On Wed, 2010-08-11 at 16:41 +1000, Paul Mackerras wrote: > On Wed, Aug 11, 2010 at 03:20:05PM +1000, Anton Blanchard wrote: > > > All recent POWER CPUs check the address before letting the stcx succeed > > so we can create a CPU feature and nop it out. As Ben suggested, we can > > only do this in our syscall path because there is a remote possibility > > some kernel code gets interrupted by an exception that ends up operating > > on the same cacheline. > > Nice... Just one nit, and that is that I think we now need a dummy > stcx in the context switch code so there is no possibility of getting > from one user context to another with a reservation still pending from > the first context. I guess our chances of getting through schedule() > without doing any atomics, bitops or spinlocks are pretty remote, but > nevertheless it might be as well to make sure.
Do we care ? IE. If we define that the moment you have done a syscall, the reservation state is undefined, we are clear here, don't you think ? Cheers, Ben. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
