Re: [PATCH] arm64: Implement 1-,2- byte smp_load_acquire and smp_store_release

[Linus Torvalds]

On Mon, Apr 20, 2015 at 8:45 AM, Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx> wrote:
>
> Commit 8053871d0f7f ("smp: Fix smp_call_function_single_async() locking")
> started to use smp_load_acquire() to load 2-bytes csd->flags.
> That crashes arm64 kernel during the boot.

Ahh. I don't disagree with your patch, but we should just make
csd->flags be an "int" regardless of this issue.

There is absolutely no reason to try to use 16-bit words. It doesn't
save us any space (alignment), and it's just a *bad* idea to depend on
any kind of atomicity of 16-bit entities. Bytes, yes. Words, yes. But
16-bit half-words? There's no point.

So I'll make it "unsigned int" instead of "u16".

But as said, the ARM64 patch definitely is a good idea regardless.

                          Linus
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