rng:

- implement a request queue for rng-random so multiple guest requests
   don't result in vq buffers getting forgotten
 - remove unused request cancellation code
 - a VM with multiple vq buffers, when migrated, could get in a situation
   where not all buffers are handed back to the guest.  This is now
   fixed.
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Merge remote-tracking branch 'remotes/amit-virtio-rng/tags/rng-for-2.6-1' into staging

rng:
- implement a request queue for rng-random so multiple guest requests
  don't result in vq buffers getting forgotten
- remove unused request cancellation code
- a VM with multiple vq buffers, when migrated, could get in a situation
  where not all buffers are handed back to the guest.  This is now
  fixed.

# gpg: Signature made Thu 03 Mar 2016 12:18:54 GMT using RSA key ID 854083B6
# gpg: Good signature from "Amit Shah <amit@amitshah.net>"
# gpg:                 aka "Amit Shah <amit@kernel.org>"
# gpg:                 aka "Amit Shah <amitshah@gmx.net>"

* remotes/amit-virtio-rng/tags/rng-for-2.6-1:
  virtio-rng: ask for more data if queue is not fully drained
  rng: add request queue support to rng-random
  rng: move request queue cleanup from RngEgd to RngBackend
  rng: move request queue from RngEgd to RngBackend
  rng: remove the unused request cancellation code
  MAINTAINERS: Add an entry for the include/sysemu/rng*.h files

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

MAINTAINERS

@@ -921,6 +921,7 @@ M: Amit Shah <amit.shah@redhat.com>
 S: Supported
 F: hw/virtio/virtio-rng.c
 F: include/hw/virtio/virtio-rng.h
+F: include/sysemu/rng*.h
 F: backends/rng*.c
 
 nvme

backends/rng-egd.c

@@ -25,33 +25,12 @@ typedef struct RngEgd
 
     CharDriverState *chr;
     char *chr_name;
-
-    GSList *requests;
 } RngEgd;
 
-typedef struct RngRequest
+static void rng_egd_request_entropy(RngBackend *b, RngRequest *req)
-{
-    EntropyReceiveFunc *receive_entropy;
-    uint8_t *data;
-    void *opaque;
-    size_t offset;
-    size_t size;
-} RngRequest;
-
-static void rng_egd_request_entropy(RngBackend *b, size_t size,
-                                    EntropyReceiveFunc *receive_entropy,
-                                    void *opaque)
 {
     RngEgd *s = RNG_EGD(b);
-    RngRequest *req;
+    size_t size = req->size;
-
-    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);
 
     while (size > 0) {
         uint8_t header[2];
@@ -65,14 +44,6 @@ static void rng_egd_request_entropy(RngBackend *b, size_t size,
 
         size -= len;
     }
-
-    s->requests = g_slist_append(s->requests, req);
-}
-
-static void rng_egd_free_request(RngRequest *req)
-{
-    g_free(req->data);
-    g_free(req);
 }
 
 static int rng_egd_chr_can_read(void *opaque)
@@ -81,7 +52,7 @@ static int rng_egd_chr_can_read(void *opaque)
     GSList *i;
     int size = 0;
 
-    for (i = s->requests; i; i = i->next) {
+    for (i = s->parent.requests; i; i = i->next) {
         RngRequest *req = i->data;
         size += req->size - req->offset;
     }
@@ -94,8 +65,8 @@ static void rng_egd_chr_read(void *opaque, const uint8_t *buf, int size)
     RngEgd *s = RNG_EGD(opaque);
     size_t buf_offset = 0;
 
-    while (size > 0 && s->requests) {
+    while (size > 0 && s->parent.requests) {
-        RngRequest *req = s->requests->data;
+        RngRequest *req = s->parent.requests->data;
         int len = MIN(size, req->size - req->offset);
 
         memcpy(req->data + req->offset, buf + buf_offset, len);
@@ -104,38 +75,13 @@ static void rng_egd_chr_read(void *opaque, const uint8_t *buf, int size)
         size -= len;
 
         if (req->offset == req->size) {
-            s->requests = g_slist_remove_link(s->requests, s->requests);
-
             req->receive_entropy(req->opaque, req->data, req->size);
 
-            rng_egd_free_request(req);
+            rng_backend_finalize_request(&s->parent, req);
         }
     }
 }
 
