If XDP traffic runs on a CPU which is greater than or equal to
the number of the Tx queues of the NIC, then vmxnet3_xdp_get_tq()
always picks up queue 0 for transmission as it uses reciprocal scale
instead of simple modulo operation.
vmxnet3_xdp_xmit() and vmxnet3_xdp_xmit_frame() use the above
returned queue without any locking which can lead to race conditions
when multiple XDP xmits run in parallel on different CPU's.
This patch uses a simple module scheme when the current CPU equals or
exceeds the number of Tx queues on the NIC. It also adds locking in
vmxnet3_xdp_xmit() and vmxnet3_xdp_xmit_frame() functions.
Fixes: 54f00cce1178 ("vmxnet3: Add XDP support.")
Signed-off-by: Sankararaman Jayaraman <sankararaman.jayaraman@xxxxxxxxxxxx>
Signed-off-by: Ronak Doshi <ronak.doshi@xxxxxxxxxxxx>
---
drivers/net/vmxnet3/vmxnet3_xdp.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
diff --git a/drivers/net/vmxnet3/vmxnet3_xdp.c b/drivers/net/vmxnet3/vmxnet3_xdp.c
index 1341374a4588..5f177e77cfcb 100644
--- a/drivers/net/vmxnet3/vmxnet3_xdp.c
+++ b/drivers/net/vmxnet3/vmxnet3_xdp.c
@@ -1,7 +1,7 @@
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Linux driver for VMware's vmxnet3 ethernet NIC.
- * Copyright (C) 2008-2023, VMware, Inc. All Rights Reserved.
+ * Copyright (C) 2008-2025, VMware, Inc. All Rights Reserved.
* Maintained by: pv-drivers@xxxxxxxxxx
*
*/
@@ -28,7 +28,7 @@ vmxnet3_xdp_get_tq(struct vmxnet3_adapter *adapter)
if (likely(cpu < tq_number))
tq = &adapter->tx_queue[cpu];
else
- tq = &adapter->tx_queue[reciprocal_scale(cpu, tq_number)];
+ tq = &adapter->tx_queue[cpu % tq_number];
return tq;
}
@@ -123,7 +123,9 @@ vmxnet3_xdp_xmit_frame(struct vmxnet3_adapter *adapter,
struct page *page;
u32 buf_size;
u32 dw2;
+ unsigned long irq_flags;
+ spin_lock_irqsave(&tq->tx_lock, irq_flags);
dw2 = (tq->tx_ring.gen ^ 0x1) << VMXNET3_TXD_GEN_SHIFT;
dw2 |= xdpf->len;
ctx.sop_txd = tq->tx_ring.base + tq->tx_ring.next2fill;
@@ -134,6 +136,7 @@ vmxnet3_xdp_xmit_frame(struct vmxnet3_adapter *adapter,
if (vmxnet3_cmd_ring_desc_avail(&tq->tx_ring) == 0) {
tq->stats.tx_ring_full++;
+ spin_unlock_irqrestore(&tq->tx_lock, irq_flags);
return -ENOSPC;
}
@@ -142,8 +145,10 @@ vmxnet3_xdp_xmit_frame(struct vmxnet3_adapter *adapter,
tbi->dma_addr = dma_map_single(&adapter->pdev->dev,
xdpf->data, buf_size,
DMA_TO_DEVICE);
- if (dma_mapping_error(&adapter->pdev->dev, tbi->dma_addr))
+ if (dma_mapping_error(&adapter->pdev->dev, tbi->dma_addr)) {
+ spin_unlock_irqrestore(&tq->tx_lock, irq_flags);
return -EFAULT;
+ }
tbi->map_type |= VMXNET3_MAP_SINGLE;
} else { /* XDP buffer from page pool */
page = virt_to_page(xdpf->data);
@@ -182,6 +187,7 @@ vmxnet3_xdp_xmit_frame(struct vmxnet3_adapter *adapter,
dma_wmb();
gdesc->dword[2] = cpu_to_le32(le32_to_cpu(gdesc->dword[2]) ^
VMXNET3_TXD_GEN);
+ spin_unlock_irqrestore(&tq->tx_lock, irq_flags);
/* No need to handle the case when tx_num_deferred doesn't reach
* threshold. Backend driver at hypervisor side will poll and reset
@@ -226,6 +232,7 @@ vmxnet3_xdp_xmit(struct net_device *dev,
struct vmxnet3_adapter *adapter = netdev_priv(dev);
struct vmxnet3_tx_queue *tq;
int i;
+ struct netdev_queue *nq;
if (unlikely(test_bit(VMXNET3_STATE_BIT_QUIESCED, &adapter->state)))
return -ENETDOWN;
@@ -236,6 +243,9 @@ vmxnet3_xdp_xmit(struct net_device *dev,
if (tq->stopped)
return -ENETDOWN;
+ nq = netdev_get_tx_queue(adapter->netdev, tq->qid);
+
+ __netif_tx_lock(nq, smp_processor_id());
for (i = 0; i < n; i++) {
if (vmxnet3_xdp_xmit_frame(adapter, frames[i], tq, true)) {
tq->stats.xdp_xmit_err++;
@@ -243,6 +253,7 @@ vmxnet3_xdp_xmit(struct net_device *dev,
}
}
tq->stats.xdp_xmit += i;
+ __netif_tx_unlock(nq);
return i;
}
--
2.25.1
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