On Wed, Sep 4, 2013 at 3:58 PM, Paolo Bonzini <pbonz...@redhat.com> wrote:
>
> > @@ -1323,23 +1325,21 @@ static RAMBlock *qemu_get_ram_block(ram_addr_t
addr)
> > {
> > RAMBlock *block;
> >
> > - /* The list is protected by the iothread lock here. */
> > + /* This assumes the iothread lock is taken here too. */
> > +
> > block = ram_list.mru_block;
> > if (block && addr - block->offset < block->length) {
> > - goto found;
> > + return block;
> > }
> > - QTAILQ_FOREACH(block, &ram_list.blocks, next) {
> > + QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
> > if (addr - block->offset < block->length) {
> > - goto found;
> > + atomic_rcu_set(&ram_list.mru_block, block);
>
> I think this is not needed, block was already published into the block
> list. What is important is to order mru_block == NULL so that it
> happens before the node is removed. Which we don't do, but we can fix
> later.
I am thinking of writing some macros and possibly reorganizing the ram
globals into a struct so that we can update it by exchanging pointers
atomically. It seems to disjoint right and error-prone now that we are
making it rcu-enabled.
thanks!
Mike
