tree 36cc2ea403155751b9ca9fa29ad29f34854102cd
parent 5d5da114b39d3cf187a69dcf5eaca7eaf886c041
author Paolo Bonzini <pbonzini@redhat.com> 1401972838 +0200
committer Stefan Hajnoczi <stefanha@redhat.com> 1403512573 +0800

vl: allow other threads to do qemu_system_vmstop_request

There patch protects vmstop_requested with a lock and introduces
qemu_system_vmstop_request_prepare.

Together with the new call to qemu_vmstop_requested in vm_start,
qemu_system_vmstop_request_prepare avoids a race where the VM could remain
stopped even though the iostatus of a block device has already been set
(for example).

qemu_system_vmstop_request_prepare however also lets the caller thread
delay observation of the state change until it has itself communicated
that change to the user.  This delay avoids any possibility of a wrong
reordering of the BLOCK_IO_ERROR event and the subsequent STOP event.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>