Re: [PATCH 2/3] KVM: Centralize slots_lock aquisition during KVM_CREATE_IRQCHIP
Takuya Yoshikawa <[email protected]> Thu, 16 Dec 2010 09:47:34 +0000
| Newsgroups | org.kernel.vger.kvm-ia64,org.kernel.vger.kvm |
|---|---|
| Message-ID | <[email protected]> |
(2010/12/16 18:34), Avi Kivity wrote: >>> Maybe we ought to move slots_lock acquisition to kvm_io_bus_register() and friends. >>> >> >> >> So it will move the lock acquisition to the opposite ( callee ) side than mine. >> At first, I tried to do that, but there are so many ... >> >> Anyway, your suggestion seems to be the best way if possible. >> >> >> One question: how about kvm_io_bus_[read|write] ? >> >> These are called from the emulator but I could not find where slots_lock >> are held though I can see the comments >> >> "kvm_io_bus_[read|write] - called under kvm->slots_lock" >> > > They're under srcu now, the comments are outdated. > > We used to have slots_lock be a rwsem, taken for read or write as necessary. Now we use srcu for read, and the slots_lock mutex + synchronize_srcu for write. > Ah, would you mind updating the comments? - or just removing outdated ones? I will reread these locking based on your answer! Thanks, Takuya