netdev - [PATCH bpf-next 05/10] ixgbe: xsk: terminate NAPI when XSK Rx queue gets full

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Date:   Tue,  5 Apr 2022 13:06:26 +0200
From:   Maciej Fijalkowski <maciej.fijalkowski@...el.com>
To:     bpf@...r.kernel.org, ast@...nel.org, daniel@...earbox.net,
        magnus.karlsson@...el.com, bjorn@...nel.org
Cc:     netdev@...r.kernel.org, brouer@...hat.com, maximmi@...dia.com,
        alexandr.lobakin@...el.com,
        Maciej Fijalkowski <maciej.fijalkowski@...el.com>
Subject: [PATCH bpf-next 05/10] ixgbe: xsk: terminate NAPI when XSK Rx queue gets full

Correlate -ENOBUFS that was returned from xdp_do_redirect() with a XSK
Rx queue being full. In such case, terminate the softirq processing and
let the user space to consume descriptors from XSK Rx queue so that
there is room that driver can use later on.

Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
---
 .../ethernet/intel/ixgbe/ixgbe_txrx_common.h  |  1 +
 drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c  | 23 ++++++++++++-------
 2 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h b/drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h
index bba3feaf3318..f1f69ce67420 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_txrx_common.h
@@ -8,6 +8,7 @@
 #define IXGBE_XDP_CONSUMED	BIT(0)
 #define IXGBE_XDP_TX		BIT(1)
 #define IXGBE_XDP_REDIR		BIT(2)
+#define IXGBE_XDP_EXIT		BIT(3)
 
 #define IXGBE_TXD_CMD (IXGBE_TXD_CMD_EOP | \
 		       IXGBE_TXD_CMD_RS)
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
index dd7ff66d422f..475244a2c6e4 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
@@ -109,9 +109,10 @@ static int ixgbe_run_xdp_zc(struct ixgbe_adapter *adapter,
 
 	if (likely(act == XDP_REDIRECT)) {
 		err = xdp_do_redirect(rx_ring->netdev, xdp, xdp_prog);
-		if (err)
-			goto out_failure;
-		return IXGBE_XDP_REDIR;
+		if (!err)
+			return IXGBE_XDP_REDIR;
+		result = (err == -ENOBUFS) ? IXGBE_XDP_EXIT : IXGBE_XDP_CONSUMED;
+		goto out_failure;
 	}
 
 	switch (act) {
@@ -130,6 +131,9 @@ static int ixgbe_run_xdp_zc(struct ixgbe_adapter *adapter,
 		if (result == IXGBE_XDP_CONSUMED)
 			goto out_failure;
 		break;
+	case XDP_DROP:
+		result = IXGBE_XDP_CONSUMED;
+		break;
 	default:
 		bpf_warn_invalid_xdp_action(rx_ring->netdev, xdp_prog, act);
 		fallthrough;
@@ -137,9 +141,6 @@ static int ixgbe_run_xdp_zc(struct ixgbe_adapter *adapter,
 out_failure:
 		trace_xdp_exception(rx_ring->netdev, xdp_prog, act);
 		fallthrough; /* handle aborts by dropping packet */
-	case XDP_DROP:
-		result = IXGBE_XDP_CONSUMED;
-		break;
 	}
 	return result;
 }
@@ -304,10 +305,16 @@ int ixgbe_clean_rx_irq_zc(struct ixgbe_q_vector *q_vector,
 		xdp_res = ixgbe_run_xdp_zc(adapter, rx_ring, bi->xdp);
 
 		if (xdp_res) {
-			if (xdp_res & (IXGBE_XDP_TX | IXGBE_XDP_REDIR))
+			if (xdp_res == IXGBE_XDP_EXIT) {
+				failure = true;
+				xsk_buff_free(bi->xdp);
+				ixgbe_inc_ntc(rx_ring);
+				break;
+			} else if (xdp_res & (IXGBE_XDP_TX | IXGBE_XDP_REDIR)) {
 				xdp_xmit |= xdp_res;
-			else
+			} else {
 				xsk_buff_free(bi->xdp);
+			}
 
 			bi->xdp = NULL;
 			total_rx_packets++;
-- 
2.33.1