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SubjectRe: arc_usr_cmpxchg and preemption
> On Thu, Mar 15, 2018 at 12:03 PM, Alexey Brodkin <> wrote:
> Here's a brief analysis:
> ARM: Looks like they got rid of that stuff in v4.4, see
> commit db695c0509d6 ("ARM: remove user cmpxchg syscall").
> M68K: That's even uglier implementation which is really asking for
> a facelift, look at sys_atomic_cmpxchg_32() here:
> MIPS: They do it via special sysmips syscall which among other things
> might handle MIPS_ATOMIC_SET with mips_atomic_set()
> I don't immediately see if there're others but really I'm not sure if it even worth trying to
> clean-up all that since efforts might be spent pointlessly.

xtensa is another one. We used to have a buggy implementation in
arch/xtensa/kernel/entry.S:fast_syscall_xtensa which we still keep
disabled by default, just in case somebody wanted backwards
compatibility. I don't think it's worth fixing.

-- Max

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