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. All our ring protocols (and we have a few) require memory barriers. Those that use our standard set of ring macros have the memory barriers hidden from view, but they're still there. -- Keir _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxx https://lists.osdl.org/mailman/listinfo/virtualization
