From: Long Li <[email protected]>

Carry the MTU in the queue set and size replacement RX buffers from it.
Publish ndev->mtu after RSS configuration succeeds; allocation failure
leaves the live queues and advertised MTU unchanged.

This full rebuild temporarily keeps both sets of SQ/RQ/CQ objects,
RX buffers and page pools live. The port-owned EQ pool is shared,
not doubled. Device resource limits may reject this temporary peak;
allocation failure preserves the live queues and configuration.

Reserve RAW-QP admission under vport_mutex for the entire live
replacement, including unpublished queues, fail-close and scratch
cleanup. Preserve validation, no-op and down-port behavior.

Signed-off-by: Long Li <[email protected]>
Signed-off-by: Wei Hu <[email protected]>
---
 drivers/net/ethernet/microsoft/mana/mana_en.c | 66 ++++++++++++++-----
 .../ethernet/microsoft/mana/mana_ethtool.c    | 10 +--
 include/net/mana/mana.h                       |  7 +-
 3 files changed, 60 insertions(+), 23 deletions(-)

diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c 
b/drivers/net/ethernet/microsoft/mana/mana_en.c
index 10225c09f5b7..4577a473ff42 100644
--- a/drivers/net/ethernet/microsoft/mana/mana_en.c
+++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
@@ -927,32 +927,52 @@ int mana_pre_alloc_rxbufs(struct mana_port_context *mpc, 
int new_mtu, int num_qu
 static int mana_change_mtu(struct net_device *ndev, int new_mtu)
 {
        struct mana_port_context *mpc = netdev_priv(ndev);
-       unsigned int old_mtu = ndev->mtu;
+       struct mana_port_context *scratch;
+       struct mana_qset newq, oldq;
        int err;
 
-       /* Pre-allocate buffers to prevent failure in mana_attach later */
-       err = mana_pre_alloc_rxbufs(mpc, new_mtu, mpc->num_queues);
-       if (err) {
-               netdev_err(ndev, "Insufficient memory for new MTU\n");
-               return err;
+       if (!mpc->port_is_up) {
+               mpc->configured_mtu = new_mtu;
+               WRITE_ONCE(ndev->mtu, new_mtu);
+               return 0;
        }
 
-       err = mana_detach(ndev, false);
-       if (err) {
-               netdev_err(ndev, "mana_detach failed: %d\n", err);
-               goto out;
+       /* Fail-close may release the Ethernet vport reference. */
+       mutex_lock(&mpc->vport_mutex);
+       if (mpc->channel_changing) {
+               mutex_unlock(&mpc->vport_mutex);
+               return -EBUSY;
+       }
+       mpc->channel_changing = true;
+       mutex_unlock(&mpc->vport_mutex);
+
+       scratch = mana_qset_scratch_alloc(mpc);
+       if (!scratch) {
+               err = -ENOMEM;
+               goto clear_flag;
        }
 
-       WRITE_ONCE(ndev->mtu, new_mtu);
+       err = mana_alloc_qset(mpc, scratch, mpc->num_queues,
+                             mpc->rx_queue_size, mpc->tx_queue_size,
+                             mpc->priv_flags, new_mtu, &newq);
+       if (err)
+               goto free_scratch;
 
-       err = mana_attach(ndev);
+       err = mana_publish_qset(mpc, &newq, &oldq);
        if (err) {
-               netdev_err(ndev, "mana_attach failed: %d\n", err);
-               WRITE_ONCE(ndev->mtu, old_mtu);
+               mana_free_qset(scratch, &newq);
+               goto free_scratch;
        }
 
-out:
-       mana_pre_dealloc_rxbufs(mpc);
+       mana_free_qset(scratch, &oldq);
+
+free_scratch:
+       mana_publish_close_if_needed(mpc);
+       mana_qset_scratch_free(scratch);
+clear_flag:
+       mutex_lock(&mpc->vport_mutex);
+       mpc->channel_changing = false;
+       mutex_unlock(&mpc->vport_mutex);
        return err;
 }
 
