rng: add request queue support to rng-random

Requests are now created in the RngBackend parent class and the
code path is shared by both rng-egd and rng-random.

This commit fixes the rng-random implementation which processed
only one request at a time and simply discarded all but the most
recent one. In the guest this manifested as delayed completion
of reads from virtio-rng, i.e. a read was completed only after
another read was issued.

By switching rng-random to use the same request queue as rng-egd,
the unsafe stack-based allocation of the entropy buffer is
eliminated and replaced with g_malloc.

Signed-off-by: Ladi Prosek <lprosek@redhat.com>
Reviewed-by: Amit Shah <amit.shah@redhat.com>
Message-Id: <1456994238-9585-5-git-send-email-lprosek@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/backends/rng.c b/backends/rng.c
index 014cb9d0fe..277a41bb0f 100644
--- a/backends/rng.c
+++ b/backends/rng.c
@@ -20,9 +20,20 @@ void rng_backend_request_entropy(RngBackend *s, size_t size,
                                  void *opaque)
 {
     RngBackendClass *k = RNG_BACKEND_GET_CLASS(s);
+    RngRequest *req;
 
     if (k->request_entropy) {
-        k->request_entropy(s, size, receive_entropy, opaque);
+        req = g_malloc(sizeof(*req));
+
+        req->offset = 0;
+        req->size = size;
+        req->receive_entropy = receive_entropy;
+        req->opaque = opaque;
+        req->data = g_malloc(req->size);
+
+        k->request_entropy(s, req);
+
+        s->requests = g_slist_append(s->requests, req);
     }
 }