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authorPaolo Bonzini <pbonzini@redhat.com>2015-02-20 17:26:52 +0100
committerKevin Wolf <kwolf@redhat.com>2015-04-28 15:36:08 +0200
commita0710f7995f914e3044e5899bd8ff6c43c62f916 (patch)
treea6a63bb73444688e7994a4a40eef3a38607f9251
parent49110174f8835ec3d5ca7fc076ee1f51c18564fe (diff)
iothread: release iothread around aio_poll
This is the first step towards having fine-grained critical sections in dataplane threads, which resolves 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. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 1424449612-18215-4-git-send-email-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
-rw-r--r--async.c8
-rw-r--r--iothread.c11
-rw-r--r--tests/test-aio.c19
3 files changed, 14 insertions, 24 deletions
diff --git a/async.c b/async.c
index 77d080d6f5..46d9e639d7 100644
--- a/async.c
+++ b/async.c
@@ -280,12 +280,6 @@ static void aio_timerlist_notify(void *opaque)
aio_notify(opaque);
}
-static void aio_rfifolock_cb(void *opaque)
-{
- /* Kick owner thread in case they are blocked in aio_poll() */
- aio_notify(opaque);
-}
-
AioContext *aio_context_new(Error **errp)
{
int ret;
@@ -303,7 +297,7 @@ AioContext *aio_context_new(Error **errp)
event_notifier_test_and_clear);
ctx->thread_pool = NULL;
qemu_mutex_init(&ctx->bh_lock);
- rfifolock_init(&ctx->lock, aio_rfifolock_cb, ctx);
+ rfifolock_init(&ctx->lock, NULL, NULL);
timerlistgroup_init(&ctx->tlg, aio_timerlist_notify, ctx);
return ctx;
diff --git a/iothread.c b/iothread.c
index 342a23fcb0..a1f91099bc 100644
--- a/iothread.c
+++ b/iothread.c
@@ -31,21 +31,14 @@ typedef ObjectClass IOThreadClass;
static void *iothread_run(void *opaque)
{
IOThread *iothread = opaque;
- bool blocking;
qemu_mutex_lock(&iothread->init_done_lock);
iothread->thread_id = qemu_get_thread_id();
qemu_cond_signal(&iothread->init_done_cond);
qemu_mutex_unlock(&iothread->init_done_lock);
- while (!iothread->stopping) {
- aio_context_acquire(iothread->ctx);
- blocking = true;
- while (!iothread->stopping && aio_poll(iothread->ctx, blocking)) {
- /* Progress was made, keep going */
- blocking = false;
- }
- aio_context_release(iothread->ctx);
+ while (!atomic_read(&iothread->stopping)) {
+ aio_poll(iothread->ctx, true);
}
return NULL;
}
diff --git a/tests/test-aio.c b/tests/test-aio.c
index a7cb5c9915..4b0cb45d31 100644
--- a/tests/test-aio.c
+++ b/tests/test-aio.c
@@ -107,6 +107,7 @@ static void test_notify(void)
typedef struct {
QemuMutex start_lock;
+ EventNotifier notifier;
bool thread_acquired;
} AcquireTestData;
@@ -118,6 +119,8 @@ static void *test_acquire_thread(void *opaque)
qemu_mutex_lock(&data->start_lock);
qemu_mutex_unlock(&data->start_lock);
+ g_usleep(500000);
+ event_notifier_set(&data->notifier);
aio_context_acquire(ctx);
aio_context_release(ctx);
@@ -126,20 +129,19 @@ static void *test_acquire_thread(void *opaque)
return NULL;
}
-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);
- aio_set_event_notifier(ctx, &notifier, dummy_notifier_read);
+ event_notifier_init(&data.notifier, false);
+ aio_set_event_notifier(ctx, &data.notifier, dummy_notifier_read);
g_assert(!aio_poll(ctx, false)); /* consume aio_notify() */
qemu_mutex_init(&data.start_lock);
@@ -153,12 +155,13 @@ 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);
- aio_set_event_notifier(ctx, &notifier, NULL);
- event_notifier_cleanup(&notifier);
+ aio_set_event_notifier(ctx, &data.notifier, NULL);
+ event_notifier_cleanup(&data.notifier);
g_assert(data.thread_acquired);
}