[dpdk-dev] [PATCH] net/af_xdp: fix build warning for kernels < 5.4

[Ciara Loftus <ciara.loftus@intel.com>]

Prior to this change, two implementations of rx_syscall_handler
existed although only one was needed (for the zero copy path which
is only available from kernel 5.4 and onwards). Remove the second
definition from compat.h and move the first definition back to where
it is called in the Rx function. Doing this removes a build warning
on kernels before 5.4 which complained about the second function
being defined but not used.

Fixes: 2aa51cdd559e ("net/af_xdp: fix trigger for syscall on Tx")

Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
---
 drivers/net/af_xdp/compat.h         | 25 -------------------------
 drivers/net/af_xdp/rte_eth_af_xdp.c | 14 ++++++++++++--
 2 files changed, 12 insertions(+), 27 deletions(-)

diff --git a/drivers/net/af_xdp/compat.h b/drivers/net/af_xdp/compat.h
index 52fd447b69..3880dc7dd7 100644
--- a/drivers/net/af_xdp/compat.h
+++ b/drivers/net/af_xdp/compat.h
@@ -42,37 +42,12 @@ create_shared_socket(struct xsk_socket **xsk_ptr __rte_unused,
 #endif
 
 #ifdef XDP_USE_NEED_WAKEUP
-static void
-rx_syscall_handler(struct xsk_ring_prod *q, uint32_t busy_budget,
-		   struct pollfd *fds, struct xsk_socket *xsk)
-{
-	/* we can assume a kernel >= 5.11 is in use if busy polling is enabled
-	 * and thus we can safely use the recvfrom() syscall which is only
-	 * supported for AF_XDP sockets in kernels >= 5.11.
-	 */
-	if (busy_budget) {
-		(void)recvfrom(xsk_socket__fd(xsk), NULL, 0,
-			MSG_DONTWAIT, NULL, NULL);
-		return;
-	}
-
-	if (xsk_ring_prod__needs_wakeup(q))
-		(void)poll(fds, 1, 1000);
-}
 static int
 tx_syscall_needed(struct xsk_ring_prod *q)
 {
 	return xsk_ring_prod__needs_wakeup(q);
 }
 #else
-static void
-rx_syscall_handler(struct xsk_ring_prod *q __rte_unused, uint32_t busy_budget,
-		   struct pollfd *fds __rte_unused, struct xsk_socket *xsk)
-{
-	if (busy_budget)
-		(void)recvfrom(xsk_socket__fd(xsk), NULL, 0,
-			MSG_DONTWAIT, NULL, NULL);
-}
 static int
 tx_syscall_needed(struct xsk_ring_prod *q __rte_unused)
 {
diff --git a/drivers/net/af_xdp/rte_eth_af_xdp.c b/drivers/net/af_xdp/rte_eth_af_xdp.c
index 0c91a40c4a..dd429969a3 100644
--- a/drivers/net/af_xdp/rte_eth_af_xdp.c
+++ b/drivers/net/af_xdp/rte_eth_af_xdp.c
@@ -272,8 +272,18 @@ af_xdp_rx_zc(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
 	nb_pkts = xsk_ring_cons__peek(rx, nb_pkts, &idx_rx);
 
 	if (nb_pkts == 0) {
-		rx_syscall_handler(&rxq->fq, rxq->busy_budget, &rxq->fds[0],
-				   rxq->xsk);
+		/* we can assume a kernel >= 5.11 is in use if busy polling is
+		 * enabled and thus we can safely use the recvfrom() syscall
+		 * which is only supported for AF_XDP sockets in kernels >=
+		 * 5.11.
+		 */
+		if (rxq->busy_budget) {
+			(void)recvfrom(xsk_socket__fd(rxq->xsk), NULL, 0,
+				       MSG_DONTWAIT, NULL, NULL);
+		} else if (xsk_ring_prod__needs_wakeup(fq)) {
+			(void)poll(&rxq->fds[0], 1, 1000);
+		}
+
 		return 0;
 	}
 
-- 
2.25.1