[PATCH net-next v5 15/15] ibmveth: Wire ethtool set_channels to MQ RX queue resize

[Mingming Cao <mmc@linux.ibm.com>]

Complete set_channels() RX handling around ibmveth_resize_rx_channels():

  - When down: set TX queues first, then stash the desired RX count
    in adapter->num_rx_queues for the next open() (open publishes via
    netif_set_real_num_rx_queues). There are no RX mappings/buffers/IRQs
    to grow or shrink while down, so do not allocate immediately.
  - When up: resize RX, then adjust TX LTBs with the existing
    stop/alloc/set_real_num_tx/free/wake path.
  - Skip TX stop/wake when the TX count is unchanged.

Make TX/RX updates fail atomically: validate both ranges up front;
apply TX before stashing RX while down; when up, roll RX back if TX
cannot reach the requested count. Initialize the TX alloc loop bound
so a scale-down path that never allocates still has defined cleanup
if set_real_num_tx_queues() fails.

Gate live RX resize on adapter->opened (not IFF_UP): RX resources
exist only after a successful open, matching the while-down stash path.

Signed-off-by: Mingming Cao <mmc@linux.ibm.com>
Reviewed-by: Dave Marquardt <davemarq@linux.ibm.com>
Tested-by: Shaik Abdulla <shaik.abdulla1@ibm.com>
---

Changes in v5:
- set_channels / resize_rx_channels read via get_num_rx_queues()
- Series renumber: mailed v4 13/14 set_channels -> tip P15 (end; 14->15)
- set_channels: gate on adapter->opened (not IFF_UP) for live RX resize
  vs while-down stash
- Down-path RX stash also refreshes CMO (publish + set_real_num_rx)
- When up: resize RX then TX; roll RX back if TX cannot reach goal

Changes in v4:
- On !IFF_UP, stash num_rx_queues only after TX set succeeds; do not
  allocate live subordinate IRQs/buffers while down.
- Initialize i = old_tx on the TX adjust path.
- Always return rc from set_channels().
- Split from the resize-helper patch (same split as v3) while keeping
  a live caller of resize_rx_channels() in the previous patch.

 drivers/net/ethernet/ibm/ibmveth.c | 107 +++++++++++++++++++++++------
 1 file changed, 85 insertions(+), 22 deletions(-)

diff --git a/drivers/net/ethernet/ibm/ibmveth.c b/drivers/net/ethernet/ibm/ibmveth.c
index 84f4a0deb0c5..35cbd2553e86 100644
--- a/drivers/net/ethernet/ibm/ibmveth.c
+++ b/drivers/net/ethernet/ibm/ibmveth.c
@@ -800,6 +800,7 @@ ibmveth_kick_rx_queue_if_pending(struct ibmveth_adapter *adapter,
 	if (ibmveth_rxq_pending_buffer(adapter, queue_index))
 		ibmveth_schedule_rx_queue(adapter, queue_index);
 }
+
 /* setup the initial settings for a buffer pool */
 static void ibmveth_init_buffer_pool(struct ibmveth_buff_pool *pool,
 				     u32 pool_index, u32 pool_size,
@@ -3175,28 +3176,75 @@ static int ibmveth_set_channels(struct net_device *netdev,
 				struct ethtool_channels *channels)
 {
 	struct ibmveth_adapter *adapter = netdev_priv(netdev);
-	unsigned int old = netdev->real_num_tx_queues,
-		     goal = channels->tx_count;
+	unsigned int old_rx = ibmveth_get_num_rx_queues(adapter);
+	unsigned int goal_rx = channels->rx_count;
+	unsigned int old_tx = netdev->real_num_tx_queues;
+	unsigned int goal_tx = channels->tx_count;
+	unsigned int want_tx = goal_tx;
+	int rxq_entries = adapter->rx_queue[0].num_slots;
+	bool rx_changed = false;
 	int rc, i;
 
-	/* Validate RX (and resize when opened) before the down-path early
-	 * return so MQ/range errors are not deferred to the wiring patch.
-	 * RX stash + CMO while down still lands with that patch.
-	 */
-	rc = ibmveth_resize_rx_channels(adapter, channels->rx_count);
+	if (goal_tx < 1 || goal_tx > ibmveth_real_max_tx_queues()) {
+		netdev_err(netdev,
+			   "Invalid TX queue count %u (must be 1-%u)\n",
+			   goal_tx, ibmveth_real_max_tx_queues());
+		return -EINVAL;
+	}
+
+	/* RX range / MQ checks live in ibmveth_resize_rx_channels(). */
+	rc = ibmveth_resize_rx_channels(adapter, goal_rx);
 	if (rc)
 		return rc;
 
