Messages in this thread | | | From | Linus Torvalds <> | Date | Fri, 24 Mar 2017 12:20:37 -0700 | Subject | Re: locking/atomic: Introduce atomic_try_cmpxchg() |
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On Fri, Mar 24, 2017 at 12:16 PM, Andy Lutomirski <luto@kernel.org> wrote: >> >> Not to mention we cannot use the C11 atomics in kernel because we want >> to be able to runtime patch LOCK prefixes when only 1 CPU is available. > > Is this really a show-stopper? I bet that objtool could be persuaded > to emit a list of the locations of all those LOCK prefixes.
I doubt it's a show-stopper, if only because nobody cares about UP any more. Not even the embedded world does.
That said, I'm not convinced that there will ever really be a reason for the kernel to use the C11 atomics. They just aren't any better than what we can do ourselves.
The reason for C11 atomics is "portably good atomics". We use "architecture-specific good atomics" instead, and are willing to maintain that. We will *have* to maintain that in the forseeable future anyway, for legacy compiler issues.
So any C11 atomics use by the kernel is realistically at least a decade away if it *ever* happens.
Don't even worry about it. Planning decades ahead for some detail like that is stupid.
Linus
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