Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-request' into staging

# gpg: Signature made Wed 28 Sep 2016 19:15:22 BST
# gpg:                using RSA key 0x9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>"
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>"
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha/tags/block-pull-request:
  linux-aio: fix re-entrant completion processing
  test-coroutine: test qemu_coroutine_entered()
  coroutine: add qemu_coroutine_entered() function
  libqos: fix qvring_init()
  iothread: check iothread->ctx before aio_context_unref to avoid assertion
  aio-posix: avoid unnecessary aio_epoll_enabled() calls
  block: mirror: fix wrong comment of mirror_start

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

8 files changed, 78 insertions, 10 deletions

diff --git a/aio-posix.c b/aio-posix.c
index 43162a9f29..4ef34dd175 100644
--- a/aio-posix.c
+++ b/aio-posix.c
@@ -431,11 +431,13 @@ bool aio_poll(AioContext *ctx, bool blocking)
     assert(npfd == 0);
 
     /* fill pollfds */
-    QLIST_FOREACH(node, &ctx->aio_handlers, node) {
-        if (!node->deleted && node->pfd.events
-            && !aio_epoll_enabled(ctx)
-            && aio_node_check(ctx, node->is_external)) {
-            add_pollfd(node);
+
+    if (!aio_epoll_enabled(ctx)) {
+        QLIST_FOREACH(node, &ctx->aio_handlers, node) {
+            if (!node->deleted && node->pfd.events
+                && aio_node_check(ctx, node->is_external)) {
+                add_pollfd(node);
+            }
         }
     }
 
diff --git a/block/linux-aio.c b/block/linux-aio.c
index d4e19d444c..1685ec29a3 100644
--- a/block/linux-aio.c
+++ b/block/linux-aio.c
@@ -94,9 +94,12 @@ static void qemu_laio_process_completion(struct qemu_laiocb *laiocb)
 
     laiocb->ret = ret;
     if (laiocb->co) {
-        /* Jump and continue completion for foreign requests, don't do
-         * anything for current request, it will be completed shortly. */
-        if (laiocb->co != qemu_coroutine_self()) {
+        /* If the coroutine is already entered it must be in ioq_submit() and
+         * will notice laio->ret has been filled in when it eventually runs
+         * later.  Coroutines cannot be entered recursively so avoid doing
+         * that!
+         */
+        if (!qemu_coroutine_entered(laiocb->co)) {
             qemu_coroutine_enter(laiocb->co);
         }
     } else {
diff --git a/include/block/block_int.h b/include/block/block_int.h
index ef3c047cb3..3e79228eb0 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -722,7 +722,7 @@ void commit_active_start(const char *job_id, BlockDriverState *bs,
  * @errp: Error object.
  *
  * Start a mirroring operation on @bs.  Clusters that are allocated
- * in @bs will be written to @bs until the job is cancelled or
+ * in @bs will be written to @target until the job is cancelled or
  * manually completed.  At the end of a successful mirroring job,
  * @bs will be switched to read from @target.
  */
diff --git a/include/qemu/coroutine.h b/include/qemu/coroutine.h
index 29a20782f0..e6a60d55fd 100644
--- a/include/qemu/coroutine.h
+++ b/include/qemu/coroutine.h
@@ -92,6 +92,19 @@ Coroutine *coroutine_fn qemu_coroutine_self(void);
  */
 bool qemu_in_coroutine(void);
 
+/**
+ * Return true if the coroutine is currently entered
+ *
+ * A coroutine is "entered" if it has not yielded from the current
+ * qemu_coroutine_enter() call used to run it.  This does not mean that the
+ * coroutine is currently executing code since it may have transferred control
+ * to another coroutine using qemu_coroutine_enter().
+ *
+ * When several coroutines enter each other there may be no way to know which
+ * ones have already been entered.  In such situations this function can be
+ * used to avoid recursively entering coroutines.
+ */
+bool qemu_coroutine_entered(Coroutine *co);
 
