This is a note to let you know that I've just added the patch titled net: lapbether: Remove netif_start_queue / netif_stop_queue to the 5.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: net-lapbether-remove-netif_start_queue-netif_stop_queue.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From f7d9d4854519fdf4d45c70a4d953438cd88e7e58 Mon Sep 17 00:00:00 2001 From: Xie He <xie.he.0141@xxxxxxxxx> Date: Sun, 7 Mar 2021 03:33:07 -0800 Subject: net: lapbether: Remove netif_start_queue / netif_stop_queue From: Xie He <xie.he.0141@xxxxxxxxx> commit f7d9d4854519fdf4d45c70a4d953438cd88e7e58 upstream. For the devices in this driver, the default qdisc is "noqueue", because their "tx_queue_len" is 0. In function "__dev_queue_xmit" in "net/core/dev.c", devices with the "noqueue" qdisc are specially handled. Packets are transmitted without being queued after a "dev->flags & IFF_UP" check. However, it's possible that even if this check succeeds, "ops->ndo_stop" may still have already been called. This is because in "__dev_close_many", "ops->ndo_stop" is called before clearing the "IFF_UP" flag. If we call "netif_stop_queue" in "ops->ndo_stop", then it's possible in "__dev_queue_xmit", it sees the "IFF_UP" flag is present, and then it checks "netif_xmit_stopped" and finds that the queue is already stopped. In this case, it will complain that: "Virtual device ... asks to queue packet!" To prevent "__dev_queue_xmit" from generating this complaint, we should not call "netif_stop_queue" in "ops->ndo_stop". We also don't need to call "netif_start_queue" in "ops->ndo_open", because after a netdev is allocated and registered, the "__QUEUE_STATE_DRV_XOFF" flag is initially not set, so there is no need to call "netif_start_queue" to clear it. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Xie He <xie.he.0141@xxxxxxxxx> Acked-by: Martin Schiller <ms@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/net/wan/lapbether.c | 3 --- 1 file changed, 3 deletions(-) --- a/drivers/net/wan/lapbether.c +++ b/drivers/net/wan/lapbether.c @@ -283,7 +283,6 @@ static int lapbeth_open(struct net_devic return -ENODEV; } - netif_start_queue(dev); return 0; } @@ -291,8 +290,6 @@ static int lapbeth_close(struct net_devi { int err; - netif_stop_queue(dev); - if ((err = lapb_unregister(dev)) != LAPB_OK) pr_err("lapb_unregister error: %d\n", err); Patches currently in stable-queue which might be from xie.he.0141@xxxxxxxxx are queue-5.10/net-lapbether-remove-netif_start_queue-netif_stop_queue.patch