On Thu, Oct 20, 2016 at 12:22 AM, Matt Turner <matts...@gmail.com> wrote: > On Wed, Oct 19, 2016 at 1:58 PM, Jan Ziak <0xe2.0x9a.0...@gmail.com> wrote: >> The current git code and the patched code are fully equivalent to each >> other. In the unpatched code RefCount is always protected by a mutex >> and the RefCount adjustment region protects just the RefCount (it >> doesn't protect anything else) - in the patched code RefCount is >> always adjusted via p_atomic*(). >> >> Because of this equivalence: If the new code contains a bug then the >> unpatched code must contain the same bug as well. > > That's all well and good, but it's not sufficient and not really how > we do things. To replace the mutexes around bufferobjs and texobjs > with atomics would take us *further* from working code.
The patch replaces mutexes around RefCounts with atomics on RefCounts. Any other data reachable from bufferobj/texobj pointers still needs to be protected by a mutex (or multiple mutexes if necessary). Rule: A refcount dropping to zero implies that the refcounted data (that is: data under the refcount) won't be accessed from the direction of the refcount. A refcount dropping to zero can (under certain circumstances) imply that the refcounted data no longer needs to be protected by a mutex. _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
