* Peter Xu (pet...@redhat.com) wrote:
> On Thu, Mar 23, 2017 at 09:45:23PM +0100, Juan Quintela wrote:
> > This are the last postcopy fields still at MigrationState. Once there
>
> s/This/These/
>
> > Move MigrationSrcPageRequest to ram.c and remove MigrationState
> > parameters where appropiate.
> >
> > Signed-off-by: Juan Quintela <quint...@redhat.com>
>
> Reviewed-by: Peter Xu <pet...@redhat.com>
>
> One question below though...
>
> [...]
>
> > @@ -1191,19 +1204,18 @@ static bool get_queued_page(RAMState *rs,
> > MigrationState *ms,
> > *
> > * It should be empty at the end anyway, but in error cases there may
> > * xbe some left.
> > - *
> > - * @ms: current migration state
> > */
> > -void flush_page_queue(MigrationState *ms)
> > +void flush_page_queue(void)
> > {
> > - struct MigrationSrcPageRequest *mspr, *next_mspr;
> > + struct RAMSrcPageRequest *mspr, *next_mspr;
> > + RAMState *rs = &ram_state;
> > /* This queue generally should be empty - but in the case of a failed
> > * migration might have some droppings in.
> > */
> > rcu_read_lock();
>
> Could I ask why we are taking the RCU read lock rather than the mutex
> here?
It's a good question whether we need anything at all.
flush_page_queue is called only from migrate_fd_cleanup.
migrate_fd_cleanup is called either from a backhalf, which I think has the bql,
or from a failure path in migrate_fd_connect.
migrate_fd_connect is called from migration_channel_connect and
rdma_start_outgoing_migration
which I think both end up at monitor commands so also in the bql.
So I think we can probably just lose the rcu_read_lock/unlock.
Dave
>
> > - QSIMPLEQ_FOREACH_SAFE(mspr, &ms->src_page_requests, next_req,
> > next_mspr) {
> > + QSIMPLEQ_FOREACH_SAFE(mspr, &rs->src_page_requests, next_req,
> > next_mspr) {
> > memory_region_unref(mspr->rb->mr);
> > - QSIMPLEQ_REMOVE_HEAD(&ms->src_page_requests, next_req);
> > + QSIMPLEQ_REMOVE_HEAD(&rs->src_page_requests, next_req);
> > g_free(mspr);
> > }
> > rcu_read_unlock();
>
> Thanks,
>
> -- peterx
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
