Re: [Qemu-devel] [V4 PATCH 2/5] net: announce self after vm start

[Paolo Bonzini <pbonzini@redhat.com>]

Il 13/03/2012 09:56, Jason Wang ha scritto:
> This patch moves qemu_announce_self() to vm_start() and add a new parameters to
> control whether sending gratuitous packet is needed. There are several reasons
> to do this:
> 
> - Gratuitous packet is also needed when we resume a stopped vm or successfully
>   load a state.
> - Sending gratuitous packets may be done through co-operation with guest, so
>   this work should be done after vm is started.
> 
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
>  gdbstub.c   |    2 +-
>  migration.c |    5 ++---
>  monitor.c   |    2 +-
>  qmp.c       |    2 +-
>  savevm.c    |    2 +-
>  sysemu.h    |    2 +-
>  vl.c        |    7 +++++--
>  7 files changed, 12 insertions(+), 10 deletions(-)
> 
> diff --git a/gdbstub.c b/gdbstub.c
> index ef95ac2..f4d22e5 100644
> --- a/gdbstub.c
> +++ b/gdbstub.c
> @@ -371,7 +371,7 @@ static inline void gdb_continue(GDBState *s)
>  #ifdef CONFIG_USER_ONLY
>      s->running_state = 1;
>  #else
> -    vm_start();
> +    vm_start(false);
>  #endif

Here we're switching from RUNSTATE_DEBUG.

>  }
>  
> diff --git a/migration.c b/migration.c
> index 00fa1e3..40332d2 100644
> --- a/migration.c
> +++ b/migration.c
> @@ -88,14 +88,13 @@ void process_incoming_migration(QEMUFile *f)
>          fprintf(stderr, "load of migration failed\n");
>          exit(0);
>      }
> -    qemu_announce_self();
>      DPRINTF("successfully loaded vm state\n");
>  
>      /* Make sure all file formats flush their mutable metadata */
>      bdrv_invalidate_cache_all();
>  
>      if (autostart) {
> -        vm_start();
> +        vm_start(true);

Here from RUN_STATE_INMIGRATE.

>      } else {
>          runstate_set(RUN_STATE_PRELAUNCH);
>      }
> @@ -274,7 +273,7 @@ static void migrate_fd_put_ready(void *opaque)
>          }
>          if (s->state != MIG_STATE_COMPLETED) {
>              if (old_vm_running) {
> -                vm_start();
> +                vm_start(false);

Here from RUN_STATE_FINISH_MIGRATE.

>              }
>          }
>      }
> diff --git a/monitor.c b/monitor.c
> index cbdfbad..0b63c11 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -2260,7 +2260,7 @@ static void do_loadvm(Monitor *mon, const QDict *qdict)
>      vm_stop(RUN_STATE_RESTORE_VM);
>  
>      if (load_vmstate(name) == 0 && saved_vm_running) {
> -        vm_start();
> +        vm_start(true);

Here from RUN_STATE_RESTORE_VM.

>      }
>  }
>  
> diff --git a/qmp.c b/qmp.c
> index a182b51..252c842 100644
> --- a/qmp.c
> +++ b/qmp.c
> @@ -160,7 +160,7 @@ void qmp_cont(Error **errp)
>          return;
>      }
>  
> -    vm_start();
> +    vm_start(true);

Here from RUN_STATE_PAUSED or RUN_STATE_PRELAUNCH.

This introduces a difference here with "qemu -S" + cont, and "qemu".
The former will send a gratuitous ARP, the latter won't.  Is this
desired/harmless/...?

>  }
>  
>  void qmp_system_wakeup(Error **errp)
> diff --git a/savevm.c b/savevm.c
> index 5b59826..82b9d3a 100644
> --- a/savevm.c
> +++ b/savevm.c
> @@ -2107,7 +2107,7 @@ void do_savevm(Monitor *mon, const QDict *qdict)
>  
>   the_end:
>      if (saved_vm_running)
> -        vm_start();
> +        vm_start(false);
>  }

This is RUN_STATE_SAVE_VM.

>  
>  int load_vmstate(const char *name)
> diff --git a/sysemu.h b/sysemu.h
> index 98118cc..787edd4 100644
> --- a/sysemu.h
> +++ b/sysemu.h
> @@ -34,7 +34,7 @@ void vm_state_notify(int running, RunState state);
>  #define VMRESET_SILENT   false
>  #define VMRESET_REPORT   true
>  
> -void vm_start(void);
> +void vm_start(bool announce);
>  void vm_stop(RunState state);
>  void vm_stop_force_state(RunState state);
>  
> diff --git a/vl.c b/vl.c
> index 65f11f2..4e04f82 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -1258,7 +1258,7 @@ void vm_state_notify(int running, RunState state)
>      }
>  }
>  
> -void vm_start(void)
> +void vm_start(bool announce)
>  {
>      if (!runstate_is_running()) {
>          cpu_enable_ticks();
> @@ -1266,6 +1266,9 @@ void vm_start(void)
>          vm_state_notify(1, RUN_STATE_RUNNING);
>          resume_all_vcpus();
>          monitor_protocol_event(QEVENT_RESUME, NULL);
> +        if (announce) {
> +            qemu_announce_self();
> +        }
>      }
>  }
>  
> @@ -3619,7 +3622,7 @@ int main(int argc, char **argv, char **envp)
>              exit(ret);
>          }
>      } else if (autostart) {
> -        vm_start();
> +        vm_start(false);
>      }

This is RUN_STATE_PRELAUNCH.

To some up, it seems like whether to send an announcement depends on the
previous runstate: it should be sent only for RUN_STATE_INMIGRATE,
RUN_STATE_RESTORE_VM and (new with your patch) RUN_STATE_PAUSED.  So
perhaps the new argument to vm_start is not needed.

Paolo

>  
>      os_setup_post();
> 
> 
>