From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Mao Wenan <wenan.mao@linux.alibaba.com>,
"Michael S . Tsirkin" <mst@redhat.com>,
Jason Wang <jasowang@redhat.com>, Sasha Levin <sashal@kernel.org>,
virtualization@lists.linux-foundation.org
Subject: [PATCH AUTOSEL 4.9 09/11] virtio_ring: Avoid loop when vq is broken in virtqueue_poll
Date: Wed, 19 Aug 2020 20:03:46 -0400 [thread overview]
Message-ID: <20200820000348.215911-9-sashal@kernel.org> (raw)
In-Reply-To: <20200820000348.215911-1-sashal@kernel.org>
From: Mao Wenan <wenan.mao@linux.alibaba.com>
[ Upstream commit 481a0d7422db26fb63e2d64f0652667a5c6d0f3e ]
The loop may exist if vq->broken is true,
virtqueue_get_buf_ctx_packed or virtqueue_get_buf_ctx_split
will return NULL, so virtnet_poll will reschedule napi to
receive packet, it will lead cpu usage(si) to 100%.
call trace as below:
virtnet_poll
virtnet_receive
virtqueue_get_buf_ctx
virtqueue_get_buf_ctx_packed
virtqueue_get_buf_ctx_split
virtqueue_napi_complete
virtqueue_poll //return true
virtqueue_napi_schedule //it will reschedule napi
to fix this, return false if vq is broken in virtqueue_poll.
Signed-off-by: Mao Wenan <wenan.mao@linux.alibaba.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Link: https://lore.kernel.org/r/1596354249-96204-1-git-send-email-wenan.mao@linux.alibaba.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/virtio/virtio_ring.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index e459cd7302e27..5cad9f41c238b 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -785,6 +785,9 @@ bool virtqueue_poll(struct virtqueue *_vq, unsigned last_used_idx)
{
struct vring_virtqueue *vq = to_vvq(_vq);
+ if (unlikely(vq->broken))
+ return false;
+
virtio_mb(vq->weak_barriers);
return (u16)last_used_idx != virtio16_to_cpu(_vq->vdev, vq->vring.used->idx);
}
--
2.25.1
next prev parent reply other threads:[~2020-08-20 0:05 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-20 0:03 [PATCH AUTOSEL 4.9 01/11] scsi: ufs: Add DELAY_BEFORE_LPM quirk for Micron devices Sasha Levin
2020-08-20 0:03 ` [PATCH AUTOSEL 4.9 02/11] media: budget-core: Improve exception handling in budget_register() Sasha Levin
2020-08-20 0:03 ` [PATCH AUTOSEL 4.9 03/11] media: vpss: clean up resources in init Sasha Levin
2020-08-20 0:03 ` [PATCH AUTOSEL 4.9 04/11] Input: psmouse - add a newline when printing 'proto' by sysfs Sasha Levin
2020-08-20 0:03 ` [PATCH AUTOSEL 4.9 05/11] m68knommu: fix overwriting of bits in ColdFire V3 cache control Sasha Levin
2020-08-20 0:03 ` [PATCH AUTOSEL 4.9 06/11] xfs: fix inode quota reservation checks Sasha Levin
2020-08-20 0:03 ` [PATCH AUTOSEL 4.9 07/11] jffs2: fix UAF problem Sasha Levin
2020-08-20 0:03 ` [PATCH AUTOSEL 4.9 08/11] scsi: libfc: Free skb in fc_disc_gpn_id_resp() for valid cases Sasha Levin
2020-08-20 0:03 ` Sasha Levin [this message]
2020-08-20 0:03 ` [PATCH AUTOSEL 4.9 10/11] xfs: Fix UBSAN null-ptr-deref in xfs_sysfs_init Sasha Levin
2020-08-20 0:03 ` [PATCH AUTOSEL 4.9 11/11] alpha: fix annotation of io{read,write}{16,32}be() Sasha Levin
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