Re: [Qemu-devel] [PATCH 2/2] migration: Poison ramblock loops in migration

[Peter Xu]

On Wed, Jun 06, 2018 at 11:36:00AM +0800, Peter Xu wrote:
> On Tue, Jun 05, 2018 at 05:25:45PM +0100, Dr. David Alan Gilbert (git) wrote:
> > From: "Dr. David Alan Gilbert" <address@hidden>
> > 
> > The migration code should be using the
> >   RAMBLOCK_FOREACH_MIGRATABLE and qemu_ram_foreach_block_migratable
> > not the all-block versions;  poison them so that we can't accidentally
> > use them.
> > 
> > Signed-off-by: Dr. David Alan Gilbert <address@hidden>
> > ---
> >  include/exec/ramlist.h | 4 +++-
> >  migration/migration.h  | 3 +++
> >  migration/ram.c        | 4 +++-
> >  3 files changed, 9 insertions(+), 2 deletions(-)
> > 
> > diff --git a/include/exec/ramlist.h b/include/exec/ramlist.h
> > index 2e2ac6cb99..bc4faa1b00 100644
> > --- a/include/exec/ramlist.h
> > +++ b/include/exec/ramlist.h
> > @@ -56,8 +56,10 @@ typedef struct RAMList {
> >  extern RAMList ram_list;
> >  
> >  /* Should be holding either ram_list.mutex, or the RCU lock. */
> > -#define  RAMBLOCK_FOREACH(block)  \
> > +#define  INTERNAL_RAMBLOCK_FOREACH(block)  \
> >      QLIST_FOREACH_RCU(block, &ram_list.blocks, next)
> > +/* Never use the INTERNAL_ version except for defining other macros */
> > +#define RAMBLOCK_FOREACH(block) INTERNAL_RAMBLOCK_FOREACH(block)
> >  
> >  void qemu_mutex_lock_ramlist(void);
> >  void qemu_mutex_unlock_ramlist(void);
> > diff --git a/migration/migration.h b/migration/migration.h
> > index 5af57d616c..31d3ed12dc 100644
> > --- a/migration/migration.h
> > +++ b/migration/migration.h
> > @@ -284,4 +284,7 @@ void migrate_send_rp_resume_ack(MigrationIncomingState 
> > *mis, uint32_t value);
> >  void dirty_bitmap_mig_before_vm_start(void);
> >  void init_dirty_bitmap_incoming_migration(void);
> >  
> > +#define qemu_ram_foreach_block \
> > +  #warning "Use qemu_ram_foreach_block_migratable in migration code"
> > +
> >  #endif
> > diff --git a/migration/ram.c b/migration/ram.c
> > index a7807cea84..e0d19305ee 100644
> > --- a/migration/ram.c
> > +++ b/migration/ram.c
> > @@ -159,9 +159,11 @@ out:
> >  
> >  /* Should be holding either ram_list.mutex, or the RCU lock. */
> >  #define RAMBLOCK_FOREACH_MIGRATABLE(block)             \
> > -    RAMBLOCK_FOREACH(block)                            \
> > +    INTERNAL_RAMBLOCK_FOREACH(block)                   \
> >          if (!qemu_ram_is_migratable(block)) {} else
> >  
> > +#undef RAMBLOCK_FOREACH
> 
> This will only cover the ram.c file.  How about we move
> RAMBLOCK_FOREACH_MIGRATABLE() directly into migration.h then undef
> RAMBLOCK_FOREACH there?  Then since migration.h should be used in all
> the migration internal source files so the poisoned bit can be used in
> a broader aspect?

(I forgot to reply-all.... forwarding to the list)

> 
> Thanks,
> 
> > +
> >  static void ramblock_recv_map_init(void)
> >  {
> >      RAMBlock *rb;
> > -- 
> > 2.17.0
> > 
> 
> -- 
> Peter Xu

-- 
Peter Xu