Re: [PATCH net 2/2] virtio_net: fix missing lock protection on control_buf access
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2024-05-28 15:46:38
Also in:
virtualization
On Tue, May 28, 2024 at 03:52:26PM +0800, Heng Qi wrote:
Refactored the handling of control_buf to be within the cvq_lock
critical section, mitigating race conditions between reading device
responses and new command submissions.
Fixes: 6f45ab3e0409 ("virtio_net: Add a lock for the command VQ.")
Signed-off-by: Heng Qi <redacted>I don't get what does this change. status can change immediately after you drop the mutex, can it not? what exactly is the race conditions you are worried about?
quoted hunk ↗ jump to hunk
--- drivers/net/virtio_net.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 6b0512a628e0..3d8407d9e3d2 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c@@ -2686,6 +2686,7 @@ static bool virtnet_send_command_reply(struct virtnet_info *vi, u8 class, u8 cmd { struct scatterlist *sgs[5], hdr, stat; u32 out_num = 0, tmp, in_num = 0; + bool ret; int err; /* Caller should know better */@@ -2731,8 +2732,9 @@ static bool virtnet_send_command_reply(struct virtnet_info *vi, u8 class, u8 cmd } unlock: + ret = vi->ctrl->status == VIRTIO_NET_OK; mutex_unlock(&vi->cvq_lock); - return vi->ctrl->status == VIRTIO_NET_OK; + return ret; } static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,-- 2.32.0.3.g01195cf9f