On Thu, Sep 01, 2016 at 01:04:26PM +0200, Manfred Spraul wrote: > If I understand it right, the rules are: > 1. spin_unlock_wait() must behave like spin_lock();spin_unlock(); > 2. spin_is_locked() must behave like spin_trylock() ? spin_unlock(),TRUE : > FALSE
I don't think spin_is_locked is as strong as all that. On arm64 and ppc, it's just smp_mb(); followed by a check on the lock value. It can't be used for the same sorts of inter-CPU synchronisation that spin_unlock_wait provides. > 3. the ACQUIRE during spin_lock applies to the lock load, not to the store. Correct. This is already documented for things like cmpxchg. > sem.c and nf_conntrack.c need only rule 1 now, but I would document the rest > as well, ok? > > I'll update the patches. Please CC me! Will
