Add VNET_BUFFER_F_AVAIL definitions

Add a check to make sure that the vlib and vnet buffer flag bit
definitions do not overlap.

The VNET_BUFFER_F_AVAIL1...8 definitions allow out-of-tree codes to:

  #define VNET_BUFFER_F_MY_USECASE VNET_BUFFER_F_AVAIL1

and so on. This avoids introducing irrelevant and/or proprietary bit
definitions into vnet/buffer.h, and hopefully minimizes merge pain for
everyone involved.

Change-Id: I5be4f61dceb81b5bfca005f6d609ade074af205b
Signed-off-by: Dave Barach <dave@barachs.net>

src/vlib/buffer.h

@@ -98,6 +98,7 @@ enum
   /* User defined buffer flags. */
 #define LOG2_VLIB_BUFFER_FLAG_USER(n) (32 - (n))
 #define VLIB_BUFFER_FLAG_USER(n) (1 << LOG2_VLIB_BUFFER_FLAG_USER(n))
+#define VLIB_BUFFER_FLAGS_ALL (0x1f)
 
 /* VLIB buffer representation. */
 typedef struct

src/vnet/buffer.h

@@ -44,6 +44,7 @@
 
 /**
  * Flags that are set in the high order bits of ((vlib_buffer*)b)->flags
+ *
  */
 #define foreach_vnet_buffer_flag                        \
   _( 1, L4_CHECKSUM_COMPUTED, "l4-cksum-computed", 1)	\
@@ -64,7 +65,26 @@
   _(16, L4_HDR_OFFSET_VALID, "l4_hdr_offset_valid", 0)  \
   _(17, FLOW_REPORT, "flow-report", 1)                  \
   _(18, IS_DVR, "dvr", 1)                               \
-  _(19, QOS_DATA_VALID, "qos-data-valid", 0)
+  _(19, QOS_DATA_VALID, "qos-data-valid", 0)            \
+  _(20, AVAIL1, "avail1", 1)                            \
+  _(21, AVAIL2, "avail2", 1)                            \
+  _(22, AVAIL3, "avail3", 1)                            \
+  _(23, AVAIL4, "avail4", 1)                            \
+  _(24, AVAIL5, "avail5", 1)                            \
+  _(25, AVAIL6, "avail6", 1)                            \
+  _(26, AVAIL7, "avail7", 1)                            \
+  _(27, AVAIL8, "avail8", 1)
+
+/*
+ * Please allocate the FIRST available bit, redefine
+ * AVAIL 1 ... AVAILn-1, and remove AVAILn. Please maintain the
+ * VNET_BUFFER_FLAGS_ALL_AVAIL definition.
+ */
+
+#define VNET_BUFFER_FLAGS_ALL_AVAIL                                     \
+  (VNET_BUFFER_F_AVAIL1 | VNET_BUFFER_F_AVAIL2 | VNET_BUFFER_F_AVAIL3 | \
+   VNET_BUFFER_F_AVAIL4 | VNET_BUFFER_F_AVAIL5 | VNET_BUFFER_F_AVAIL6 | \
+   VNET_BUFFER_F_AVAIL7)
 
 #define VNET_BUFFER_FLAGS_VLAN_BITS \
   (VNET_BUFFER_F_VLAN_1_DEEP | VNET_BUFFER_F_VLAN_2_DEEP)
@@ -83,6 +103,10 @@ enum
 #undef _
 };
 
+/* Make sure that the vnet and vlib bits are disjoint */
+STATIC_ASSERT (((VNET_BUFFER_FLAGS_ALL_AVAIL & VLIB_BUFFER_FLAGS_ALL) == 0),
+	       "VLIB / VNET buffer flags overlap");
+
 #define foreach_buffer_opaque_union_subtype     \
 _(ip)                                           \
 _(l2)                                           \