sfc: Remove ancient support for nesting of TX stop

Long before this driver went into mainline, it had support for
multiple TX queues per port, with lockless TX enabled.  Since Linux
did not know anything of this, filling up any hardware TX queue would
stop the core TX queue and multiple hardware TX queues could fill up
before the scheduler reacted.  Thus it was necessary to keep a count
of how many TX queues were stopped and to wake the core TX queue only
when all had free space again.

The driver also previously (ab)used the per-hardware-queue stopped
flag as a counter to deal with various things that can inhibit TX, but
it no longer does that.

Remove the per-channel tx_stop_count, tx_stop_lock and
per-hardware-queue stopped count and just use the networking core
queue state directly.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>

1 files changed, 14 insertions, 10 deletions

diff --git a/drivers/net/sfc/efx.c b/drivers/net/sfc/efx.c
index 2166c1d..711449c 100644
--- a/drivers/net/sfc/efx.c
+++ b/drivers/net/sfc/efx.c
@@ -461,9 +461,6 @@ efx_alloc_channel(struct efx_nic *efx, int i, struct efx_channel *old_channel)
 		}
 	}
 
-	spin_lock_init(&channel->tx_stop_lock);
-	atomic_set(&channel->tx_stop_count, 1);
-
 	rx_queue = &channel->rx_queue;
 	rx_queue->efx = efx;
 	setup_timer(&rx_queue->slow_fill, efx_rx_slow_fill,
@@ -1406,11 +1403,11 @@ static void efx_start_all(struct efx_nic *efx)
 	 * restart the transmit interface early so the watchdog timer stops */
 	efx_start_port(efx);
 
-	efx_for_each_channel(channel, efx) {
-		if (efx_dev_registered(efx))
-			efx_wake_queue(channel);
+	if (efx_dev_registered(efx))
+		netif_tx_wake_all_queues(efx->net_dev);
+
+	efx_for_each_channel(channel, efx)
 		efx_start_channel(channel);
-	}
 
 	if (efx->legacy_irq)
 		efx->legacy_irq_enabled = true;
@@ -1498,9 +1495,7 @@ static void efx_stop_all(struct efx_nic *efx)
 	/* Stop the kernel transmit interface late, so the watchdog
 	 * timer isn't ticking over the flush */
 	if (efx_dev_registered(efx)) {
-		struct efx_channel *channel;
-		efx_for_each_channel(channel, efx)
-			efx_stop_queue(channel);
+		netif_tx_stop_all_queues(efx->net_dev);
 		netif_tx_lock_bh(efx->net_dev);
 		netif_tx_unlock_bh(efx->net_dev);
 	}
@@ -1896,6 +1891,7 @@ static DEVICE_ATTR(phy_type, 0644, show_phy_type, NULL);
 static int efx_register_netdev(struct efx_nic *efx)
 {
 	struct net_device *net_dev = efx->net_dev;
+	struct efx_channel *channel;
 	int rc;
 
 	net_dev->watchdog_timeo = 5 * HZ;
@@ -1918,6 +1914,14 @@ static int efx_register_netdev(struct efx_nic *efx)
 	if (rc)
 		goto fail_locked;
 
+	efx_for_each_channel(channel, efx) {
+		struct efx_tx_queue *tx_queue;
+		efx_for_each_channel_tx_queue(tx_queue, channel) {
+			tx_queue->core_txq = netdev_get_tx_queue(
+				efx->net_dev, tx_queue->queue / EFX_TXQ_TYPES);
+		}
+	}
+
 	/* Always start with carrier off; PHY events will detect the link */
 	netif_carrier_off(efx->net_dev);