[PATCH net-next v5 14/19] net: stmmac: use the tracked datapath restart for XSK pool changes

[James Hilliard <james.hilliard1@gmail.com>]

Replace the void per-queue enable helpers with the tracked XDP restart.
Pause all queues and MAC link resolution while the pool bitmap and rings
change, leaving the PHY running through phylink replay.

Unwind a failed pool attachment without leaving NAPI over missing
buffers. Pool removal must complete even if ordinary-ring rebuilding
fails, after retiring all references to the departing pool. Preserve TBS
configuration and return a detached interface to the ordinary down/up
recovery path.

Fixes: bba2556efad6 ("net: stmmac: Enable RX via AF_XDP zero-copy")
Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac.h      |   5 -
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 116 +++-------------------
 drivers/net/ethernet/stmicro/stmmac/stmmac_xdp.c  |  44 ++++----
 3 files changed, 32 insertions(+), 133 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
index 6927afd01175..38370f2cbe87 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
@@ -473,11 +473,6 @@ static inline bool stmmac_tc_active(struct stmmac_priv *priv)
 	       netif_device_present(priv->dev) && !priv->hw_unavailable;
 }
 
-void stmmac_disable_rx_queue(struct stmmac_priv *priv, u32 queue);
-void stmmac_enable_rx_queue(struct stmmac_priv *priv, u32 queue);
-void stmmac_disable_tx_queue(struct stmmac_priv *priv, u32 queue);
-void stmmac_enable_tx_queue(struct stmmac_priv *priv, u32 queue);
-int stmmac_xsk_wakeup(struct net_device *dev, u32 queue, u32 flags);
 struct timespec64 stmmac_calc_tas_basetime(ktime_t old_base_time,
 					   ktime_t current_time,
 					   u64 cycle_time);
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index ad5ed2c95af7..95757f3cbc64 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -2318,6 +2318,7 @@ static void __free_dma_tx_desc_resources(struct stmmac_priv *priv,
 
 	kfree(tx_q->tx_skbuff);
 	tx_q->tx_skbuff = NULL;
+	tx_q->xsk_pool = NULL;
 }
 
 static void free_dma_tx_desc_resources(struct stmmac_priv *priv,
@@ -2830,6 +2831,12 @@ static bool stmmac_xdp_xmit_zc(struct stmmac_priv *priv, u32 queue, u32 budget)
 	bool work_done = true;
 	u32 tx_set_ic_bit = 0;
 
+	/* Nothing can be submitted while the link is down. Let NAPI complete;
+	 * userspace can retry ndo_xsk_wakeup() once carrier has returned.
+	 */
+	if (!netif_carrier_ok(priv->dev))
+		return true;
+
 	/* Avoids TX time-out as we are sharing with slow path */
 	txq_trans_cond_update(nq);
 
@@ -2844,8 +2851,7 @@ static bool stmmac_xdp_xmit_zc(struct stmmac_priv *priv, u32 queue, u32 budget)
 		/* We are sharing with slow path and stop XSK TX desc submission when
 		 * available TX ring is less than threshold.
 		 */
-		if (unlikely(stmmac_tx_avail(priv, queue) < STMMAC_TX_XSK_AVAIL) ||
-		    !netif_carrier_ok(priv->dev)) {
+		if (unlikely(stmmac_tx_avail(priv, queue) < STMMAC_TX_XSK_AVAIL)) {
 			work_done = false;
 			break;
 		}
@@ -7450,107 +7456,6 @@ static int stmmac_xdp_xmit(struct net_device *dev, int num_frames,
 	return nxmit;
 }
 
