[Xen-devel] [PATCH V8 4/8] remus: implement the API to buffer/release packages

[Yang Hongyang <yanghy@xxxxxxxxxxxxxx>]

This patch implements two APIs:
1. libxl__remus_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. libxl__remus_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_internal.h    |  7 ++++++
 tools/libxl/libxl_netbuffer.c   | 52 +++++++++++++++++++++++++++++++++++++++++
 tools/libxl/libxl_nonetbuffer.c | 14 +++++++++++
 3 files changed, 73 insertions(+)

diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index a6e5cff..1357f2d 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -2465,6 +2465,13 @@ _hidden void libxl__remus_teardown_done(libxl__egc *egc,
 _hidden void libxl__remus_netbuf_teardown(libxl__egc *egc,
                                           libxl__domain_suspend_state *dss);
 
+_hidden int
+libxl__remus_netbuf_start_new_epoch(libxl__gc *gc, uint32_t domid,
+                                    libxl__remus_state *remus_state);
+_hidden int
+libxl__remus_netbuf_release_prev_epoch(libxl__gc *gc, uint32_t domid,
+                                       libxl__remus_state *remus_state);
+
 struct libxl__domain_suspend_state {
     /* set by caller of libxl__domain_suspend */
     libxl__ao *ao;
diff --git a/tools/libxl/libxl_netbuffer.c b/tools/libxl/libxl_netbuffer.c
index 865cbb2..22fffec 100644
--- a/tools/libxl/libxl_netbuffer.c
+++ b/tools/libxl/libxl_netbuffer.c
@@ -509,6 +509,58 @@ void libxl__remus_netbuf_teardown(libxl__egc *egc,
         libxl__remus_teardown_done(egc, dss);
 }
 
+/* The buffer_op's value, not the value passed to kernel */
+enum {
+    tc_buffer_start,
+    tc_buffer_release
+};
+
+static int remus_netbuf_op(libxl__gc *gc, uint32_t domid,
+                           libxl__remus_state *remus_state,
+                           int buffer_op)
+{
+    int i, ret;
+
+    /* Convenience aliases */
+    libxl__remus_netbuf_state *const netbuf_state = remus_state->netbuf_state;
+
+    for (i = 0; i < netbuf_state->num_netbufs; ++i) {
+        if (buffer_op == tc_buffer_start)
+            ret = rtnl_qdisc_plug_buffer(netbuf_state->netbuf_qdisc_list[i]);
+        else
+            ret = 
rtnl_qdisc_plug_release_one(netbuf_state->netbuf_qdisc_list[i]);
+
+        if (!ret) {
+            ret = rtnl_qdisc_add(netbuf_state->nlsock,
+                                 netbuf_state->netbuf_qdisc_list[i],
+                                 NLM_F_REQUEST);
+            if (ret)
+                goto out;
+        }
+    }
+
+    return 0;
+
+out:
+    LOG(ERROR, "Remus: cannot do netbuf op %s on %s:%s",
+        ((buffer_op == tc_buffer_start) ?
+        "start_new_epoch" : "release_prev_epoch"),
+        netbuf_state->ifb_list[i], nl_geterror(ret));
+    return ERROR_FAIL;
+}
+
+int libxl__remus_netbuf_start_new_epoch(libxl__gc *gc, uint32_t domid,
+                                        libxl__remus_state *remus_state)
+{
+    return remus_netbuf_op(gc, domid, remus_state, tc_buffer_start);
+}
+
+int libxl__remus_netbuf_release_prev_epoch(libxl__gc *gc, uint32_t domid,
+                                           libxl__remus_state *remus_state)
+{
+    return remus_netbuf_op(gc, domid, remus_state, tc_buffer_release);
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/tools/libxl/libxl_nonetbuffer.c b/tools/libxl/libxl_nonetbuffer.c
index 559d0a6..92f35bc 100644
--- a/tools/libxl/libxl_nonetbuffer.c
+++ b/tools/libxl/libxl_nonetbuffer.c
@@ -33,6 +33,20 @@ void libxl__remus_netbuf_teardown(libxl__egc *egc,
 {
 }
 
+int libxl__remus_netbuf_start_new_epoch(libxl__gc *gc, uint32_t domid,
+                                        libxl__remus_state *remus_state)
+{
+    LOG(ERROR, "Remus: No support for network buffering");
+    return ERROR_FAIL;
+}
+
+int libxl__remus_netbuf_release_prev_epoch(libxl__gc *gc, uint32_t domid,
+                                           libxl__remus_state *remus_state)
+{
+    LOG(ERROR, "Remus: No support for network buffering");
+    return ERROR_FAIL;
+}
+
 /*
  * Local variables:
  * mode: C
-- 
1.8.3.2


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