From: Chaohai Chen <wdhh6@aliyun.com>
To: mst@redhat.com, jasowang@redhat.com, xuanzhuo@linux.alibaba.com,
eperezma@redhat.com
Cc: virtualization@lists.linux.dev, linux-kernel@vger.kernel.org,
Chaohai Chen <wdhh6@aliyun.com>
Subject: [PATCH v3] virtio_ring: Fix KCSAN warnings in virtqueue_enable_cb_delayed_split()
Date: Thu, 12 Mar 2026 01:05:10 +0800 [thread overview]
Message-ID: <20260311170510.288840-1-wdhh6@aliyun.com> (raw)
KCSAN warns as follow:
[ 109.277250] ==================================================================
[ 109.283600] BUG: KCSAN: data-race in virtqueue_enable_cb_delayed_split+0x10f/0x170
[ 109.295263] race at unknown origin, with read to 0xffff8b2a92ef2042 of 2 bytes by interrupt on cpu 1:
[ 109.306934] virtqueue_enable_cb_delayed_split+0x10f/0x170
[ 109.312880] virtqueue_enable_cb_delayed+0x3b/0x70
[ 109.318852] start_xmit+0x315/0x860 [virtio_net]
[ 109.324532] dev_hard_start_xmit+0x85/0x380
[ 109.329993] sch_direct_xmit+0xd3/0x680
[ 109.335360] __dev_xmit_skb+0x4ee/0xcc0
[ 109.340568] __dev_queue_xmit+0x560/0xe00
[ 109.345701] ip_finish_output2+0x49a/0x9b0
[ 109.350743] __ip_finish_output+0x131/0x250
[ 109.355789] ip_finish_output+0x28/0x180
[ 109.360712] ip_output+0xa0/0x1c0
[ 109.365479] __ip_queue_xmit+0x68d/0x9e0
[ 109.370156] ip_queue_xmit+0x33/0x40
[ 109.374783] __tcp_transmit_skb+0x1703/0x1970
[ 109.379467] __tcp_send_ack.part.0+0x1bb/0x320
...
[ 109.499585] do_idle+0x7a/0xe0
[ 109.502979] cpu_startup_entry+0x25/0x30
[ 109.506481] start_secondary+0x116/0x150
[ 109.509930] common_startup_64+0x13e/0x141
[ 109.516626] value changed: 0x0029 -> 0x002a
================================================================================
Add READ_ONCE() to fix the warning.
Signed-off-by: Chaohai Chen <wdhh6@aliyun.com>
---
drivers/virtio/virtio_ring.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 335692d41617..ceb026161639 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -1112,8 +1112,9 @@ static bool virtqueue_enable_cb_delayed_split(struct vring_virtqueue *vq)
&vring_used_event(&vq->split.vring),
cpu_to_virtio16(vq->vq.vdev, vq->last_used_idx + bufs));
- if (unlikely((u16)(virtio16_to_cpu(vq->vq.vdev, vq->split.vring.used->idx)
- - vq->last_used_idx) > bufs)) {
+ if (unlikely((u16)(virtio16_to_cpu(vq->vq.vdev,
+ READ_ONCE(vq->split.vring.used->idx))
+ - vq->last_used_idx) > bufs)) {
END_USE(vq);
return false;
}
--
2.43.0
next reply other threads:[~2026-03-11 17:05 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-11 17:05 Chaohai Chen [this message]
2026-03-12 2:41 ` [PATCH v3] virtio_ring: Fix KCSAN warnings in virtqueue_enable_cb_delayed_split() Jason Wang
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