[06/12] savevm: introduce is_active method

Enable the creation of a method to tell migration if that section is
active and should be migrate.  We use it for blk-migration, that is
normally not active.  We don't create the method for RAM, as setups
without RAM are very strange O:-)

Signed-off-by: Juan Quintela <quintela@redhat.com>
---
 block-migration.c |   13 ++++++-------
 savevm.c          |   15 +++++++++++++++
 vmstate.h         |    1 +
 3 files changed, 22 insertions(+), 7 deletions(-)

On 6/28/2012 11:22 PM, Juan Quintela wrote:
> Enable the creation of a method to tell migration if that section is
> active and should be migrate.  We use it for blk-migration, that is
> normally not active.  We don't create the method for RAM, as setups
> without RAM are very strange O:-)
>
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> ---
>   block-migration.c |   13 ++++++-------
>   savevm.c          |   15 +++++++++++++++
>   vmstate.h         |    1 +
>   3 files changed, 22 insertions(+), 7 deletions(-)
>
> diff --git a/block-migration.c b/block-migration.c
> index cd8a8dd..6d37dc1 100644
> --- a/block-migration.c
> +++ b/block-migration.c
> @@ -548,13 +548,6 @@ static int block_save_live(QEMUFile *f, int stage, void *opaque)
>       DPRINTF("Enter save live stage %d submitted %d transferred %d\n",
>               stage, block_mig_state.submitted, block_mig_state.transferred);
>
> -
> -    if (block_mig_state.blk_enable != 1) {
> -        /* no need to migrate storage */
> -        qemu_put_be64(f, BLK_MIG_FLAG_EOS);
> -        return 1;
> -    }
> -
>       if (stage == 1) {
>           init_blk_migration(f);
>
> @@ -710,11 +703,17 @@ static void block_set_params(const MigrationParams *params, void *opaque)
>       block_mig_state.blk_enable |= params->shared;
>   }
>
> +static bool block_is_active(void *opaque)
> +{
> +    return block_mig_state.blk_enable == 1;
> +}
> +
>   SaveVMHandlers savevm_block_handlers = {
>       .set_params = block_set_params,
>       .save_live_state = block_save_live,
>       .load_state = block_load,
>       .cancel = block_migration_cancel,
> +    .is_active = block_is_active,
>   };
>
>   void blk_mig_init(void)
> diff --git a/savevm.c b/savevm.c
> index 888c5a2..afa0c9e 100644
> --- a/savevm.c
> +++ b/savevm.c
> @@ -1576,6 +1576,11 @@ int qemu_savevm_state_begin(QEMUFile *f,
>           if (!se->ops || !se->ops->save_live_state) {
>               continue;
>           }
> +        if (se->ops && se->ops->is_active) {
> +            if (!se->ops->is_active(se->opaque)) {

If we got here then we know for sure that se->ops != NULL,and then 
nested condition could be simplified to if (se->ops->is_active && 
!se->ops->is_active(se->opaque)). Same for qemu_savevm_state_iterate() 
amd qemu_savevm_state_complete()

> +                continue;
> +            }
> +        }
>           /* Section type */
>           qemu_put_byte(f, QEMU_VM_SECTION_START);
>           qemu_put_be32(f, se->section_id);
> @@ -1618,6 +1623,11 @@ int qemu_savevm_state_iterate(QEMUFile *f)
>           if (!se->ops || !se->ops->save_live_state) {
>               continue;
>           }
> +        if (se->ops && se->ops->is_active) {
> +            if (!se->ops->is_active(se->opaque)) {
> +                continue;
> +            }
> +        }
>           if (qemu_file_rate_limit(f)) {
>               return 0;
>           }
> @@ -1658,6 +1668,11 @@ int qemu_savevm_state_complete(QEMUFile *f)
>           if (!se->ops || !se->ops->save_live_state) {
>               continue;
>           }
> +        if (se->ops && se->ops->is_active) {
> +            if (!se->ops->is_active(se->opaque)) {
> +                continue;
> +            }
> +        }
>           trace_savevm_section_start();
>           /* Section type */
>           qemu_put_byte(f, QEMU_VM_SECTION_END);
> diff --git a/vmstate.h b/vmstate.h
> index 1dd42f5..96651a5 100644
> --- a/vmstate.h
> +++ b/vmstate.h
> @@ -35,6 +35,7 @@ typedef struct SaveVMHandlers {
>       int (*save_live_state)(QEMUFile *f, int stage, void *opaque);
>       void (*cancel)(void *opaque);
>       LoadStateHandler *load_state;
> +    bool (*is_active)(void *opaque);
>   } SaveVMHandlers;
>
>   int register_savevm(DeviceState *dev,
>

Igor Mitsyanko <i.mitsyanko@gmail.com> wrote:
> On 6/28/2012 11:22 PM, Juan Quintela wrote:
>> Enable the creation of a method to tell migration if that section is
>> active and should be migrate.  We use it for blk-migration, that is
>> normally not active.  We don't create the method for RAM, as setups
>> without RAM are very strange O:-)
>>
>> Signed-off-by: Juan Quintela <quintela@redhat.com>
>> @@ -1576,6 +1576,11 @@ int qemu_savevm_state_begin(QEMUFile *f,
>>           if (!se->ops || !se->ops->save_live_state) {
>>               continue;
>>           }
>> +        if (se->ops && se->ops->is_active) {
>> +            if (!se->ops->is_active(se->opaque)) {
>
> If we got here then we know for sure that se->ops != NULL,and then
> nested condition could be simplified to if (se->ops->is_active &&
> !se->ops->is_active(se->opaque)). Same for qemu_savevm_state_iterate()
> amd qemu_savevm_state_complete()

I tried to maintain consistency with the previous test, i.e. all have
the same structure.  I am still not sure which one is better :-()

The approach that I did put the things in the same order, yours, remove
two lines and one && operand.

Will think about that one, thanks.

Later, Juan.