[Xen-devel] [PATCH V9 08/12] remus: implement the API to buffer/release packages

[Yang Hongyang <yanghy@xxxxxxxxxxxxxx>]

From: Shriram Rajagopalan <rshriram@xxxxxxxxx>

This patch implements two APIs:
1. netbuf_start_new_epoch()
   It marks a new epoch. The packages before this epoch will
   be flushed, and the packages after this epoch will be buffered.
   It will be called after the guest is suspended.
2. netbuf_release_prev_epoch()
   It flushes the buffered packages to client, and it will be
   called when a checkpoint finishes.

Signed-off-by: Shriram Rajagopalan <rshriram@xxxxxxxxx>
Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
Reviewed-by: Wen Congyang <wency@xxxxxxxxxxxxxx>
---
 tools/libxl/libxl_netbuffer.c | 57 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)

diff --git a/tools/libxl/libxl_netbuffer.c b/tools/libxl/libxl_netbuffer.c
index a5f2b9a..4b4bc9d 100644
--- a/tools/libxl/libxl_netbuffer.c
+++ b/tools/libxl/libxl_netbuffer.c
@@ -416,9 +416,66 @@ static int nic_teardown(libxl__remus_device *remus_dev,
     return REMUS_INPROGRESS;
 }
 
+/* The buffer_op's value, not the value passed to kernel */
+enum {
+    tc_buffer_start,
+    tc_buffer_release
+};
+
+static int remus_netbuf_op(libxl__remus_device_nic *remus_nic,
+                           libxl__remus_netbuf_state *netbuf_state,
+                           int buffer_op)
+{
+    int ret;
+
+    STATE_AO_GC(netbuf_state->ao);
+
+    if (buffer_op == tc_buffer_start)
+        ret = rtnl_qdisc_plug_buffer(remus_nic->qdisc);
+    else
+        ret = rtnl_qdisc_plug_release_one(remus_nic->qdisc);
+
+    if (!ret) {
+        ret = rtnl_qdisc_add(netbuf_state->nlsock,
+                             remus_nic->qdisc,
+                             NLM_F_REQUEST);
+        if (ret)
+            goto out;
+    }
+
+    return REMUS_OK;
+
+out:
+    LOG(ERROR, "Remus: cannot do netbuf op %s on %s:%s",
+        ((buffer_op == tc_buffer_start) ?
+        "start_new_epoch" : "release_prev_epoch"),
+        remus_nic->ifb, nl_geterror(ret));
+    return REMUS_FAIL;
+}
+
+static int netbuf_start_new_epoch(libxl__remus_device *remus_dev)
+{
+    libxl__remus_device_nic *remus_nic =
+        CONTAINER_OF(remus_dev, *remus_nic, remus_dev);
+    libxl__remus_netbuf_state *netbuf_state = remus_dev->dev_type->data;
+
+    return remus_netbuf_op(remus_nic, netbuf_state, tc_buffer_start);
+}
+
+static int netbuf_release_prev_epoch(libxl__remus_device *remus_dev)
+{
+    libxl__remus_device_nic *remus_nic =
+        CONTAINER_OF(remus_dev, *remus_nic, remus_dev);
+    libxl__remus_netbuf_state *netbuf_state = remus_dev->dev_type->data;
+
+    return remus_netbuf_op(remus_nic, netbuf_state, tc_buffer_release);
+}
+
 libxl__remus_device_type remus_device_nic = {
     .init = nic_init,
     .destroy = nic_destroy,
+    .postsuspend = netbuf_start_new_epoch,
+    .commit = netbuf_release_prev_epoch,
     .match = nic_match,
     .setup = nic_setup,
     .teardown = nic_teardown,
-- 
1.8.3.2


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