-	if (!adapter->opened)
-		return netif_set_real_num_tx_queues(netdev, goal);
+	/* If RX resources are not live (never opened, or close+open failed
+	 * while IFF_UP stayed set), only stash desired queue counts.
+	 */
+	if (!adapter->opened) {
+		/* Apply TX first so a failure leaves RX stash unchanged. */
+		rc = netif_set_real_num_tx_queues(netdev, goal_tx);
+		if (rc)
+			return rc;
+
+		/* Stash desired RX count; open() publishes it via
+		 * netif_set_real_num_rx_queues() after queue registration.
+		 * Refresh CMO now so open() can map the larger footprint;
+		 * open itself does not call vio_cmo_set_dev_desired.
+		 */
+		if (goal_rx != ibmveth_get_num_rx_queues(adapter)) {
+			ibmveth_publish_num_rx_queues(adapter, goal_rx);
+			rc = netif_set_real_num_rx_queues(netdev, goal_rx);
+			if (rc) {
+				ibmveth_publish_num_rx_queues(adapter, old_rx);
+				return rc;
+			}
+			if (firmware_has_feature(FW_FEATURE_CMO)) {
+				unsigned long dma;
+
+				dma = ibmveth_get_desired_dma(adapter->vdev);
+				vio_cmo_set_dev_desired(adapter->vdev, dma);
+			}
+		}
+		return 0;
+	}
+
+	if (goal_rx != old_rx)
+		rx_changed = true;
 
 	/* We have IBMVETH_MAX_QUEUES netdev_queue's allocated
 	 * but we may need to alloc/free the ltb's.
 	 */
+	if (goal_tx == old_tx)
+		return 0;
+
 	netif_tx_stop_all_queues(netdev);
 
-	/* Allocate any queue that we need */
-	for (i = old; i < goal; i++) {
+	/* Allocate any new TX LTBs. i starts at old_tx for the free walk
+	 * below when this loop body never runs (goal_tx == old_tx already
+	 * returned; goal_tx < old_tx is scale-down).
+	 */
+	i = old_tx;
+	for (; i < goal_tx; i++) {
 		if (adapter->tx_ltb_ptr[i])
 			continue;
 
@@ -3205,28 +3253,43 @@ static int ibmveth_set_channels(struct net_device *netdev,
 			continue;
 
 		/* if something goes wrong, free everything we just allocated */
-		netdev_err(netdev, "Failed to allocate more tx queues, returning to %d queues\n",
-			   old);
-		goal = old;
-		old = i;
+		netdev_err(netdev, "Failed to allocate more tx queues, returning to %u queues\n",
+			   old_tx);
+		goal_tx = old_tx;
+		old_tx = i;
 		break;
 	}
-	rc = netif_set_real_num_tx_queues(netdev, goal);
+	rc = netif_set_real_num_tx_queues(netdev, goal_tx);
 	if (rc) {
-		netdev_err(netdev, "Failed to set real tx queues, returning to %d queues\n",
-			   old);
-		goal = old;
-		old = i;
+		netdev_err(netdev, "Failed to set real tx queues, returning to %u queues\n",
+			   old_tx);
+		goal_tx = old_tx;
+		old_tx = i;
 	}
 	/* Free any that are no longer needed */
-	for (i = old; i > goal; i--) {
+	for (i = old_tx; i > goal_tx; i--) {
 		if (adapter->tx_ltb_ptr[i - 1])
 			ibmveth_free_tx_ltb(adapter, i - 1);
 	}
 
 	netif_tx_wake_all_queues(netdev);
 
-	return rc;
+	if (netdev->real_num_tx_queues != want_tx) {
+		if (rx_changed) {
+			int rb;
+
+			rb = ibmveth_resize_rx_queues_incremental(adapter,
+								  old_rx,
+								  rxq_entries);
+			if (rb)
+				netdev_err(netdev,
+					   "Failed to roll back RX queues to %u after TX failure: %d\n",
+					   old_rx, rb);
+		}
+		return rc ? rc : -ENOMEM;
+	}
+
+	return 0;
 }
 
 static const struct ethtool_ops netdev_ethtool_ops = {
-- 
2.50.1 (Apple Git-155)