net: add softnet_data.in_net_rx_action

We want to make two optimizations in napi_schedule_rps() and
____napi_schedule() which require to know if these helpers are
called from net_rx_action(), instead of being called from
other contexts.

sd.in_net_rx_action is only read/written by the owning cpu.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
Tested-by: Jason Xing <kerneljasonxing@gmail.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 18a5be6..c8c6340 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3188,6 +3188,7 @@ struct softnet_data {
 #ifdef CONFIG_RPS
        struct softnet_data     *rps_ipi_list;
 #endif
+       bool                    in_net_rx_action;
 #ifdef CONFIG_NET_FLOW_LIMIT
        struct sd_flow_limit __rcu *flow_limit;
 #endif

diff --git a/net/core/dev.c b/net/core/dev.c
index f7050b9..15331ed 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6646,6 +6646,7 @@ static __latent_entropy void net_rx_action(struct softirq_action *h)
        LIST_HEAD(list);
        LIST_HEAD(repoll);
 
+       sd->in_net_rx_action = true;
        local_irq_disable();
        list_splice_init(&sd->poll_list, &list);
        local_irq_enable();
@@ -6656,6 +6657,7 @@ static __latent_entropy void net_rx_action(struct softirq_action *h)
                skb_defer_free_flush(sd);
 
                if (list_empty(&list)) {
+                       sd->in_net_rx_action = false;
                        if (!sd_has_rps_ipi_waiting(sd) && list_empty(&repoll))
                                goto end;
                        break;
@@ -6682,6 +6684,8 @@ static __latent_entropy void net_rx_action(struct softirq_action *h)
        list_splice(&list, &sd->poll_list);
        if (!list_empty(&sd->poll_list))
                __raise_softirq_irqoff(NET_RX_SOFTIRQ);
+       else
+               sd->in_net_rx_action = false;
 
        net_rps_action_and_irq_enable(sd);
 end:;