Date: Sun, 17 May 2015 02:14:30 -0400 From: Rich Felker <dalias@...c.org> To: musl@...ts.openwall.com Subject: Re: Deduplicating atomics written in terms of CAS On Sun, May 17, 2015 at 09:00:15AM +0300, Alexander Monakov wrote: > It seems the prototype of a_cas_p has changed: > > void *a_cas_p(volatile void **p, void *t, void *s) > > Shouldn't the type of the first argument be 'void * volatile *'? Yes, thanks for catching it. BTW changing from the current void* to this will probably expose minor aliasing bugs I want to fix. I might just change all pointers used with a_cas_p to uintptr_t, and have a_cas_p work on uintptr_t, and force the code using them to cast back and forth to real pointers. Alternatively we could try to get rid of a_cas_p entirely. I'd like to trim down both the set of atomic primitives we're using and the number of direct uses of atomics (versus higher-level primitives like locks). Some candidates to remove: - a_cas_p - a_or_l (only used in sigaction; could be replaced by a_or) - a_and (not used at all) - a_and_64/a_or_64 (malloc only; these are misnamed too) Actually a_cas_p is the hardest to remove; while none of the users of it are performance-critical themselves, they are using it as a means of avoiding locking where the consumer of the data being written can't or doesn't want to require a lock. Rich
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