Re: [Qemu-devel] [PATCH V3 05/10] net/net.c: Add vnet header length to SocketReadState

[Jason Wang]

On 2017年04月28日 17:47, Zhang Chen wrote:
Address Jason Wang's comments add vnet header length to SocketReadState.

Instead of saying this, you can add "Suggested-by: Jason Wang 
<jasow...@redhat.com>" above your sign-off.

So we change net_fill_rstate() to read
struct  {int size; int vnet_hdr_len; const uint8_t buf[];}.

This makes me thinking about the backward compatibility. I think we'd 
better try to keep it as much as possible. E.g how about pack 
vnet_hdr_len into higher bits of size?

Thanks


Signed-off-by: Zhang Chen <zhangchen.f...@cn.fujitsu.com>
---
  include/net/net.h |  4 +++-
  net/net.c         | 24 ++++++++++++++++++++++--
  2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/include/net/net.h b/include/net/net.h
index 402d913..865cb98 100644
--- a/include/net/net.h
+++ b/include/net/net.h
@@ -115,9 +115,11 @@ typedef struct NICState {
  } NICState;
  
  struct SocketReadState {
-    int state; /* 0 = getting length, 1 = getting data */
+    /* 0 = getting length, 1 = getting vnet header length, 2 = getting data */
+    int state;
      uint32_t index;
      uint32_t packet_len;
+    uint32_t vnet_hdr_len;
      uint8_t buf[NET_BUFSIZE];
      SocketReadStateFinalize *finalize;
  };
diff --git a/net/net.c b/net/net.c
index f69260f..5a6b5ac 100644
--- a/net/net.c
+++ b/net/net.c
@@ -1639,8 +1639,12 @@ int net_fill_rstate(SocketReadState *rs, const uint8_t 
*buf, int size)
      unsigned int l;
  
      while (size > 0) {
-        /* reassemble a packet from the network */
-        switch (rs->state) { /* 0 = getting length, 1 = getting data */
+        /* Reassemble a packet from the network.
+         * 0 = getting length.
+         * 1 = getting vnet header length.
+         * 2 = getting data.
+         */
+        switch (rs->state) {
          case 0:
              l = 4 - rs->index;
              if (l > size) {
@@ -1658,6 +1662,22 @@ int net_fill_rstate(SocketReadState *rs, const uint8_t 
*buf, int size)
              }
              break;
          case 1:
+            l = 4 - rs->index;
+            if (l > size) {
+                l = size;
+            }
+            memcpy(rs->buf + rs->index, buf, l);
+            buf += l;
+            size -= l;
+            rs->index += l;
+            if (rs->index == 4) {
+                /* got vnet header length */
+                rs->vnet_hdr_len = ntohl(*(uint32_t *)rs->buf);
+                rs->index = 0;
+                rs->state = 2;
+            }
+            break;
+        case 2:
              l = rs->packet_len - rs->index;
              if (l > size) {
                  l = size;