Re: [GIT] Sparc

From: Linus Torvalds
Date: Tue Aug 17 2010 - 21:59:51 EST


Oh,
I noticed another thing:

In commit 86fa04b8742ac681d470786f55e2403ada0075b2 you fix the return
type, but you still have the wrong _argument_ type:

extern void atomic64_add(int, atomic64_t *);
extern void atomic64_sub(int, atomic64_t *);
extern long atomic64_add_ret(int, atomic64_t *);
extern long atomic64_sub_ret(int, atomic64_t *);

note how if somebody does

atomic64_add(0x100000000ull, &x)

sparc64 will get it wrong, because it will only take the low 32 bits
of the first argument, and add zero to the 64-bit counter.

Which is definitely not what the code intended, I think.

I merged your pull request, but you've got some fixing up to do,
methinks. I also really think you need to make your rwsem's use 64-bit
values on sparc64, because otherwise you can overflow the mmap_sem by
having more than 65536 threads doing page-faults (on 32-bit, having
more than 2**16 threads in one process is unlikely to work for other
reasons, like just pure stack usage, so we don't really care about the
32-bit case)

Linus
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