On Wed, Feb 12, 2025 at 7:34 PM Breno Leitao <leitao@xxxxxxxxxx> wrote:
>
> The netdevsim driver was getting NOHZ tick-stop errors during packet
> transmission due to pending softirq work when calling napi_schedule().
>
> This is showing the following message when running netconsole selftest.
>
> NOHZ tick-stop error: local softirq work is pending, handler #08!!!
>
> Add local_bh_disable()/enable() around the napi_schedule() call to
> prevent softirqs from being handled during this xmit.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 3762ec05a9fb ("netdevsim: add NAPI support")
> Suggested-by: Jakub Kicinski <kuba@xxxxxxxxxx>
> Signed-off-by: Breno Leitao <leitao@xxxxxxxxxx>
> ---
> drivers/net/netdevsim/netdev.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/net/netdevsim/netdev.c b/drivers/net/netdevsim/netdev.c
> index 42f247cbdceecbadf27f7090c030aa5bd240c18a..6aeb081b06da226ab91c49f53d08f465570877ae 100644
> --- a/drivers/net/netdevsim/netdev.c
> +++ b/drivers/net/netdevsim/netdev.c
> @@ -87,7 +87,9 @@ static netdev_tx_t nsim_start_xmit(struct sk_buff *skb, struct net_device *dev)
> if (unlikely(nsim_forward_skb(peer_dev, skb, rq) == NET_RX_DROP))
> goto out_drop_cnt;
>
> + local_bh_disable();
> napi_schedule(&rq->napi);
> + local_bh_enable();
>
I thought all ndo_start_xmit() were done under local_bh_disable()
Could you give more details ?