-void stmmac_disable_rx_queue(struct stmmac_priv *priv, u32 queue)
-{
-	struct stmmac_channel *ch = &priv->channel[queue];
-	unsigned long flags;
-
-	spin_lock_irqsave(&ch->lock, flags);
-	stmmac_disable_dma_irq(priv, priv->ioaddr, queue, 1, 0);
-	spin_unlock_irqrestore(&ch->lock, flags);
-
-	stmmac_stop_rx_dma(priv, queue);
-	__free_dma_rx_desc_resources(priv, priv->dma_conf, queue);
-}
-
-void stmmac_enable_rx_queue(struct stmmac_priv *priv, u32 queue)
-{
-	struct stmmac_rx_queue *rx_q = &priv->dma_conf->rx_queue[queue];
-	struct stmmac_channel *ch = &priv->channel[queue];
-	unsigned long flags;
-	int ret;
-
-	ret = __alloc_dma_rx_desc_resources(priv, priv->dma_conf, queue);
-	if (ret) {
-		netdev_err(priv->dev, "Failed to alloc RX desc.\n");
-		return;
-	}
-
-	ret = __init_dma_rx_desc_rings(priv, priv->dma_conf, queue, GFP_KERNEL);
-	if (ret) {
-		__free_dma_rx_desc_resources(priv, priv->dma_conf, queue);
-		netdev_err(priv->dev, "Failed to init RX desc.\n");
-		return;
-	}
-
-	stmmac_reset_rx_queue(priv, queue);
-	stmmac_clear_rx_descriptors(priv, priv->dma_conf, queue);
-
-	stmmac_init_rx_chan(priv, priv->ioaddr, priv->plat->dma_cfg,
-			    rx_q->dma_rx_phy, queue);
-
-	stmmac_set_queue_rx_tail_ptr(priv, rx_q, queue, rx_q->buf_alloc_num);
-
-	stmmac_set_queue_rx_buf_size(priv, rx_q, queue);
-
-	stmmac_start_rx_dma(priv, queue);
-
-	spin_lock_irqsave(&ch->lock, flags);
-	stmmac_enable_dma_irq(priv, priv->ioaddr, queue, 1, 0);
-	spin_unlock_irqrestore(&ch->lock, flags);
-}
-
-void stmmac_disable_tx_queue(struct stmmac_priv *priv, u32 queue)
-{
-	struct stmmac_channel *ch = &priv->channel[queue];
-	unsigned long flags;
-
-	spin_lock_irqsave(&ch->lock, flags);
-	stmmac_disable_dma_irq(priv, priv->ioaddr, queue, 0, 1);
-	spin_unlock_irqrestore(&ch->lock, flags);
-
-	stmmac_stop_tx_dma(priv, queue);
-	__free_dma_tx_desc_resources(priv, priv->dma_conf, queue);
-}
-
-void stmmac_enable_tx_queue(struct stmmac_priv *priv, u32 queue)
-{
-	struct stmmac_tx_queue *tx_q = &priv->dma_conf->tx_queue[queue];
-	struct stmmac_channel *ch = &priv->channel[queue];
-	unsigned long flags;
-	int ret;
-
-	ret = __alloc_dma_tx_desc_resources(priv, priv->dma_conf, queue);
-	if (ret) {
-		netdev_err(priv->dev, "Failed to alloc TX desc.\n");
-		return;
-	}
-
-	ret = __init_dma_tx_desc_rings(priv,  priv->dma_conf, queue);
-	if (ret) {
-		__free_dma_tx_desc_resources(priv, priv->dma_conf, queue);
-		netdev_err(priv->dev, "Failed to init TX desc.\n");
-		return;
-	}
-
-	stmmac_reset_tx_queue(priv, queue);
-	stmmac_clear_tx_descriptors(priv, priv->dma_conf, queue);
-
-	stmmac_init_tx_chan(priv, priv->ioaddr, priv->plat->dma_cfg,
-			    tx_q->dma_tx_phy, queue);
-
-	if (tx_q->tbs & STMMAC_TBS_AVAIL)
-		stmmac_enable_tbs(priv, priv->ioaddr, 1, queue);
-
-	stmmac_set_queue_tx_tail_ptr(priv, tx_q, queue, 0);
-
-	stmmac_start_tx_dma(priv, queue);
-
-	spin_lock_irqsave(&ch->lock, flags);
-	stmmac_enable_dma_irq(priv, priv->ioaddr, queue, 0, 1);
-	spin_unlock_irqrestore(&ch->lock, flags);
-}
-
 void stmmac_xdp_release(struct net_device *dev)
 {
 	struct stmmac_priv *priv = netdev_priv(dev);
@@ -7650,6 +7555,9 @@ int stmmac_xdp_open(struct net_device *dev)
 
 		stmmac_set_queue_tx_tail_ptr(priv, tx_q, chan, 0);
 
+		if (tx_q->tbs & STMMAC_TBS_AVAIL)
+			stmmac_enable_tbs(priv, priv->ioaddr, 1, chan);
+
 		hrtimer_setup(&tx_q->txtimer, stmmac_tx_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 	}
 
