[PATCH] igc: Fix trigger of incorrect irq in igc_xsk_wakeup function

From: Behera, VIVEK

Date: Fri Dec 05 2025 - 07:40:03 EST

From 4e3ebdc0af6baa83ccfc17c61c1eb61408095ffd Mon Sep 17 00:00:00 2001

From: Vivek Behera <vivek.behera@xxxxxxxxxxx>

Date: Fri, 5 Dec 2025 10:26:05 +0100

Subject: [PATCH] igc: Fix trigger of incorrect irq in igc_xsk_wakeup function

When the i226 is configured to use only 2 combined queues using ethtool

or in an environment with only 2 active CPU cores the 4 irq lines

are used in a split configuration with one irq

assigned to each of the two rx and tx queues

(see console output below)

sudo ethtool -l enp1s0

Channel parameters for enp1s0:

Pre-set maximums:

RX: n/a

TX: n/a

Other: 1

Combined: 4

Current hardware settings:

RX: n/a

TX: n/a

Other: 1

Combined: 2

eddx@mvs:~$ cat /proc/interrupts | grep enp1s0

147: 1 0 IR-PCI-MSIX-0000:01:00.0 0-edge enp1s0

148: 8 0 IR-PCI-MSIX-0000:01:00.0 1-edge enp1s0-rx-0

149: 0 0 IR-PCI-MSIX-0000:01:00.0 2-edge enp1s0-rx-1

150: 26 0 IR-PCI-MSIX-0000:01:00.0 3-edge enp1s0-tx-0

151: 0 0 IR-PCI-MSIX-0000:01:00.0 4-edge enp1s0-tx-1

While testing with the RTC Testbench it was noticed

using the bpftrace that the

igc_xsk_wakeup when triggered by xsk_sendmsg

was triggering the incorrect irq for

tx-0(see trace below)

TIMESTAMP: 456992309829 | FUNCTION: igc_xsk_wakeup | ENTRY: RtcTxThread (PID: 945) - queue_id: 0

TIMESTAMP: 456992317157 | FUNCTION: igc_poll | ENTRY: irq/148-enp1s0- (PID: 948)

TIMESTAMP: 456993309408 | FUNCTION: igc_xsk_wakeup | ENTRY: RtcTxThread (PID: 945) - queue_id: 0

TIMESTAMP: 456993316591 | FUNCTION: igc_poll | ENTRY: irq/148-enp1s0- (PID: 948)

TIMESTAMP: 456994309630 | FUNCTION: igc_xsk_wakeup | ENTRY: RtcTxThread (PID: 945) - queue_id: 0

TIMESTAMP: 456994316674 | FUNCTION: igc_poll | ENTRY: irq/148-enp1s0- (PID: 948)

TIMESTAMP: 456995309493 | FUNCTION: igc_xsk_wakeup | ENTRY: RtcTxThread (PID: 945) - queue_id: 0

TIMESTAMP: 456995316593 | FUNCTION: igc_poll | ENTRY: irq/148-enp1s0- (PID: 948)

Due to this bug no XDP Zc send is possible in this split irq configuration.

This patch implements the correct logic of extracting the q_vectors saved

duirng the rx and tx ring allocation.

Furthermore the patch includes usage of flags provided by the ndo_xsk_wakeup

api to trigger the required irq. With this patch correct irqs are triggered

cat /proc/interrupts | grep enp1s0

161: 1 0 0 0 IR-PCI-MSIX-0000:01:00.0 0-edge enp1s0

162: 2 0 0 0 IR-PCI-MSIX-0000:01:00.0 1-edge enp1s0-rx-0

163: 359 0 0 0 IR-PCI-MSIX-0000:01:00.0 2-edge enp1s0-rx-1

164: 872005 0 0 0 IR-PCI-MSIX-0000:01:00.0 3-edge enp1s0-tx-0

165: 71 0 0 0 IR-PCI-MSIX-0000:01:00.0 4-edge enp1s0-tx-1

TIMESTAMP: 149658589239205 | FUNCTION: igc_xsk_wakeup | ENTRY: RtcTxThread (PID: 10633) - queue_id: 0