 
 /**
diff --git a/iothread.c b/iothread.c
index fb08a60b4b..fbeb8deb38 100644
--- a/iothread.c
+++ b/iothread.c
@@ -75,6 +75,9 @@ static void iothread_instance_finalize(Object *obj)
     iothread_stop(obj, NULL);
     qemu_cond_destroy(&iothread->init_done_cond);
     qemu_mutex_destroy(&iothread->init_done_lock);
+    if (!iothread->ctx) {
+        return;
+    }
     aio_context_unref(iothread->ctx);
 }
 
diff --git a/tests/libqos/virtio.c b/tests/libqos/virtio.c
index 37ff860c16..105bccecaa 100644
--- a/tests/libqos/virtio.c
+++ b/tests/libqos/virtio.c
@@ -147,7 +147,7 @@ void qvring_init(const QGuestAllocator *alloc, QVirtQueue *vq, uint64_t addr)
 
     for (i = 0; i < vq->size - 1; i++) {
         /* vq->desc[i].addr */
-        writew(vq->desc + (16 * i), 0);
+        writeq(vq->desc + (16 * i), 0);
         /* vq->desc[i].next */
         writew(vq->desc + (16 * i) + 14, i + 1);
     }
diff --git a/tests/test-coroutine.c b/tests/test-coroutine.c
index 6431dd6d7c..abd97c23c1 100644
--- a/tests/test-coroutine.c
+++ b/tests/test-coroutine.c
@@ -53,6 +53,47 @@ static void test_self(void)
 }
 
 /*
+ * Check that qemu_coroutine_entered() works
+ */
+
+static void coroutine_fn verify_entered_step_2(void *opaque)
+{
+    Coroutine *caller = (Coroutine *)opaque;
+
+    g_assert(qemu_coroutine_entered(caller));
+    g_assert(qemu_coroutine_entered(qemu_coroutine_self()));
+    qemu_coroutine_yield();
+
+    /* Once more to check it still works after yielding */
+    g_assert(qemu_coroutine_entered(caller));
+    g_assert(qemu_coroutine_entered(qemu_coroutine_self()));
+    qemu_coroutine_yield();
+}
+
+static void coroutine_fn verify_entered_step_1(void *opaque)
+{
+    Coroutine *self = qemu_coroutine_self();
+    Coroutine *coroutine;
+
+    g_assert(qemu_coroutine_entered(self));
+
+    coroutine = qemu_coroutine_create(verify_entered_step_2, self);
+    g_assert(!qemu_coroutine_entered(coroutine));
+    qemu_coroutine_enter(coroutine);
+    g_assert(!qemu_coroutine_entered(coroutine));
+    qemu_coroutine_enter(coroutine);
+}
+
+static void test_entered(void)
+{
+    Coroutine *coroutine;
+
+    coroutine = qemu_coroutine_create(verify_entered_step_1, NULL);
+    g_assert(!qemu_coroutine_entered(coroutine));
+    qemu_coroutine_enter(coroutine);
+}
+
+/*
  * Check that coroutines may nest multiple levels
  */
 
@@ -389,6 +430,7 @@ int main(int argc, char **argv)
     g_test_add_func("/basic/yield", test_yield);
     g_test_add_func("/basic/nesting", test_nesting);
     g_test_add_func("/basic/self", test_self);
+    g_test_add_func("/basic/entered", test_entered);
     g_test_add_func("/basic/in_coroutine", test_in_coroutine);
     g_test_add_func("/basic/order", test_order);
     if (g_test_perf()) {
diff --git a/util/qemu-coroutine.c b/util/qemu-coroutine.c
index 3cbf225487..737bffa984 100644
--- a/util/qemu-coroutine.c
+++ b/util/qemu-coroutine.c
@@ -146,3 +146,8 @@ void coroutine_fn qemu_coroutine_yield(void)
     self->caller = NULL;
     qemu_coroutine_switch(self, to, COROUTINE_YIELD);
 }
+
+bool qemu_coroutine_entered(Coroutine *co)
+{
+    return co->caller;
+}