-static void rng_egd_free_requests(RngEgd *s)
-{
-    GSList *i;
-
-    for (i = s->requests; i; i = i->next) {
-        rng_egd_free_request(i->data);
-    }
-
-    g_slist_free(s->requests);
-    s->requests = NULL;
-}
-
-static void rng_egd_cancel_requests(RngBackend *b)
-{
-    RngEgd *s = RNG_EGD(b);
-
-    /* We simply delete the list of pending requests.  If there is data in the 
-     * queue waiting to be read, this is okay, because there will always be
-     * more data than we requested originally
-     */
-    rng_egd_free_requests(s);
-}
-
 static void rng_egd_opened(RngBackend *b, Error **errp)
 {
     RngEgd *s = RNG_EGD(b);
@@ -204,8 +150,6 @@ static void rng_egd_finalize(Object *obj)
     }
 
     g_free(s->chr_name);
-
-    rng_egd_free_requests(s);
 }
 
 static void rng_egd_class_init(ObjectClass *klass, void *data)
@@ -213,7 +157,6 @@ static void rng_egd_class_init(ObjectClass *klass, void *data)
     RngBackendClass *rbc = RNG_BACKEND_CLASS(klass);
 
     rbc->request_entropy = rng_egd_request_entropy;
-    rbc->cancel_requests = rng_egd_cancel_requests;
     rbc->opened = rng_egd_opened;
 }
 

backends/rng-random.c

@@ -22,10 +22,6 @@ struct RndRandom
 
     int fd;
     char *filename;
-
-    EntropyReceiveFunc *receive_func;
-    void *opaque;
-    size_t size;
 };
 
 /**
@@ -38,36 +34,35 @@ struct RndRandom
 static void entropy_available(void *opaque)
 {
     RndRandom *s = RNG_RANDOM(opaque);
-    uint8_t buffer[s->size];
-    ssize_t len;
 
-    len = read(s->fd, buffer, s->size);
+    while (s->parent.requests != NULL) {
-    if (len < 0 && errno == EAGAIN) {
+        RngRequest *req = s->parent.requests->data;
-        return;
+        ssize_t len;
+
+        len = read(s->fd, req->data, req->size);
+        if (len < 0 && errno == EAGAIN) {
+            return;
+        }
+        g_assert(len != -1);
+
+        req->receive_entropy(req->opaque, req->data, len);
+
+        rng_backend_finalize_request(&s->parent, req);
     }
-    g_assert(len != -1);
-
-    s->receive_func(s->opaque, buffer, len);
-    s->receive_func = NULL;
 
+    /* We've drained all requests, the fd handler can be reset. */
     qemu_set_fd_handler(s->fd, NULL, NULL, NULL);
 }
 
-static void rng_random_request_entropy(RngBackend *b, size_t size,
+static void rng_random_request_entropy(RngBackend *b, RngRequest *req)
-                                        EntropyReceiveFunc *receive_entropy,
-                                        void *opaque)
 {
     RndRandom *s = RNG_RANDOM(b);
 
-    if (s->receive_func) {
+    if (s->parent.requests == NULL) {
-        s->receive_func(s->opaque, NULL, 0);
+        /* If there are no pending requests yet, we need to
+         * install our fd handler. */
+        qemu_set_fd_handler(s->fd, entropy_available, NULL, s);
     }
-
-    s->receive_func = receive_entropy;
-    s->opaque = opaque;
-    s->size = size;
-
-    qemu_set_fd_handler(s->fd, entropy_available, NULL, s);
 }
 
 static void rng_random_opened(RngBackend *b, Error **errp)

backends/rng.c

@@ -20,18 +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));
-    }
-}
 
-void rng_backend_cancel_requests(RngBackend *s)
+        req->offset = 0;
-{
+        req->size = size;
-    RngBackendClass *k = RNG_BACKEND_GET_CLASS(s);
+        req->receive_entropy = receive_entropy;
+        req->opaque = opaque;
+        req->data = g_malloc(req->size);
 
-    if (k->cancel_requests) {
+        k->request_entropy(s, req);
-        k->cancel_requests(s);
+
+        s->requests = g_slist_append(s->requests, req);
     }
 }
 
@@ -73,6 +75,30 @@ static void rng_backend_prop_set_opened(Object *obj, bool value, Error **errp)
     s->opened = true;
 }
 
