[ovs-dev,v10,06/14] dp-packet: Handle multi-seg mbufs in helper funcs.

diff --git a/lib/dp-packet.c b/lib/dp-packet.c
index 782e7c2..2aaeaae 100644
--- a/lib/dp-packet.c
+++ b/lib/dp-packet.c
@@ -41,11 +41,11 @@  static void
 dp_packet_use__(struct dp_packet *b, void *base, size_t allocated,
              enum dp_packet_source source)
 {
+    dp_packet_init__(b, allocated, source);
+
     dp_packet_set_base(b, base);
     dp_packet_set_data(b, base);
     dp_packet_set_size(b, 0);
-
-    dp_packet_init__(b, allocated, source);
 }
 
 /* Initializes 'b' as an empty dp_packet that contains the 'allocated' bytes of
diff --git a/lib/dp-packet.h b/lib/dp-packet.h
index 4545041..259b470 100644
--- a/lib/dp-packet.h
+++ b/lib/dp-packet.h
@@ -185,9 +185,25 @@  dp_packet_delete(struct dp_packet *b)
 static inline void *
 dp_packet_at(const struct dp_packet *b, size_t offset, size_t size)
 {
-    return offset + size <= dp_packet_size(b)
-           ? (char *) dp_packet_data(b) + offset
-           : NULL;
+    if (offset + size > dp_packet_size(b)) {
+        return NULL;
+    }
+
+#ifdef DPDK_NETDEV
+    if (b->source == DPBUF_DPDK) {
+        struct rte_mbuf *buf = CONST_CAST(struct rte_mbuf *, &b->mbuf);
+
+        while (buf && offset > buf->data_len) {
+            offset -= buf->data_len;
+
+            buf = buf->next;
+        }
+
+        return buf ? rte_pktmbuf_mtod_offset(buf, char *, offset) : NULL;
+    }
+#endif
+
+    return (char *) dp_packet_data(b) + offset;
 }
 
 /* Returns a pointer to byte 'offset' in 'b', which must contain at least
@@ -196,13 +212,23 @@  static inline void *
 dp_packet_at_assert(const struct dp_packet *b, size_t offset, size_t size)
 {
     ovs_assert(offset + size <= dp_packet_size(b));
-    return ((char *) dp_packet_data(b)) + offset;
+    return dp_packet_at(b, offset, size);
 }
 
 /* Returns a pointer to byte following the last byte of data in use in 'b'. */
 static inline void *
 dp_packet_tail(const struct dp_packet *b)
 {
+#ifdef DPDK_NETDEV
+    if (b->source == DPBUF_DPDK) {
+        struct rte_mbuf *buf = CONST_CAST(struct rte_mbuf *, &b->mbuf);
+        /* Find last segment where data ends, meaning the tail of the chained
+         *  mbufs must be there */
+        buf = rte_pktmbuf_lastseg(buf);
+
+        return rte_pktmbuf_mtod_offset(buf, void *, buf->data_len);
+    }
+#endif
     return (char *) dp_packet_data(b) + dp_packet_size(b);
 }
 
@@ -211,6 +237,15 @@  dp_packet_tail(const struct dp_packet *b)
 static inline void *
 dp_packet_end(const struct dp_packet *b)
 {
+#ifdef DPDK_NETDEV
+    if (b->source == DPBUF_DPDK) {
+        struct rte_mbuf *buf = CONST_CAST(struct rte_mbuf *, &(b->mbuf));
+
+        buf = rte_pktmbuf_lastseg(buf);
+
+        return (char *) buf->buf_addr + buf->buf_len;
+    }
+#endif
     return (char *) dp_packet_base(b) + dp_packet_get_allocated(b);
 }
 
@@ -236,6 +271,15 @@  dp_packet_tailroom(const struct dp_packet *b)
 static inline void
 dp_packet_clear(struct dp_packet *b)
 {
+#ifdef DPDK_NETDEV
+    if (b->source == DPBUF_DPDK) {
+        /* sets pkt_len and data_len to zero and frees unused mbufs */
+        dp_packet_set_size(b, 0);
+        rte_pktmbuf_reset(&b->mbuf);
+
+        return;
+    }
+#endif
     dp_packet_set_data(b, dp_packet_base(b));
     dp_packet_set_size(b, 0);
 }
@@ -248,28 +292,47 @@  dp_packet_pull(struct dp_packet *b, size_t size)
     void *data = dp_packet_data(b);
     ovs_assert(dp_packet_size(b) - dp_packet_l2_pad_size(b) >= size);
     dp_packet_set_data(b, (char *) dp_packet_data(b) + size);
-    dp_packet_set_size(b, dp_packet_size(b) - size);
+#ifdef DPDK_NETDEV
+    b->mbuf.pkt_len -= size;
+#else
+    b->size_ -= size;
+#endif
+
     return data;
 }
 
+#ifdef DPDK_NETDEV
+/* Similar to dp_packet_try_pull() but doesn't actually pull any data, only
+ * checks if it could and returns true or false accordingly.
+ *
+ * Valid for dp_packets carrying mbufs only. */
+static inline bool
+dp_packet_mbuf_may_pull(const struct dp_packet *b, size_t size) {
+    if (size > b->mbuf.data_len) {
+        return false;
+    }
+
+    return true;
+}
+#endif
+
 /* If 'b' has at least 'size' bytes of data, removes that many bytes from the
  * head end of 'b' and returns the first byte removed.  Otherwise, returns a
  * null pointer without modifying 'b'. */
 static inline void *
 dp_packet_try_pull(struct dp_packet *b, size_t size)
 {
+#ifdef DPDK_NETDEV
+    if (!dp_packet_mbuf_may_pull(b, size)) {
+        return NULL;
+    }
+#endif
+
     return dp_packet_size(b) - dp_packet_l2_pad_size(b) >= size
         ? dp_packet_pull(b, size) : NULL;
 }
 
