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iothread: release AioContext around aio_poll

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This is the first step towards having fine-grained critical sections in
dataplane threads, which will resolve lock ordering problems between
address_space_* functions (which need the BQL when doing MMIO, even
after we complete RCU-based dispatch) and the AioContext.

Because AioContext does not use contention callbacks anymore, the
unit test has to be changed.

Previously applied as a0710f7995 and
then reverted.

Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1477565348-5458-19-git-send-email-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
This commit is contained in:
Paolo Bonzini 2016-10-27 12:49:06 +02:00 • committed by Fam Zheng
parent c9d1a56174
commit 65c1b5b622
5 changed files with 41 additions and 55 deletions
Download patch file Download diff file Expand all files Collapse all files

22
tests/test-aio.c
View file

@ -100,6 +100,7 @@ static void event_ready_cb(EventNotifier *e)
typedef struct {
QemuMutex start_lock;
EventNotifier notifier;
bool thread_acquired;
} AcquireTestData;
@ -111,6 +112,11 @@ static void *test_acquire_thread(void *opaque)
qemu_mutex_lock(&data->start_lock);
qemu_mutex_unlock(&data->start_lock);
/* event_notifier_set might be called either before or after
* the main thread's call to poll(). The test case's outcome
* should be the same in either case.
*/
event_notifier_set(&data->notifier);
aio_context_acquire(ctx);
aio_context_release(ctx);
@ -125,20 +131,19 @@ static void set_event_notifier(AioContext *ctx, EventNotifier *notifier,
aio_set_event_notifier(ctx, notifier, false, handler);
}
static void dummy_notifier_read(EventNotifier *unused)
static void dummy_notifier_read(EventNotifier *n)
{
g_assert(false); /* should never be invoked */
event_notifier_test_and_clear(n);
}
static void test_acquire(void)
{
QemuThread thread;
EventNotifier notifier;
AcquireTestData data;
/* Dummy event notifier ensures aio_poll() will block */
event_notifier_init(&notifier, false);
set_event_notifier(ctx, &notifier, dummy_notifier_read);
event_notifier_init(&data.notifier, false);
set_event_notifier(ctx, &data.notifier, dummy_notifier_read);
g_assert(!aio_poll(ctx, false)); /* consume aio_notify() */
qemu_mutex_init(&data.start_lock);
@ -152,12 +157,13 @@ static void test_acquire(void)
/* Block in aio_poll(), let other thread kick us and acquire context */
aio_context_acquire(ctx);
qemu_mutex_unlock(&data.start_lock); /* let the thread run */
g_assert(!aio_poll(ctx, true));
g_assert(aio_poll(ctx, true));
g_assert(!data.thread_acquired);
aio_context_release(ctx);
qemu_thread_join(&thread);
set_event_notifier(ctx, &notifier, NULL);
event_notifier_cleanup(&notifier);
set_event_notifier(ctx, &data.notifier, NULL);
event_notifier_cleanup(&data.notifier);
g_assert(data.thread_acquired);
}