Re: [PATCH net-next 1/3] virtio-net: fix possible dim status unrecoverable

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]


在 2024/1/16 下午9:15, Michael S. Tsirkin 写道:
On Tue, Jan 16, 2024 at 09:11:31PM +0800, Heng Qi wrote:
When the dim worker is scheduled, if it fails to acquire the lock,
dim may not be able to return to the working state later.

For example, the following single queue scenario:
   1. The dim worker of rxq0 is scheduled, and the dim status is
      changed to DIM_APPLY_NEW_PROFILE;
   2. The ethtool command is holding rtnl lock;
   3. Since the rtnl lock is already held, virtnet_rx_dim_work fails
      to acquire the lock and exits;

Then, even if net_dim is invoked again, it cannot work because the
state is not restored to DIM_START_MEASURE.

Fixes: 6208799553a8 ("virtio-net: support rx netdim")
Signed-off-by: Heng Qi <hengqi@xxxxxxxxxxxxxxxxx>
Belongs to the net branch.

  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 d7ce4a1..f6ac3e7 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -3524,8 +3524,10 @@ static void virtnet_rx_dim_work(struct work_struct *work)
  	struct dim_cq_moder update_moder;
  	int i, qnum, err;
- if (!rtnl_trylock())
+	if (!rtnl_trylock()) {
+		schedule_work(&dim->work);
+	}
/* Each rxq's work is queued by "net_dim()->schedule_work()"
  	 * in response to NAPI traffic changes. Note that dim->profile_ix
OK but this means that in cleanup it is not sufficient to flush
dim work - it can requeue itself.

We did not use the flush work operation, cancel_work_sync will handle the re-queue situation:

   "Cancel @work and wait for its execution to finish. This function
   can be used even if the work re-queues itself or migrates to
   another workqueue. On return from this function, @work is
   guaranteed to be not pending or executing on any CPU."



[Index of Archives]     [KVM Development]     [Libvirt Development]     [Libvirt Users]     [CentOS Virtualization]     [Netdev]     [Ethernet Bridging]     [Linux Wireless]     [Kernel Newbies]     [Security]     [Linux for Hams]     [Netfilter]     [Bugtraq]     [Yosemite Forum]     [MIPS Linux]     [ARM Linux]     [Linux RAID]     [Linux Admin]     [Samba]

  Powered by Linux