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SubjectRe: [PATCH RFC LKMM 1/7] tools/memory-model: Add extra ordering for locks and remove it for ordinary release/acquire
> > Yes, it's true that implementing locks with atomic_cmpxchg_acquire 
> > should be correct on all existing architectures. And Paul has invited
> > a patch to modify the LKMM accordingly. If you feel that such a change
> > would be a useful enhancement to the LKMM's applicability, please write
> > it.
> Yes, please! That would be the "RmW" discussion which Andrea partially
> quoted earlier on, so getting that going independently from this patch
> sounds like a great idea to me.

That was indeed one of the proposal we discussed. As you recalled, that
proposal only covered RmWs load-acquire (and ordinary store-release); in
particular, I realized that comments such as:

"The atomic_cond_read_acquire() call above has provided the
necessary acquire semantics required for locking."

[from kernel/locking/qspinlock.c]

(for example) would still _not have "generic validity" _if we added the
above po-unlock-rf-lock-po term... (which, again, makes me somehow uncon-
fortable); Would to have _all_ the acquire be admissible for you?


> Cheers,
> Will

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