Hello,
+CC netdev mailing-list
On 18.8.2020 23.12, Antonio Quartulli wrote:
Hi,
On 18/08/2020 16:46, Jussi Kivilinna wrote:
batadv_bla_send_claim() gets called from worker thread context through batadv_bla_periodic_work(), thus netif_rx_ni needs to be used in that case. This fixes "NOHZ: local_softirq_pending 08" log messages seen when batman-adv is enabled.
Signed-off-by: Jussi Kivilinna jussi.kivilinna@haltian.com
net/batman-adv/bridge_loop_avoidance.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c index 5c41cc52bc53..ab6cec3c7586 100644 --- a/net/batman-adv/bridge_loop_avoidance.c +++ b/net/batman-adv/bridge_loop_avoidance.c @@ -437,7 +437,10 @@ static void batadv_bla_send_claim(struct batadv_priv *bat_priv, u8 *mac, batadv_add_counter(bat_priv, BATADV_CNT_RX_BYTES, skb->len + ETH_HLEN);
- netif_rx(skb);
- if (in_interrupt())
netif_rx(skb);- else
netif_rx_ni(skb);What's the downside in calling netif_rx_ni() all the times? Is there any possible side effect? (consider this call is not along the fast path)
Good question. I tried to find answer for this but found documentation being lacking on the issue, so I looked for examples and used 'in_interrupt/netif_rx/netif_rx_ni' bit that appears in few other places: https://elixir.bootlin.com/linux/v5.8/source/drivers/net/caif/caif_hsi.c#L46... https://elixir.bootlin.com/linux/v5.8/source/drivers/net/wireless/broadcom/b... https://elixir.bootlin.com/linux/v5.8/source/drivers/net/wireless/marvell/li... https://elixir.bootlin.com/linux/v5.8/source/drivers/net/wireless/marvell/mw... https://elixir.bootlin.com/linux/v5.8/source/net/caif/chnl_net.c#L121
Maybe someone on netdev mailing-list could give hint on this matter - should 'in_interrupt()?netif_rx(skb):netif_rx_ni(skb)' be used if context is not known or is just using 'netif_rx_ni(skb)' ok?
On top of that, I just checked the definition of in_interrupt() and I got this comment:
- Note: due to the BH disabled confusion: in_softirq(),in_interrupt()
really
should not be used in new code.Check https://elixir.bootlin.com/linux/latest/source/include/linux/preempt.h#L85
Is that something we should consider or is the comment bogus?
It very well be that the existing code that I looked at may not be the best for reuse today.
-Jussi