This seems to have worked just fine so far on weakly-ordered
architectures, but I don't see anything that prevents the
reordering from:
store 1 to exit_request
store 1 to tcg_exit_req
load tcg_exit_req
store 0 to tcg_exit_req
load exit_request
store 0 to exit_request
store 1 to exit_request
store 1 to tcg_exit_req
to this:
store 1 to exit_request
store 1 to tcg_exit_req
load tcg_exit_req
load exit_request
store 1 to exit_request
store 1 to tcg_exit_req
store 0 to tcg_exit_req
store 0 to exit_request
therefore losing a request. It's possible that other memory barriers
(e.g. in rcu_read_unlock) are hiding it, but better safe than
sorry.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>