Patch 14 wires live ethtool -L rx. This patch completes the down-path
publish/rollback and get_channels() once mq_fallback is set.

When down: set TX queues first, then publish the desired RX count in
adapter->num_rx_queues and netdev->real_num_rx_queues (rx-N sysfs and
CMO desired change immediately). Do not allocate RX mappings, buffers
or IRQs while down. If RX set_real fails, restore the old TX real_num.

When up: resize RX, then the existing TX LTB
stop/alloc/set_real_num_tx/free/wake path. Skip that path when the TX
count is unchanged. If TX cannot reach the requested count, roll RX
back; that rollback is best-effort.

Validate tx_count before touching RX so a request the driver will
reject does not resize RX first. The ethtool core already range-checks
against the max_tx get_channels() reports; this is the driver's own
guard.

get_channels() always reports the live rx_count. When mq_fallback is
set it caps max_rx at that count. Understating rx_count would turn a
TX-only ethtool -L into a silent RX shrink. Capping max_rx blocks
growth in the core without misreporting what is configured.

i = old_tx before the TX alloc loop is readability; the old
for-initializer already defined i for the free walk.

Guard poll_controller() with adapter->opened so netpoll cannot walk
unallocated queue state while closed.

Signed-off-by: Mingming Cao <[email protected]>
Reviewed-by: Dave Marquardt <[email protected]>
Tested-by: Shaik Abdulla <[email protected]>
---

Changes in v6:
- get_channels() caps max_rx at the live rx_count when mq_fallback
  is set; rx_count stays live
- roll back TX real_num if down-path RX set_real fails
- poll_controller() returns if !opened
- noted: rx > 1 reject once mq_fallback is set is patch 14

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 | 143 +++++++++++++++++++++++------
 1 file changed, 117 insertions(+), 26 deletions(-)

diff --git a/drivers/net/ethernet/ibm/ibmveth.c 
b/drivers/net/ethernet/ibm/ibmveth.c
index 5aef8a1f2c23..4cd00ff3d43e 100644
--- a/drivers/net/ethernet/ibm/ibmveth.c
+++ b/drivers/net/ethernet/ibm/ibmveth.c
@@ -3156,15 +3156,24 @@ static void ibmveth_get_channels(struct net_device 
*netdev,
                                 struct ethtool_channels *channels)
 {
        struct ibmveth_adapter *adapter = netdev_priv(netdev);
+       unsigned int rx_count = ibmveth_get_num_rx_queues(adapter);
 
        channels->max_tx = ibmveth_real_max_tx_queues();
        channels->tx_count = netdev->real_num_tx_queues;
 
-       if (adapter->multi_queue)
+       /*
+        * Always report the live RX count. ethtool -L is read-modify-
+        * write, so a TX-only request echoes rx_count back at us; an
+        * understated value would be applied as a silent RX shrink.
+        * mq_fallback instead caps max_rx at the live count, which
+        * blocks growth in the core without misreporting what is
+        * currently configured.
+        */
+       channels->rx_count = rx_count;
+       if (adapter->multi_queue && !adapter->mq_fallback)
                channels->max_rx = IBMVETH_MAX_RX_QUEUES;
        else
-               channels->max_rx = 1;
-       channels->rx_count = ibmveth_get_num_rx_queues(adapter);
+               channels->max_rx = rx_count;
 }
 
 /**
@@ -3233,28 +3242,83 @@ 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;
+       bool rx_changed = false;
        int rc, i;
 
-       /* Validate RX (and resize when opened) before the down-path
-        * early return so MQ/range errors are reported here. Publishing
-        * the desired RX count and CMO while down is the next 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), publish desired queue counts without
+        * allocating.
+        */
+       if (!adapter->opened) {
+               /* Apply TX first so a failure leaves the published RX
+                * count unchanged.
+                */
+               rc = netif_set_real_num_tx_queues(netdev, goal_tx);
+               if (rc)
+                       return rc;
+
+               /* Publish desired RX count for next open() and refresh CMO;
+                * do not allocate while down.
+                */
+               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) {
+                               int tx_rc;
+
+                               ibmveth_publish_num_rx_queues(adapter, old_rx);
+                               tx_rc = netif_set_real_num_tx_queues(netdev,
+                                                                    old_tx);
+                               if (tx_rc)
+                                       netdev_err(netdev,
+                                                  "Failed to restore TX queues 
to %u after RX failure: %d\n",
+                                                  old_tx, tx_rc);
+                               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;
 
@@ -3263,28 +3327,50 @@ 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) {
+                       /*
+                        * Only meaningful once RX is live. num_slots is
+                        * embedded in the adapter and outlives the DMA ring,
+                        * so reading it at function entry is safe but can
+                        * return a stale geometry from before the resize.
+                        */
+                       int rxq_entries = adapter->rx_queue[0].num_slots;
+                       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 = {
@@ -3951,9 +4037,14 @@ static int ibmveth_change_mtu(struct net_device *dev, 
int new_mtu)
 static void ibmveth_poll_controller(struct net_device *dev)
 {
        struct ibmveth_adapter *adapter = netdev_priv(dev);
-       unsigned int num = ibmveth_get_num_rx_queues(adapter);
+       unsigned int num;
        int i;
 
+       if (!adapter->opened)
+               return;
+
+       num = ibmveth_get_num_rx_queues(adapter);
+
        for (i = 0; i < num; i++)
                ibmveth_replenish_task(adapter, i);
 
-- 
2.50.1 (Apple Git-155)


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