On Fri, Aug 22, 2008 at 01:56:38PM -0700, akpm@xxxxxxxxxxxxxxxxxxxx wrote:
> Subject: Separate atomic_t declaration from asm/atomic.h into asm/atomic_def.h
> From: Huang Ying <ying.huang@xxxxxxxxx>
>
> asm/atomic.h contains both declaration and implementation of atomic_t. So
> there are some implementation related files included in asm/atomic.h. And
> atomic_t is a typedef. Combination of above makes it impossible to use
> atomic_t in files included by atomic.h. Such as atomic_t can not be used
> in linux/kernel.h on i386, because it is included by asm/atomic.h.
>
> It is reasonable to separate declaration from implementation. So a new
> file atomic_def.h is added for every architecture to accommodate the
> declaration of atomic_t.
Seems to me like all architectures could use:
+++ include/linux/atomic_type.h
+typedef struct { volatile int counter; } atomic_t;
+#ifdef CONFIG_64BIT
+typedef struct { volatile long counter; } atomic64_t;
+#endif
S390 has an __aligned__((4)) on theirs -- is this really necessary?
Doesn't s390 align ints to 4 bytes automatically? If it doesn't, it
shouldn't be harmful to add it to other architectures (iirc m68k only
requires 2-byte alignment for ints ... hmm, wonder if their atomic_t is
really atomic if, say, it cross a page boundary ...)
--
Matthew Wilcox Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours. We can't possibly take such
a retrograde step."
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