[PATCH 09/12] vu_common: Accept explicit iovec counts in vu_set_element()

[Laurent Vivier <lvivier@redhat.com>]

Previously, vu_set_element() derived the number of iovec entries from
whether the pointer was NULL or not (using !!out_sg and !!in_sg). This
implicitly limited each virtqueue element to at most one iovec per
direction.

Change the function signature to accept explicit out_num and in_num
parameters, allowing callers to specify multiple iovec entries per
element when needed. Update all existing call sites to pass the
equivalent values (0 for NULL pointers, 1 for valid pointers).

No functional change.

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
---
 tcp_vu.c    |  4 ++--
 vu_common.c |  5 +++--
 vu_common.h | 13 ++++++++-----
 3 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/tcp_vu.c b/tcp_vu.c
index 92667507ac9b..77d6e75496a0 100644
--- a/tcp_vu.c
+++ b/tcp_vu.c
@@ -87,7 +87,7 @@ int tcp_vu_send_flag(const struct ctx *c, struct tcp_tap_conn *conn, int flags)
 
 	hdrlen = tcp_vu_hdrlen(CONN_V6(conn));
 
-	vu_set_element(&flags_elem[0], NULL, &flags_iov[0]);
+	vu_set_element(&flags_elem[0], 0, NULL, 1, &flags_iov[0]);
 
 	elem_cnt = vu_collect(vdev, vq, &flags_elem[0], 1,
 			      MAX(hdrlen + sizeof(*opts), ETH_ZLEN + VNET_HLEN), NULL);
@@ -149,7 +149,7 @@ int tcp_vu_send_flag(const struct ctx *c, struct tcp_tap_conn *conn, int flags)
 	nb_ack = 1;
 
 	if (flags & DUP_ACK) {
-		vu_set_element(&flags_elem[1], NULL, &flags_iov[1]);
+		vu_set_element(&flags_elem[1], 0, NULL, 1, &flags_iov[1]);
 
 		elem_cnt = vu_collect(vdev, vq, &flags_elem[1], 1,
 				      flags_elem[0].in_sg[0].iov_len, NULL);
diff --git a/vu_common.c b/vu_common.c
index a8d5fcdaea83..b6753a556049 100644
--- a/vu_common.c
+++ b/vu_common.c
@@ -59,12 +59,13 @@ int vu_packet_check_range(struct vdev_memory *memory,
  * @iov:	Array of iovec to assign to virtqueue element
  * @elem_cnt:	Number of virtqueue element
  */
-void vu_init_elem(struct vu_virtq_element *elem, struct iovec *iov, int elem_cnt)
+void vu_init_elem(struct vu_virtq_element *elem, struct iovec *iov,
+		  int elem_cnt)
 {
 	int i;
 
 	for (i = 0; i < elem_cnt; i++)
-		vu_set_element(&elem[i], NULL, &iov[i]);
+		vu_set_element(&elem[i], 0, NULL, 1, &iov[i]);
 }
 
 /**
diff --git a/vu_common.h b/vu_common.h
index 41cf18936300..c1d2ce888f12 100644
--- a/vu_common.h
+++ b/vu_common.h
@@ -32,15 +32,18 @@ static inline void *vu_payloadv6(void *base)
 /**
  * vu_set_element() - Initialize a vu_virtq_element
  * @elem:	Element to initialize
- * @out_sg:	One out iovec entry to set in elem
- * @in_sg:	One in iovec entry to set in elem
+ * @out_num:	Number of outgoing iovec buffers
+ * @out_sg:	Out iovec entry to set in elem
+ * @in_num:	Number of incoming iovec buffers
+ * @in_sg:	In iovec entry to set in elem
  */
 static inline void vu_set_element(struct vu_virtq_element *elem,
-				  struct iovec *out_sg, struct iovec *in_sg)
+				  unsigned int out_num, struct iovec *out_sg,
+				  unsigned int in_num, struct iovec *in_sg)
 {
-	elem->out_num = !!out_sg;
+	elem->out_num = out_num;
 	elem->out_sg = out_sg;
-	elem->in_num = !!in_sg;
+	elem->in_num = in_num;
 	elem->in_sg = in_sg;
 }
 
-- 
2.53.0