net: fix RARP generation

Due to a mistake operation from me, older version (v10) was merged to
master branch. It's the v11 should be applied. However, the master branch
is not rebase-able. Thus, this patch is made, from the diff between v10
and v11.

The diffs are:

- Add check for parameter and tailroom in rte_net_make_rarp_packet
- Allocate mbuf in rte_net_make_rarp_packet

Besides that, a link error is fixed when shared lib is enabled.

Fixes: 45ae05df824c ("net: add a helper for making RARP packet")
Fixes: c3ffdba0e88a ("vhost: use API to make RARP packet")

Signed-off-by: Xiao Wang <xiao.w.wang@intel.com>
Signed-off-by: Yuanhan Liu <yliu@fridaylinux.org>

lib/librte_net/Makefile

@@ -6,7 +6,7 @@ include $(RTE_SDK)/mk/rte.vars.mk
 LIB = librte_net.a
 
 CFLAGS += $(WERROR_FLAGS) -I$(SRCDIR) -O3
-LDLIBS += -lrte_mbuf -lrte_eal
+LDLIBS += -lrte_mbuf -lrte_eal -lrte_mempool
 
 EXPORT_MAP := rte_net_version.map
 LIBABIVER := 1

lib/librte_net/rte_arp.c

@@ -7,17 +7,28 @@
 #include <rte_arp.h>
 
 #define RARP_PKT_SIZE	64
-int
-rte_net_make_rarp_packet(struct rte_mbuf *mbuf, const struct ether_addr *mac)
+struct rte_mbuf *
+rte_net_make_rarp_packet(struct rte_mempool *mpool,
+		const struct ether_addr *mac)
 {
 	struct ether_hdr *eth_hdr;
 	struct arp_hdr *rarp;
+	struct rte_mbuf *mbuf;
 
-	if (mbuf->buf_len < RARP_PKT_SIZE)
-		return -1;
+	if (mpool == NULL)
+		return NULL;
+
+	mbuf = rte_pktmbuf_alloc(mpool);
+	if (mbuf == NULL)
+		return NULL;
+
+	eth_hdr = (struct ether_hdr *)rte_pktmbuf_append(mbuf, RARP_PKT_SIZE);
+	if (eth_hdr == NULL) {
+		rte_pktmbuf_free(mbuf);
+		return NULL;
+	}
 
 	/* Ethernet header. */
-	eth_hdr = rte_pktmbuf_mtod(mbuf, struct ether_hdr *);
 	memset(eth_hdr->d_addr.addr_bytes, 0xff, ETHER_ADDR_LEN);
 	ether_addr_copy(mac, &eth_hdr->s_addr);
 	eth_hdr->ether_type = htons(ETHER_TYPE_RARP);
@@ -35,8 +46,5 @@ rte_net_make_rarp_packet(struct rte_mbuf *mbuf, const struct ether_addr *mac)
 	memset(&rarp->arp_data.arp_sip, 0x00, 4);
 	memset(&rarp->arp_data.arp_tip, 0x00, 4);
 
-	mbuf->data_len = RARP_PKT_SIZE;
-	mbuf->pkt_len = RARP_PKT_SIZE;
-
-	return 0;
+	return mbuf;
 }

lib/librte_net/rte_arp.h

@@ -82,16 +82,17 @@ struct arp_hdr {
  *
  * Make a RARP packet based on MAC addr.
  *
- * @param mbuf
- *   Pointer to the rte_mbuf structure
+ * @param mpool
+ *   Pointer to the rte_mempool
  * @param mac
  *   Pointer to the MAC addr
  *
  * @return
- *   - 0 on success, negative on error
+ *   - RARP packet pointer on success, or NULL on error
  */
-int
-rte_net_make_rarp_packet(struct rte_mbuf *mbuf, const struct ether_addr *mac);
+struct rte_mbuf *
+rte_net_make_rarp_packet(struct rte_mempool *mpool,
+		const struct ether_addr *mac);
 
 #ifdef __cplusplus
 }

lib/librte_vhost/virtio_net.c

@@ -1162,19 +1162,13 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
 			rte_atomic16_cmpset((volatile uint16_t *)
 				&dev->broadcast_rarp.cnt, 1, 0))) {
 
-		rarp_mbuf = rte_pktmbuf_alloc(mbuf_pool);
+		rarp_mbuf = rte_net_make_rarp_packet(mbuf_pool, &dev->mac);
 		if (rarp_mbuf == NULL) {
 			RTE_LOG(ERR, VHOST_DATA,
-				"Failed to allocate memory for mbuf.\n");
+				"Failed to make RARP packet.\n");
 			return 0;
 		}
-
-		if (rte_net_make_rarp_packet(rarp_mbuf, &dev->mac) < 0) {
-			rte_pktmbuf_free(rarp_mbuf);
-			rarp_mbuf = NULL;
-		} else {
-			count -= 1;
-		}
+		count -= 1;
 	}
 
 	free_entries = *((volatile uint16_t *)&vq->avail->idx) -