virtio-blk: embed VirtQueueElement in VirtIOBlockReq

The memory allocation between hw/block/virtio-blk.c,
hw/block/dataplane/virtio-blk.c, and hw/virtio/dataplane/vring.c is
messy.  Structs are allocated in different files than they are freed in.
This is risky and makes memory leaks easier.

Embed VirtQueueElement in VirtIOBlockReq to reduce the amount of memory
allocation we need to juggle.  This also makes vring.c and virtio.c
slightly more similar.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 22 insertions, 24 deletions

diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index b06a56d942..02cd6b059a 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -29,20 +29,18 @@
 #include "hw/virtio/virtio-bus.h"
 #include "hw/virtio/virtio-access.h"
 
-static VirtIOBlockReq *virtio_blk_alloc_request(VirtIOBlock *s)
+VirtIOBlockReq *virtio_blk_alloc_request(VirtIOBlock *s)
 {
     VirtIOBlockReq *req = g_slice_new(VirtIOBlockReq);
     req->dev = s;
     req->qiov.size = 0;
     req->next = NULL;
-    req->elem = g_slice_new(VirtQueueElement);
     return req;
 }
 
-static void virtio_blk_free_request(VirtIOBlockReq *req)
+void virtio_blk_free_request(VirtIOBlockReq *req)
 {
     if (req) {
-        g_slice_free(VirtQueueElement, req->elem);
         g_slice_free(VirtIOBlockReq, req);
     }
 }
@@ -56,7 +54,7 @@ static void virtio_blk_complete_request(VirtIOBlockReq *req,
     trace_virtio_blk_req_complete(req, status);
 
     stb_p(&req->in->status, status);
-    virtqueue_push(s->vq, req->elem, req->qiov.size + sizeof(*req->in));
+    virtqueue_push(s->vq, &req->elem, req->qiov.size + sizeof(*req->in));
     virtio_notify(vdev, s->vq);
 }
 
@@ -121,7 +119,7 @@ static VirtIOBlockReq *virtio_blk_get_request(VirtIOBlock *s)
 {
     VirtIOBlockReq *req = virtio_blk_alloc_request(s);
 
-    if (!virtqueue_pop(s->vq, req->elem)) {
+    if (!virtqueue_pop(s->vq, &req->elem)) {
         virtio_blk_free_request(req);
         return NULL;
     }
@@ -254,7 +252,7 @@ static void virtio_blk_handle_scsi(VirtIOBlockReq *req)
 {
     int status;
 
-    status = virtio_blk_handle_scsi_req(req->dev, req->elem);
+    status = virtio_blk_handle_scsi_req(req->dev, &req->elem);
     virtio_blk_req_complete(req, status);
     virtio_blk_free_request(req);
 }
@@ -351,12 +349,12 @@ static void virtio_blk_handle_read(VirtIOBlockReq *req)
 void virtio_blk_handle_request(VirtIOBlockReq *req, MultiReqBuffer *mrb)
 {
     uint32_t type;
-    struct iovec *in_iov = req->elem->in_sg;
-    struct iovec *iov = req->elem->out_sg;
-    unsigned in_num = req->elem->in_num;
-    unsigned out_num = req->elem->out_num;
+    struct iovec *in_iov = req->elem.in_sg;
+    struct iovec *iov = req->elem.out_sg;
+    unsigned in_num = req->elem.in_num;
+    unsigned out_num = req->elem.out_num;
 
-    if (req->elem->out_num < 1 || req->elem->in_num < 1) {
+    if (req->elem.out_num < 1 || req->elem.in_num < 1) {
         error_report("virtio-blk missing headers");
         exit(1);
     }
@@ -393,19 +391,19 @@ void virtio_blk_handle_request(VirtIOBlockReq *req, MultiReqBuffer *mrb)
          * NB: per existing s/n string convention the string is
          * terminated by '\0' only when shorter than buffer.
          */
-        strncpy(req->elem->in_sg[0].iov_base,
+        strncpy(req->elem.in_sg[0].iov_base,
                 s->blk.serial ? s->blk.serial : "",
-                MIN(req->elem->in_sg[0].iov_len, VIRTIO_BLK_ID_BYTES));
+                MIN(req->elem.in_sg[0].iov_len, VIRTIO_BLK_ID_BYTES));
         virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
         virtio_blk_free_request(req);
     } else if (type & VIRTIO_BLK_T_OUT) {
-        qemu_iovec_init_external(&req->qiov, &req->elem->out_sg[1],
-                                 req->elem->out_num - 1);
+        qemu_iovec_init_external(&req->qiov, &req->elem.out_sg[1],
+                                 req->elem.out_num - 1);
         virtio_blk_handle_write(req, mrb);
     } else if (type == VIRTIO_BLK_T_IN || type == VIRTIO_BLK_T_BARRIER) {
         /* VIRTIO_BLK_T_IN is 0, so we can't just & it. */
-        qemu_iovec_init_external(&req->qiov, &req->elem->in_sg[0],
-                                 req->elem->in_num - 1);
+        qemu_iovec_init_external(&req->qiov, &req->elem.in_sg[0],
+                                 req->elem.in_num - 1);
         virtio_blk_handle_read(req);
     } else {
         virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP);
@@ -629,7 +627,7 @@ static void virtio_blk_save_device(VirtIODevice *vdev, QEMUFile *f)
 
     while (req) {
         qemu_put_sbyte(f, 1);
-        qemu_put_buffer(f, (unsigned char *)req->elem,
+        qemu_put_buffer(f, (unsigned char *)&req->elem,
                         sizeof(VirtQueueElement));
         req = req->next;
     }
@@ -654,15 +652,15 @@ static int virtio_blk_load_device(VirtIODevice *vdev, QEMUFile *f,
 
     while (qemu_get_sbyte(f)) {
         VirtIOBlockReq *req = virtio_blk_alloc_request(s);
-        qemu_get_buffer(f, (unsigned char *)req->elem,
+        qemu_get_buffer(f, (unsigned char *)&req->elem,
                         sizeof(VirtQueueElement));
         req->next = s->rq;
         s->rq = req;
 
-        virtqueue_map_sg(req->elem->in_sg, req->elem->in_addr,
-            req->elem->in_num, 1);
-        virtqueue_map_sg(req->elem->out_sg, req->elem->out_addr,
-            req->elem->out_num, 0);
+        virtqueue_map_sg(req->elem.in_sg, req->elem.in_addr,
+            req->elem.in_num, 1);
+        virtqueue_map_sg(req->elem.out_sg, req->elem.out_addr,
+            req->elem.out_num, 0);
     }
 
     return 0;