This is the first step in pushing down acquire/release, and will let
rfifolock drop the contention callback feature.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id:
1424449612-18215-3-git-send-email-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
bool progress;
int64_t timeout;
+ aio_context_acquire(ctx);
was_dispatching = ctx->dispatching;
progress = false;
timeout = blocking ? aio_compute_timeout(ctx) : 0;
/* wait until next event */
+ if (timeout) {
+ aio_context_release(ctx);
+ }
ret = qemu_poll_ns((GPollFD *)pollfds, npfd, timeout);
+ if (timeout) {
+ aio_context_acquire(ctx);
+ }
/* if we have any readable fds, dispatch event */
if (ret > 0) {
}
aio_set_dispatching(ctx, was_dispatching);
+ aio_context_release(ctx);
+
return progress;
}
int count;
int timeout;
+ aio_context_acquire(ctx);
have_select_revents = aio_prepare(ctx);
if (have_select_revents) {
blocking = false;
timeout = blocking
? qemu_timeout_ns_to_ms(aio_compute_timeout(ctx)) : 0;
+ if (timeout) {
+ aio_context_release(ctx);
+ }
ret = WaitForMultipleObjects(count, events, FALSE, timeout);
+ if (timeout) {
+ aio_context_acquire(ctx);
+ }
aio_set_dispatching(ctx, true);
if (first && aio_bh_poll(ctx)) {
progress |= timerlistgroup_run_timers(&ctx->tlg);
aio_set_dispatching(ctx, was_dispatching);
+ aio_context_release(ctx);
return progress;
}
void aio_context_unref(AioContext *ctx);
/* Take ownership of the AioContext. If the AioContext will be shared between
- * threads, a thread must have ownership when calling aio_poll().
+ * threads, and a thread does not want to be interrupted, it will have to
+ * take ownership around calls to aio_poll(). Otherwise, aio_poll()
+ * automatically takes care of calling aio_context_acquire and
+ * aio_context_release.
*
- * Note that multiple threads calling aio_poll() means timers, BHs, and
- * callbacks may be invoked from a different thread than they were registered
- * from. Therefore, code must use AioContext acquire/release or use
- * fine-grained synchronization to protect shared state if other threads will
- * be accessing it simultaneously.
+ * Access to timers and BHs from a thread that has not acquired AioContext
+ * is possible. Access to callbacks for now must be done while the AioContext
+ * is owned by the thread (FIXME).
*/
void aio_context_acquire(AioContext *ctx);