[PATCH net] net: stmmac: fix call trace when stmmac_xdp_xmit() is invoked

From: wei . fang
Date: Wed May 24 2023 - 09:03:04 EST

From: Wei Fang <wei.fang@xxxxxxx>

We encountered a kernel call trace issue which was related to
ndo_xdp_xmit callback on our i.MX8MP platform. The reproduce
steps show as follows.
1. The FEC port (eth0) connects to a PC port, and the PC uses
pktgen_sample03_burst_single_flow.sh to generate packets and
send these packets to the FEC port. Notice that the script must
be executed before step 2.
2. Run the "./xdp_redirect eth0 eth1" command on i.MX8MP, the
eth1 interface is the dwmac. Then there will be a call trace
issue soon. Please see the log for more details.
The root cause is that the NETDEV_XDP_ACT_NDO_XMIT feature is
enabled by default, so when the step 2 command is exexcuted
and packets have already been sent to eth0, the stmmac_xdp_xmit()
starts running before the stmmac_xdp_set_prog() finishes. To
resolve this issue, we disable the NETDEV_XDP_ACT_NDO_XMIT
feature by default and turn on/off this feature when the bpf
program is installed/uninstalled which just like the other
ethernet drivers.

Call Trace log:
[ 306.311271] ------------[ cut here ]------------
[ 306.315910] WARNING: CPU: 0 PID: 15 at lib/timerqueue.c:55 timerqueue_del+0x68/0x70
[ 306.323590] Modules linked in:
[ 306.326654] CPU: 0 PID: 15 Comm: ksoftirqd/0 Not tainted 6.4.0-rc1+ #37
[ 306.333277] Hardware name: NXP i.MX8MPlus EVK board (DT)
[ 306.338591] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 306.345561] pc : timerqueue_del+0x68/0x70
[ 306.349577] lr : __remove_hrtimer+0x5c/0xa0
[ 306.353777] sp : ffff80000b7c3920
[ 306.357094] x29: ffff80000b7c3920 x28: 0000000000000000 x27: 0000000000000001
[ 306.364244] x26: ffff80000a763a40 x25: ffff0000d0285a00 x24: 0000000000000001
[ 306.371390] x23: 0000000000000001 x22: ffff000179389a40 x21: 0000000000000000
[ 306.378537] x20: ffff000179389aa0 x19: ffff0000d2951308 x18: 0000000000001000
[ 306.385686] x17: f1d3000000000000 x16: 00000000c39c1000 x15: 55e99bbe00001a00
[ 306.392835] x14: 09000900120aa8c0 x13: e49af1d300000000 x12: 000000000000c39c
[ 306.399987] x11: 100055e99bbe0000 x10: ffff8000090b1048 x9 : ffff8000081603fc
[ 306.407133] x8 : 000000000000003c x7 : 000000000000003c x6 : 0000000000000001
[ 306.414284] x5 : ffff0000d2950980 x4 : 0000000000000000 x3 : 0000000000000000
[ 306.421432] x2 : 0000000000000001 x1 : ffff0000d2951308 x0 : ffff0000d2951308
[ 306.428585] Call trace:
[ 306.431035] timerqueue_del+0x68/0x70
[ 306.434706] __remove_hrtimer+0x5c/0xa0
[ 306.438549] hrtimer_start_range_ns+0x2bc/0x370
[ 306.443089] stmmac_xdp_xmit+0x174/0x1b0
[ 306.447021] bq_xmit_all+0x194/0x4b0
[ 306.450612] __dev_flush+0x4c/0x98
[ 306.454024] xdp_do_flush+0x18/0x38
[ 306.457522] fec_enet_rx_napi+0x6c8/0xc68
[ 306.461539] __napi_poll+0x40/0x220
[ 306.465038] net_rx_action+0xf8/0x240
[ 306.468707] __do_softirq+0x128/0x3a8
[ 306.472378] run_ksoftirqd+0x40/0x58
[ 306.475961] smpboot_thread_fn+0x1c4/0x288
[ 306.480068] kthread+0x124/0x138
[ 306.483305] ret_from_fork+0x10/0x20
[ 306.486889] ---[ end trace 0000000000000000 ]---

Fixes: 66c0e13ad236 ("drivers: net: turn on XDP features")
Signed-off-by: Wei Fang <wei.fang@xxxxxxx>
---
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 3 +--
drivers/net/ethernet/stmicro/stmmac/stmmac_xdp.c | 6 ++++++
2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 0fca81507a77..52cab9de05f2 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -7233,8 +7233,7 @@ int stmmac_dvr_probe(struct device *device,
ndev->hw_features = NETIF_F_SG | NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM |
NETIF_F_RXCSUM;
ndev->xdp_features = NETDEV_XDP_ACT_BASIC | NETDEV_XDP_ACT_REDIRECT |
- NETDEV_XDP_ACT_XSK_ZEROCOPY |
- NETDEV_XDP_ACT_NDO_XMIT;
+ NETDEV_XDP_ACT_XSK_ZEROCOPY;

ret = stmmac_tc_init(priv, priv);
if (!ret) {
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_xdp.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_xdp.c
index 9d4d8c3dad0a..aa6f16d3df64 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_xdp.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_xdp.c
@@ -117,6 +117,9 @@ int stmmac_xdp_set_prog(struct stmmac_priv *priv, struct bpf_prog *prog,
return -EOPNOTSUPP;
}

+ if (!prog)
+ xdp_features_clear_redirect_target(dev);
+
need_update = !!priv->xdp_prog != !!prog;
if (if_running && need_update)
stmmac_xdp_release(dev);
@@ -131,5 +134,8 @@ int stmmac_xdp_set_prog(struct stmmac_priv *priv, struct bpf_prog *prog,
if (if_running && need_update)
stmmac_xdp_open(dev);

+ if (prog)
+ xdp_features_set_redirect_target(dev, false);
+
return 0;
}
--
2.25.1