rwsem internals, unless the redundant barriers are
> actually the purpose. So we could use the generic rwsem.h (which has
> optimizations and ACQUIRE/ RELEASE semantics, although nops for either
> sh or xtensa specifically). A first inspection shows that the code is
> in fact the same and continue to use 32bit rwsems.

OK, so this has passed my defconfig and allnoconfig for xtensa compile
test, allyesconfig has failed due to some unrelated reasons:
clk-qoriq.c:(.init.text+0x3ebd3): dangerous relocation: l32r: literal target out of range (try using text-section-literals): (.init.literal+0x17c60)
and zillions of similar... The same error is without the patch

I do not have a crosscompiler[1] for sh arch so I couldn't have tested
it but there shouldn't be any issues in principal. I will send two
patches as a follow up.

---
[1] https://www.kernel.org/pub/tools/crosstool/files/bin/x86_64/ doesn't
seem to have it.
--
Michal Hocko
SUSE Labs