diff mbox series

[net-next,09/10] igc: Avoid unnecessary link down event in XDP_SETUP_PROG process

Message ID 20250210192352.3799673-10-anthony.l.nguyen@intel.com (mailing list archive)
State Accepted
Commit be324b790368c1522f07c6bb5654122e07b5e588
Delegated to: Netdev Maintainers
Headers show
Series Intel Wired LAN Driver Updates 2025-02-10 (ice, igc, e1000e) | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 10 of 10 maintainers
netdev/build_clang success Errors and warnings before: 2 this patch: 2
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 37 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2025-02-11--15-00 (tests: 889)

Commit Message

Tony Nguyen Feb. 10, 2025, 7:23 p.m. UTC 
From: Song Yoong Siang <yoong.siang.song@intel.com>

The igc_close()/igc_open() functions are too drastic for installing a new
XDP prog because they cause undesirable link down event and device reset.

To avoid delays in Ethernet traffic, improve the XDP_SETUP_PROG process by
using the same sequence as igc_xdp_setup_pool(), which performs only the
necessary steps, as follows:
 1. stop the traffic and clean buffer
 2. stop NAPI
 3. install the XDP program
 4. resume NAPI
 5. allocate buffer and resume the traffic

This patch has been tested using the 'ip link set xdpdrv' command to attach
a simple XDP prog that always returns XDP_PASS.

Before this patch, attaching xdp program will cause ptp4l to lose sync for
few seconds, as shown in ptp4l log below:
  ptp4l[198.082]: rms    4 max    8 freq   +906 +/-   2 delay    12 +/-   0
  ptp4l[199.082]: rms    3 max    4 freq   +906 +/-   3 delay    12 +/-   0
  ptp4l[199.536]: port 1 (enp2s0): link down
  ptp4l[199.536]: port 1 (enp2s0): SLAVE to FAULTY on FAULT_DETECTED (FT_UNSPECIFIED)
  ptp4l[199.600]: selected local clock 22abbc.fffe.bb1234 as best master
  ptp4l[199.600]: port 1 (enp2s0): assuming the grand master role
  ptp4l[199.600]: port 1 (enp2s0): master state recommended in slave only mode
  ptp4l[199.600]: port 1 (enp2s0): defaultDS.priority1 probably misconfigured
  ptp4l[202.266]: port 1 (enp2s0): link up
  ptp4l[202.300]: port 1 (enp2s0): FAULTY to LISTENING on INIT_COMPLETE
  ptp4l[205.558]: port 1 (enp2s0): new foreign master 44abbc.fffe.bb2144-1
  ptp4l[207.558]: selected best master clock 44abbc.fffe.bb2144
  ptp4l[207.559]: port 1 (enp2s0): LISTENING to UNCALIBRATED on RS_SLAVE
  ptp4l[208.308]: port 1 (enp2s0): UNCALIBRATED to SLAVE on MASTER_CLOCK_SELECTED
  ptp4l[208.933]: rms  742 max 1303 freq   -195 +/- 682 delay    12 +/-   0
  ptp4l[209.933]: rms  178 max  274 freq   +387 +/- 243 delay    12 +/-   0

After this patch, attaching xdp program no longer cause ptp4l to lose sync,
as shown in ptp4l log below:
  ptp4l[201.183]: rms    1 max    3 freq   +959 +/-   1 delay     8 +/-   0
  ptp4l[202.183]: rms    1 max    3 freq   +961 +/-   2 delay     8 +/-   0
  ptp4l[203.183]: rms    2 max    3 freq   +958 +/-   2 delay     8 +/-   0
  ptp4l[204.183]: rms    3 max    5 freq   +961 +/-   3 delay     8 +/-   0
  ptp4l[205.183]: rms    2 max    4 freq   +964 +/-   3 delay     8 +/-   0

Besides, before this patch, attaching xdp program will causes flood ping to
lose 10 packets, as shown in ping statistics below:
  --- 169.254.1.2 ping statistics ---
  100000 packets transmitted, 99990 received, +6 errors, 0.01% packet loss, time 34001ms
  rtt min/avg/max/mdev = 0.028/0.301/3104.360/13.838 ms, pipe 10, ipg/ewma 0.340/0.243 ms

