* Keir Fraser <Keir.Fraser@xxxxxxxxxxxxx> wrote: > On 16/3/07 08:54, "Ingo Molnar" <mingo@xxxxxxx> wrote: > > >> + prod = intf->in_prod; > >> + mb(); > >> + BUG_ON((prod - cons) > sizeof(intf->in)); > > > > such mb()'s are typically a sign of "i have no clear idea what SMP > > serialization rules apply here, but something is needed because > > otherwise it breaks" ? > > These mb()'s are pretty standard for lock-free producer/consumer > rings. Write descriptor /then/ write the updated producer. Read the > producer /then/ read any descriptors revealed by this new producer > value. then use rmb()/wmb(). Rarely does a ring protocol truly need mb(). Ingo _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxx https://lists.osdl.org/mailman/listinfo/virtualization
