Re: [Qemu-devel] [PATCH 14/42] migration: prepare to access s->state outside critical sections

[Stefan Hajnoczi]

On Fri, Feb 22, 2013 at 5:36 PM, Paolo Bonzini <address@hidden> wrote:
> Accessing s->state outside the big QEMU lock will simplify a bit the
> locking/unlocking of the iothread lock.
>
> We need to keep the lock in migrate_fd_error and migrate_fd_completed,
> however, because they call migrate_fd_cleanup.
>
> Reviewed-by: Orit Wasserman <address@hidden>
> Reviewed-by: Juan Quintela <address@hidden>
> Signed-off-by: Paolo Bonzini <address@hidden>
> ---
>  migration.c | 33 +++++++++++++++++++++------------
>  1 file changed, 21 insertions(+), 12 deletions(-)
>
> diff --git a/migration.c b/migration.c
> index b091532..b40755f 100644
> --- a/migration.c
> +++ b/migration.c
> @@ -279,19 +279,25 @@ static void migrate_fd_cleanup(MigrationState *s)
>      notifier_list_notify(&migration_state_notifiers, s);
>  }
>
> +static void migrate_finish_set_state(MigrationState *s, int new_state)
> +{
> +    if (__sync_val_compare_and_swap(&s->state, MIG_STATE_ACTIVE,

kraxel_rhel61's mingw build fails:

  LINK  i386-softmmu/qemu-system-i386.exe
../migration.o:migration.c:(.text+0x408): undefined reference to
`__sync_val_compare_and_swap_4'
../migration.o:migration.c:(.text+0x7af): undefined reference to
`__sync_val_compare_and_swap_4'
../migration.o:migration.c:(.text+0x827): undefined reference to
`__sync_val_compare_and_swap_4'

http://buildbot.b1-systems.de/qemu/builders/default_mingw32/builds/566/steps/compile/logs/stdio

The latest RHEL6 mingw gcc is version 4.4 but this buildslave is
RHEL6.1 so perhaps it's an older version that is missing the atomics
builtins?

Stefan