[Qemu-devel] [PATCH] qemu-img: fix in-flight count for qemu-img bench

[Paolo Bonzini <pbonzini@redhat.com>]

With aio=native (qemu-img bench -n) one or more requests can be completed
when a new request is submitted.  This in turn can cause bench_cb to
recurse before b->in_flight is updated.  The blk_aio_pwritev coroutines
are never freed, and qemu-img aborts.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 qemu-img.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/qemu-img.c b/qemu-img.c
index 6949b73..607dbe5 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -3559,6 +3559,9 @@ static void bench_cb(void *opaque, int ret)
     }
 
     while (b->n > b->in_flight && b->in_flight < b->nrreq) {
+        b->in_flight++;
+        b->offset += b->step;
+        b->offset %= b->image_size;
         if (b->write) {
             acb = blk_aio_pwritev(b->blk, b->offset, b->qiov, 0,
                                   bench_cb, b);
@@ -3570,9 +3573,6 @@ static void bench_cb(void *opaque, int ret)
             error_report("Failed to issue request");
             exit(EXIT_FAILURE);
         }
-        b->in_flight++;
-        b->offset += b->step;
-        b->offset %= b->image_size;
     }
 }
 
-- 
2.9.3