sfc: do ARFS expiry work occasionally even without NAPI poll

If there's no traffic on a channel, its ARFS expiry work will never get
 scheduled by efx_poll() as that isn't being run.
So make efx_filter_rfs_expire() reschedule itself to run after 30 seconds.
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>

drivers/net/ethernet/sfc/efx.c

@@ -355,7 +355,7 @@ static int efx_poll(struct napi_struct *napi, int budget)
 
 #ifdef CONFIG_RFS_ACCEL
 		/* Perhaps expire some ARFS filters */
-		schedule_work(&channel->filter_work);
+		mod_delayed_work(system_wq, &channel->filter_work, 0);
 #endif
 
 		/* There is no race here; although napi_disable() will
@@ -487,7 +487,7 @@ efx_alloc_channel(struct efx_nic *efx, int i, struct efx_channel *old_channel)
 	}
 
 #ifdef CONFIG_RFS_ACCEL
-	INIT_WORK(&channel->filter_work, efx_filter_rfs_expire);
+	INIT_DELAYED_WORK(&channel->filter_work, efx_filter_rfs_expire);
 #endif
 
 	rx_queue = &channel->rx_queue;
@@ -533,7 +533,7 @@ efx_copy_channel(const struct efx_channel *old_channel)
 	memset(&rx_queue->rxd, 0, sizeof(rx_queue->rxd));
 	timer_setup(&rx_queue->slow_fill, efx_rx_slow_fill, 0);
 #ifdef CONFIG_RFS_ACCEL
-	INIT_WORK(&channel->filter_work, efx_filter_rfs_expire);
+	INIT_DELAYED_WORK(&channel->filter_work, efx_filter_rfs_expire);
 #endif
 
 	return channel;
@@ -1994,7 +1994,7 @@ static void efx_remove_filters(struct efx_nic *efx)
 	struct efx_channel *channel;
 
 	efx_for_each_channel(channel, efx) {
-		flush_work(&channel->filter_work);
+		cancel_delayed_work_sync(&channel->filter_work);
 		kfree(channel->rps_flow_id);
 	}
 #endif

drivers/net/ethernet/sfc/efx.h

@@ -169,13 +169,17 @@ int efx_filter_rfs(struct net_device *net_dev, const struct sk_buff *skb,
 bool __efx_filter_rfs_expire(struct efx_channel *channel, unsigned int quota);
 static inline void efx_filter_rfs_expire(struct work_struct *data)
 {
-	struct efx_channel *channel = container_of(data, struct efx_channel,
-						   filter_work);
-	unsigned int time = jiffies - channel->rfs_last_expiry, quota;
+	struct delayed_work *dwork = to_delayed_work(data);
+	struct efx_channel *channel;
+	unsigned int time, quota;
 
+	channel = container_of(dwork, struct efx_channel, filter_work);
+	time = jiffies - channel->rfs_last_expiry;
 	quota = channel->rfs_filter_count * time / (30 * HZ);
 	if (quota > 20 && __efx_filter_rfs_expire(channel, min(channel->rfs_filter_count, quota)))
 		channel->rfs_last_expiry += time;
+	/* Ensure we do more work eventually even if NAPI poll is not happening */
+	schedule_delayed_work(dwork, 30 * HZ);
 }
 #define efx_filter_rfs_enabled() 1
 #else

drivers/net/ethernet/sfc/net_driver.h

@@ -501,7 +501,7 @@ struct efx_channel {
 	unsigned int rfs_expire_index;
 	unsigned int n_rfs_succeeded;
 	unsigned int n_rfs_failed;
-	struct work_struct filter_work;
+	struct delayed_work filter_work;
 #define RPS_FLOW_ID_INVALID 0xFFFFFFFF
 	u32 *rps_flow_id;
 #endif