@@ -7687,7 +7595,7 @@ int stmmac_xdp_open(struct net_device *dev)
 	return ret;
 }
 
-int stmmac_xsk_wakeup(struct net_device *dev, u32 queue, u32 flags)
+static int stmmac_xsk_wakeup(struct net_device *dev, u32 queue, u32 flags)
 {
 	struct stmmac_priv *priv = netdev_priv(dev);
 	struct stmmac_channel *ch;
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_xdp.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_xdp.c
index 7ecb7addd2ea..907ac49a1b76 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_xdp.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_xdp.c
@@ -9,7 +9,6 @@
 static int stmmac_xdp_enable_pool(struct stmmac_priv *priv,
 				  struct xsk_buff_pool *pool, u16 queue)
 {
-	struct stmmac_channel *ch = &priv->channel[queue];
 	bool need_update;
 	u32 frame_size;
 	int err;
@@ -34,23 +33,23 @@ static int stmmac_xdp_enable_pool(struct stmmac_priv *priv,
 	need_update = priv->datapath == STMMAC_DATAPATH_RUNNING &&
 		      stmmac_xdp_is_enabled(priv);
 
-	if (need_update) {
-		napi_disable(&ch->rx_napi);
-		napi_disable(&ch->tx_napi);
-		stmmac_disable_rx_queue(priv, queue);
-		stmmac_disable_tx_queue(priv, queue);
-	}
+	if (need_update)
+		stmmac_xdp_release(priv->dev);
 
 	set_bit(queue, priv->af_xdp_zc_qps);
 
 	if (need_update) {
-		stmmac_enable_rx_queue(priv, queue);
-		stmmac_enable_tx_queue(priv, queue);
-		napi_enable(&ch->rxtx_napi);
-
-		err = stmmac_xsk_wakeup(priv->dev, queue, XDP_WAKEUP_RX);
-		if (err)
+		err = stmmac_xdp_open(priv->dev);
+		if (err) {
+			clear_bit(queue, priv->af_xdp_zc_qps);
+			xsk_pool_dma_unmap(pool, STMMAC_RX_DMA_ATTR);
+			netdev_err(priv->dev, "failed reopening after XSK pool attach: %pe; interface remains detached\n",
+				   ERR_PTR(err));
 			return err;
+		}
+
+		/* The pool is installed even if link resolution is still pending. */
+		napi_schedule(&priv->channel[queue].rxtx_napi);
 	}
 
 	return 0;
@@ -58,9 +57,9 @@ static int stmmac_xdp_enable_pool(struct stmmac_priv *priv,
 
 static int stmmac_xdp_disable_pool(struct stmmac_priv *priv, u16 queue)
 {
-	struct stmmac_channel *ch = &priv->channel[queue];
 	struct xsk_buff_pool *pool;
 	bool need_update;
+	int err;
 
 	if (queue >= priv->plat->rx_queues_to_use ||
 	    queue >= priv->plat->tx_queues_to_use)
@@ -73,24 +72,21 @@ static int stmmac_xdp_disable_pool(struct stmmac_priv *priv, u16 queue)
 	need_update = priv->datapath == STMMAC_DATAPATH_RUNNING &&
 		      stmmac_xdp_is_enabled(priv);
 
-	if (need_update) {
-		napi_disable(&ch->rxtx_napi);
-		stmmac_disable_rx_queue(priv, queue);
-		stmmac_disable_tx_queue(priv, queue);
-		synchronize_rcu();
-	}
+	if (need_update)
+		stmmac_xdp_release(priv->dev);
 
 	xsk_pool_dma_unmap(pool, STMMAC_RX_DMA_ATTR);
 
 	clear_bit(queue, priv->af_xdp_zc_qps);
 
 	if (need_update) {
-		stmmac_enable_rx_queue(priv, queue);
-		stmmac_enable_tx_queue(priv, queue);
-		napi_enable(&ch->rx_napi);
-		napi_enable(&ch->tx_napi);
+		err = stmmac_xdp_open(priv->dev);
+		if (err)
+			netdev_err(priv->dev, "failed reopening after XSK pool removal: %pe; interface remains detached\n",
+				   ERR_PTR(err));
 	}
 
+	/* Socket teardown must be able to unmap and free the removed pool. */
 	return 0;
 }
 

-- 
2.53.0