aio_poll(ctx, true) will soon block when fd handlers have been set.
Previously aio_poll() would return early if all .io_flush() returned
false.  This means we need to check the equivalent of the .io_flush()
condition *before* calling aio_poll(ctx, true) to avoid deadlock.
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

We're already using them in several places, but __sync builtins are just
too ugly to type, and do not provide seqcst load/store operations.
Reviewed-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Now that each AioContext has a ThreadPool and the main loop AioContext
can be fetched with bdrv_get_aio_context(), we can eliminate the concept
of a global thread pool from thread-pool.c.

The submit functions must take a ThreadPool* argument.

block/raw-posix.c and block/raw-win32.c use
aio_get_thread_pool(bdrv_get_aio_context(bs)) to fetch the main loop's
ThreadPool.

tests/test-thread-pool.c must be updated to reflect the new
thread_pool_submit() function prototypes.
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

We need to eliminate calls to qemu_aio_flush() since the function is
being removed.  Most callers will use bdrv_drain_all() instead but
test-thread-pool.c is lower level.

Since the test uses the global AioContext we can loop on qemu_aio_wait()
to wait for aio and bh activity to complete.
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
Acked-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

The cancellation test is failing on the buildbots.  While the failure
merits a little more investigation to understand what is going on,
the logs show that the failure is not impacting the coverage
provided by the test.  Hence, loosen a bit the assertions in a
way that should let the test proceed and hopefully pass.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>