+static void rng_backend_free_request(RngRequest *req)
+{
+    g_free(req->data);
+    g_free(req);
+}
+
+static void rng_backend_free_requests(RngBackend *s)
+{
+    GSList *i;
+
+    for (i = s->requests; i; i = i->next) {
+        rng_backend_free_request(i->data);
+    }
+
+    g_slist_free(s->requests);
+    s->requests = NULL;
+}
+
+void rng_backend_finalize_request(RngBackend *s, RngRequest *req)
+{
+    s->requests = g_slist_remove(s->requests, req);
+    rng_backend_free_request(req);
+}
+
 static void rng_backend_init(Object *obj)
 {
     object_property_add_bool(obj, "opened",
@@ -81,6 +107,13 @@ static void rng_backend_init(Object *obj)
                              NULL);
 }
 
+static void rng_backend_finalize(Object *obj)
+{
+    RngBackend *s = RNG_BACKEND(obj);
+
+    rng_backend_free_requests(s);
+}
+
 static void rng_backend_class_init(ObjectClass *oc, void *data)
 {
     UserCreatableClass *ucc = USER_CREATABLE_CLASS(oc);
@@ -93,6 +126,7 @@ static const TypeInfo rng_backend_info = {
     .parent = TYPE_OBJECT,
     .instance_size = sizeof(RngBackend),
     .instance_init = rng_backend_init,
+    .instance_finalize = rng_backend_finalize,
     .class_size = sizeof(RngBackendClass),
     .class_init = rng_backend_class_init,
     .abstract = true,

hw/virtio/virtio-rng.c

@@ -69,6 +69,13 @@ static void chr_read(void *opaque, const void *buf, size_t size)
         g_free(elem);
     }
     virtio_notify(vdev, vrng->vq);
+
+    if (!virtio_queue_empty(vrng->vq)) {
+        /* If we didn't drain the queue, call virtio_rng_process
+         * to take care of asking for more data as appropriate.
+         */
+        virtio_rng_process(vrng);
+    }
 }
 
 static void virtio_rng_process(VirtIORNG *vrng)

include/sysemu/rng.h

@@ -24,6 +24,7 @@
 #define RNG_BACKEND_CLASS(klass) \
     OBJECT_CLASS_CHECK(RngBackendClass, (klass), TYPE_RNG_BACKEND)
 
+typedef struct RngRequest RngRequest;
 typedef struct RngBackendClass RngBackendClass;
 typedef struct RngBackend RngBackend;
 
@@ -31,13 +32,20 @@ typedef void (EntropyReceiveFunc)(void *opaque,
                                   const void *data,
                                   size_t size);
 
+struct RngRequest
+{
+    EntropyReceiveFunc *receive_entropy;
+    uint8_t *data;
+    void *opaque;
+    size_t offset;
+    size_t size;
+};
+
 struct RngBackendClass
 {
     ObjectClass parent_class;
 
-    void (*request_entropy)(RngBackend *s, size_t size,
+    void (*request_entropy)(RngBackend *s, RngRequest *req);
-                            EntropyReceiveFunc *receive_entropy, void *opaque);
-    void (*cancel_requests)(RngBackend *s);
 
     void (*opened)(RngBackend *s, Error **errp);
 };
@@ -48,8 +56,10 @@ struct RngBackend
 
     /*< protected >*/
     bool opened;
+    GSList *requests;
 };
 
+
 /**
  * rng_backend_request_entropy:
  * @s: the backend to request entropy from
@@ -70,12 +80,13 @@ void rng_backend_request_entropy(RngBackend *s, size_t size,
                                  void *opaque);
 
 /**
- * rng_backend_cancel_requests:
+ * rng_backend_free_request:
- * @s: the backend to cancel all pending requests in
+ * @s: the backend that created the request
+ * @req: the request to finalize
  *
- * Cancels all pending requests submitted by @rng_backend_request_entropy.  This
+ * Used by child rng backend classes to finalize requests once they've been
- * should be used by a device during reset or in preparation for live migration
+ * processed. The request is removed from the list of active requests and
- * to stop tracking any request.
+ * deleted.
  */
-void rng_backend_cancel_requests(RngBackend *s);
+void rng_backend_finalize_request(RngBackend *s, RngRequest *req);
 #endif