 static inline bool
-dp_packet_equal(const struct dp_packet *a, const struct dp_packet *b)
-{
-    return dp_packet_size(a) == dp_packet_size(b) &&
-           !memcmp(dp_packet_data(a), dp_packet_data(b), dp_packet_size(a));
-}
-
-static inline bool
 dp_packet_is_eth(const struct dp_packet *b)
 {
     return b->packet_type == htonl(PT_ETH);
@@ -311,6 +374,12 @@  dp_packet_set_l2_pad_size(struct dp_packet *b, uint8_t pad_size)
 static inline void *
 dp_packet_l2_5(const struct dp_packet *b)
 {
+#ifdef DPDK_NETDEV
+    if (!dp_packet_mbuf_may_pull(b, b->l2_5_ofs)) {
+        return NULL;
+    }
+#endif
+
     return b->l2_5_ofs != UINT16_MAX
            ? (char *) dp_packet_data(b) + b->l2_5_ofs
            : NULL;
@@ -327,6 +396,12 @@  dp_packet_set_l2_5(struct dp_packet *b, void *l2_5)
 static inline void *
 dp_packet_l3(const struct dp_packet *b)
 {
+#ifdef DPDK_NETDEV
+    if (!dp_packet_mbuf_may_pull(b, b->l3_ofs)) {
+        return NULL;
+    }
+#endif
+
     return b->l3_ofs != UINT16_MAX
            ? (char *) dp_packet_data(b) + b->l3_ofs
            : NULL;
@@ -341,6 +416,12 @@  dp_packet_set_l3(struct dp_packet *b, void *l3)
 static inline void *
 dp_packet_l4(const struct dp_packet *b)
 {
+#ifdef DPDK_NETDEV
+    if (!dp_packet_mbuf_may_pull(b, b->l4_ofs)) {
+        return NULL;
+    }
+#endif
+
     return b->l4_ofs != UINT16_MAX
            ? (char *) dp_packet_data(b) + b->l4_ofs
            : NULL;
@@ -355,6 +436,27 @@  dp_packet_set_l4(struct dp_packet *b, void *l4)
 static inline size_t
 dp_packet_l4_size(const struct dp_packet *b)
 {
+#ifdef DPDK_NETDEV
+    if (b->source == DPBUF_DPDK) {
+        if (!dp_packet_mbuf_may_pull(b, b->l4_ofs)) {
+            return 0;
+        }
+
+        struct rte_mbuf *mbuf = CONST_CAST(struct rte_mbuf *, &b->mbuf);
+        size_t l4_size = mbuf->data_len - b->l4_ofs;
+
+        mbuf = mbuf->next;
+        while (mbuf) {
+            l4_size += mbuf->data_len;
+
+            mbuf = mbuf->next;
+        }
+
+        l4_size -= dp_packet_l2_pad_size(b);
+
+        return l4_size;
+    }
+#endif
     return b->l4_ofs != UINT16_MAX
         ? (const char *)dp_packet_tail(b) - (const char *)dp_packet_l4(b)
         - dp_packet_l2_pad_size(b)
@@ -408,6 +510,28 @@  dp_packet_get_nd_payload(const struct dp_packet *b)
 #ifdef DPDK_NETDEV
 BUILD_ASSERT_DECL(offsetof(struct dp_packet, mbuf) == 0);
 
+static inline bool
+dp_packet_equal(const struct dp_packet *a, const struct dp_packet *b)
+{
+    const struct rte_mbuf *m_a = &a->mbuf;
+    const struct rte_mbuf *m_b = &b->mbuf;
+    if (dp_packet_size(a) != dp_packet_size(b) ||
+        m_a->nb_segs != m_b->nb_segs) {
+        return false;
+    }
+
+    while (m_a != NULL && m_b != NULL) {
+        if (m_a->data_len != m_b->data_len ||
+            memcmp(dp_packet_data(a), dp_packet_data(b), m_a->data_len)) {
+            return false;
+        }
+
+        m_a = m_a->next;
+        m_b = m_b->next;
+    }
+    return true;
+}
+
 static inline void *
 dp_packet_base(const struct dp_packet *b)
 {
@@ -517,7 +641,7 @@  __packet_set_data(struct dp_packet *b, uint16_t v)
 static inline uint16_t
 dp_packet_get_allocated(const struct dp_packet *b)
 {
-    return b->mbuf.buf_len;
+    return b->mbuf.nb_segs * b->mbuf.buf_len;
 }
 
 static inline void
@@ -526,6 +650,13 @@  dp_packet_set_allocated(struct dp_packet *b, uint16_t s)
     b->mbuf.buf_len = s;
 }
 #else
+static inline bool
+dp_packet_equal(const struct dp_packet *a, const struct dp_packet *b)
+{
+    return dp_packet_size(a) == dp_packet_size(b) &&
+           !memcmp(dp_packet_data(a), dp_packet_data(b), dp_packet_size(a));
+}
+
 static inline void *
 dp_packet_base(const struct dp_packet *b)
 {
@@ -627,10 +758,9 @@  dp_packet_set_data(struct dp_packet *b, void *data)
 }
 
 static inline void
-dp_packet_reset_packet(struct dp_packet *b, int off)
+dp_packet_reset_packet(struct dp_packet *b, size_t off)
 {
-    dp_packet_set_size(b, dp_packet_size(b) - off);
-    dp_packet_set_data(b, ((unsigned char *) dp_packet_data(b) + off));
+    dp_packet_try_pull(b, off);
     dp_packet_reset_offsets(b);
 }