After this patch, attaching xdp program no longer cause flood ping to loss
any packets, as shown in ping statistics below:
  --- 169.254.1.2 ping statistics ---
  100000 packets transmitted, 100000 received, 0% packet loss, time 32326ms
  rtt min/avg/max/mdev = 0.027/0.231/19.589/0.155 ms, pipe 2, ipg/ewma 0.323/0.322 ms

On the other hand, this patch has been tested with tools/testing/selftests/
bpf/xdp_hw_metadata app to make sure AF_XDP zero-copy is working fine with
XDP Tx and Rx metadata. Below is the result of last packet after received
10000 UDP packets with interval 1 ms:
  poll: 1 (0) skip=0 fail=0 redir=10000
  xsk_ring_cons__peek: 1
  0x55881c7ef7a8: rx_desc[9999]->addr=8f110 addr=8f110 comp_addr=8f110 EoP
  rx_hash: 0xFB9BB6A3 with RSS type:0x1
  HW RX-time:   1733923136269470866 (sec:1733923136.2695) delta to User RX-time sec:0.0000 (43.280 usec)
  XDP RX-time:   1733923136269482482 (sec:1733923136.2695) delta to User RX-time sec:0.0000 (31.664 usec)
  No rx_vlan_tci or rx_vlan_proto, err=-95
  0x55881c7ef7a8: ping-pong with csum=ab19 (want 315b) csum_start=34 csum_offset=6
  0x55881c7ef7a8: complete tx idx=9999 addr=f010
  HW TX-complete-time:   1733923136269591637 (sec:1733923136.2696) delta to User TX-complete-time sec:0.0001 (108.571 usec)
  XDP RX-time:   1733923136269482482 (sec:1733923136.2695) delta to User TX-complete-time sec:0.0002 (217.726 usec)
  HW RX-time:   1733923136269470866 (sec:1733923136.2695) delta to HW TX-complete-time sec:0.0001 (120.771 usec)
  0x55881c7ef7a8: complete rx idx=10127 addr=8f110

Signed-off-by: Song Yoong Siang <yoong.siang.song@intel.com>
Tested-by: Avigail Dahan <avigailx.dahan@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
---
 drivers/net/ethernet/intel/igc/igc_xdp.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/drivers/net/ethernet/intel/igc/igc_xdp.c b/drivers/net/ethernet/intel/igc/igc_xdp.c
index 13bbd3346e01..c538e6b18aad 100644
--- a/drivers/net/ethernet/intel/igc/igc_xdp.c
+++ b/drivers/net/ethernet/intel/igc/igc_xdp.c
@@ -14,6 +14,7 @@  int igc_xdp_set_prog(struct igc_adapter *adapter, struct bpf_prog *prog,
 	bool if_running = netif_running(dev);
 	struct bpf_prog *old_prog;
 	bool need_update;
+	unsigned int i;
 
 	if (dev->mtu > ETH_DATA_LEN) {
 		/* For now, the driver doesn't support XDP functionality with
@@ -24,8 +25,13 @@  int igc_xdp_set_prog(struct igc_adapter *adapter, struct bpf_prog *prog,
 	}
 
 	need_update = !!adapter->xdp_prog != !!prog;
-	if (if_running && need_update)
-		igc_close(dev);
+	if (if_running && need_update) {
+		for (i = 0; i < adapter->num_rx_queues; i++) {
+			igc_disable_rx_ring(adapter->rx_ring[i]);
+			igc_disable_tx_ring(adapter->tx_ring[i]);
+			napi_disable(&adapter->rx_ring[i]->q_vector->napi);
+		}
+	}
 
 	old_prog = xchg(&adapter->xdp_prog, prog);
 	if (old_prog)
@@ -36,8 +42,13 @@  int igc_xdp_set_prog(struct igc_adapter *adapter, struct bpf_prog *prog,
 	else
 		xdp_features_clear_redirect_target(dev);
 
-	if (if_running && need_update)
-		igc_open(dev);
+	if (if_running && need_update) {
+		for (i = 0; i < adapter->num_rx_queues; i++) {
+			napi_enable(&adapter->rx_ring[i]->q_vector->napi);
+			igc_enable_tx_ring(adapter->tx_ring[i]);
+			igc_enable_rx_ring(adapter->rx_ring[i]);
+		}
+	}
 
 	return 0;
 }