TIMESTAMP: 149658589244662 | FUNCTION: igc_poll | ENTRY: irq/164-enp1s0- (PID: 10593)

TIMESTAMP: 149658589293396 | FUNCTION: igc_poll | ENTRY: irq/164-enp1s0- (PID: 10593)

TIMESTAMP: 149658589295357 | FUNCTION: xsk_tx_completed | ENTRY: irq/164-enp1s0- (PID: 10593) - num_entries: 61

TIMESTAMP: 149658589342151 | FUNCTION: igc_poll | ENTRY: irq/164-enp1s0- (PID: 10593)

TIMESTAMP: 149658589343881 | FUNCTION: xsk_tx_completed | ENTRY: irq/164-enp1s0- (PID: 10593) - num_entries: 3

TIMESTAMP: 149658589391394 | FUNCTION: igc_poll | ENTRY: irq/164-enp1s0- (PID: 10593)

TIMESTAMP: 149658590239215 | FUNCTION: igc_xsk_wakeup | ENTRY: RtcTxThread (PID: 10633) - queue_id: 0

Signed-off-by: Vivek Behera <vivek.behera@xxxxxxxxxxx>

---

drivers/net/ethernet/intel/igc/igc_main.c | 31 +++++++++++++++++++----

1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c

index 7aafa60ba0c8..0cfcd20a2536 100644

--- a/drivers/net/ethernet/intel/igc/igc_main.c

+++ b/drivers/net/ethernet/intel/igc/igc_main.c

@@ -6930,21 +6930,42 @@ int igc_xsk_wakeup(struct net_device *dev, u32 queue_id, u32 flags)

if (!igc_xdp_is_enabled(adapter))

return -ENXIO;

- if (queue_id >= adapter->num_rx_queues)

+ if ((flags & XDP_WAKEUP_RX) && (flags & XDP_WAKEUP_TX)) {

+ /* If both TX and RX need to be woken up queue pair per IRQ is needed */

+ if (!(adapter->flags & IGC_FLAG_QUEUE_PAIRS))

+ return -EINVAL; /* igc queue pairs are not activated.

+ * Can't trigger irq

+ */

+ /* Just get the ring params from Rx */

+ if (queue_id >= adapter->num_rx_queues)

+ return -EINVAL;

+ ring = adapter->rx_ring[queue_id];

+ } else if (flags & XDP_WAKEUP_TX) {

+ if (queue_id >= adapter->num_tx_queues)

+ return -EINVAL;

+ /* Get the ring params from Tx */

+ ring = adapter->tx_ring[queue_id];

+ } else if (flags & XDP_WAKEUP_RX) {

+ if (queue_id >= adapter->num_rx_queues)

+ return -EINVAL;

+ /* Get the ring params from Rx */

+ ring = adapter->rx_ring[queue_id];

+ } else {

+ /* Invalid Flags */

return -EINVAL;

- ring = adapter->rx_ring[queue_id];

+ }

if (!ring->xsk_pool)

return -ENXIO;

- q_vector = adapter->q_vector[queue_id];

+ /* Retrieve the q_vector saved in the ring */

+ q_vector = ring->q_vector;

if (!napi_if_scheduled_mark_missed(&q_vector->napi))

igc_trigger_rxtxq_interrupt(adapter, q_vector);

return 0;

}

static ktime_t igc_get_tstamp(struct net_device *dev,

const struct skb_shared_hwtstamps *hwtstamps,

bool cycles)

2.34.1

Attachment: 0001-igc-Fix-trigger-of-incorrect-irq-in-igc_xsk_wakeup-f.patch
Description: 0001-igc-Fix-trigger-of-incorrect-irq-in-igc_xsk_wakeup-f.patch