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, 14 insertions, 0 deletions

diff --git a/util/qemu-coroutine.c b/util/qemu-coroutine.c
index d6095c1d5a..9eff7fd450 100644
--- a/util/qemu-coroutine.c
+++ b/util/qemu-coroutine.c
@@ -107,8 +107,22 @@ void qemu_aio_coroutine_enter(AioContext *ctx, Coroutine *co)
     Coroutine *self = qemu_coroutine_self();
     CoroutineAction ret;
 
+    /* Cannot rely on the read barrier for co in aio_co_wake(), as there are
+     * callers outside of aio_co_wake() */
+    const char *scheduled = atomic_mb_read(&co->scheduled);
+
     trace_qemu_aio_coroutine_enter(ctx, self, co, co->entry_arg);
 
+    /* if the Coroutine has already been scheduled, entering it again will
+     * cause us to enter it twice, potentially even after the coroutine has
+     * been deleted */
+    if (scheduled) {
+        fprintf(stderr,
+                "%s: Co-routine was already scheduled in '%s'\n",
+                __func__, scheduled);
+        abort();
+    }
+
     if (co->caller) {
         fprintf(stderr, "Co-routine re-entered recursively\n");
         abort();