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

# gpg: Signature made Tue 21 Nov 2017 17:01:33 GMT
# gpg:                using RSA key 0xBDBE7B27C0DE3057
# gpg: Good signature from "Jeffrey Cody <jcody@redhat.com>"
# gpg:                 aka "Jeffrey Cody <jeff@codyprime.org>"
# gpg:                 aka "Jeffrey Cody <codyprime@gmail.com>"
# Primary key fingerprint: 9957 4B4D 3474 90E7 9D98  D624 BDBE 7B27 C0DE 3057

* remotes/cody/tags/block-pull-request:
  qemu-iotest: add test for blockjob coroutine race condition
  qemu-iotests: add option in common.qemu for mismatch only
  coroutine: abort if we try to schedule or enter a pending coroutine
  blockjob: do not allow coroutine double entry or entry-after-completion

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

1 files changed, 13 insertions, 0 deletions

diff --git a/util/async.c b/util/async.c
index 0e1bd8780a..4dd9d95a9e 100644
--- a/util/async.c
+++ b/util/async.c
@@ -388,6 +388,9 @@ static void co_schedule_bh_cb(void *opaque)
         QSLIST_REMOVE_HEAD(&straight, co_scheduled_next);
         trace_aio_co_schedule_bh_cb(ctx, co);
         aio_context_acquire(ctx);
+
+        /* Protected by write barrier in qemu_aio_coroutine_enter */
+        atomic_set(&co->scheduled, NULL);
         qemu_coroutine_enter(co);
         aio_context_release(ctx);
     }
@@ -438,6 +441,16 @@ fail:
 void aio_co_schedule(AioContext *ctx, Coroutine *co)
 {
     trace_aio_co_schedule(ctx, co);
+    const char *scheduled = atomic_cmpxchg(&co->scheduled, NULL,
+                                           __func__);
+
+    if (scheduled) {
+        fprintf(stderr,
+                "%s: Co-routine was already scheduled in '%s'\n",
+                __func__, scheduled);
+        abort();
+    }
+
     QSLIST_INSERT_HEAD_ATOMIC(&ctx->scheduled_coroutines,
                               co, co_scheduled_next);
     qemu_bh_schedule(ctx->co_schedule_bh);