@@ -3306,7 +3326,8 @@ static struct mana_rxq *mana_create_rxq(struct 
mana_port_context *apc,
        rxq->rxq_idx = rxq_idx;
        rxq->rxobj = INVALID_MANA_HANDLE;
 
-       mana_get_rxbuf_cfg(apc, ndev->mtu, &rxq->datasize, &rxq->alloc_size,
+       mana_get_rxbuf_cfg(apc, apc->configured_mtu, &rxq->datasize,
+                          &rxq->alloc_size,
                           &rxq->headroom, &rxq->frag_count);
        /* Create page pool for RX queue */
        err = mana_create_page_pool(rxq, gc);
@@ -4017,6 +4038,7 @@ static void mana_qset_snapshot(const struct 
mana_port_context *ctx,
        out->rx_queue_size      = ctx->rx_queue_size;
        out->tx_queue_size      = ctx->tx_queue_size;
        out->priv_flags         = ctx->priv_flags;
+       out->mtu                = ctx->configured_mtu;
 }
 
 /* Vport identity and port debugfs outlive queue sets. */
@@ -4033,6 +4055,7 @@ static void mana_qset_install(struct mana_port_context 
*ctx,
        ctx->rx_queue_size      = qset->rx_queue_size;
        ctx->tx_queue_size      = qset->tx_queue_size;
        ctx->priv_flags         = qset->priv_flags;
+       ctx->configured_mtu     = qset->mtu;
 }
 
 /* Scratch starts without SQs/RQs and borrows the port's EQ pool. Never call
@@ -4073,7 +4096,7 @@ void mana_qset_scratch_free(struct mana_port_context 
*scratch)
 int mana_alloc_qset(struct mana_port_context *apc,
                    struct mana_port_context *scratch, unsigned int num_queues,
                    unsigned int rx_queue_size, unsigned int tx_queue_size,
-                   u32 priv_flags, struct mana_qset *out)
+                   u32 priv_flags, int mtu, struct mana_qset *out)
 {
        struct net_device *ndev = scratch->ndev;
        int err;
@@ -4085,6 +4108,8 @@ int mana_alloc_qset(struct mana_port_context *apc,
        scratch->tx_queue_size  = tx_queue_size;
        scratch->priv_flags     = priv_flags;
 
+       scratch->configured_mtu = mtu;
+
        err = mana_init_port_context(scratch);
        if (err)
                goto out_err;
@@ -4337,6 +4362,8 @@ int mana_publish_qset(struct mana_port_context *apc, 
struct mana_qset *newq,
        if (err)
                goto rollback;
 
+       WRITE_ONCE(ndev->mtu, apc->configured_mtu);
+
        /* Publish fields before opening the gate; pair with TX/XDP read
         * barriers. The post-gate full barrier cannot replace this.
         */
@@ -4392,6 +4419,8 @@ int mana_publish_qset(struct mana_port_context *apc, 
struct mana_qset *newq,
        synchronize_net();
        mana_fold_qset_rx_stats(apc, out_old);
 
+       WRITE_ONCE(ndev->mtu, apc->configured_mtu);
+
        /* Publish restored fields before reopening the gate, as on success. */
        smp_wmb();
 
@@ -4544,6 +4573,7 @@ static int mana_probe_port(struct mana_context *ac, int 
port_idx,
        apc->port_handle = INVALID_MANA_HANDLE;
        apc->pf_filter_handle = INVALID_MANA_HANDLE;
        apc->port_idx = port_idx;
+       apc->configured_mtu = ndev->mtu;
        apc->link_cfg_error = 1;
        apc->cqe_coalescing_enable = 0;
        apc->cqe8_coalescing_enable = 0;
diff --git a/drivers/net/ethernet/microsoft/mana/mana_ethtool.c 
b/drivers/net/ethernet/microsoft/mana/mana_ethtool.c
index 7a1120342208..2ad0fb4d5008 100644
--- a/drivers/net/ethernet/microsoft/mana/mana_ethtool.c
+++ b/drivers/net/ethernet/microsoft/mana/mana_ethtool.c
@@ -738,7 +738,8 @@ static int mana_set_channels(struct net_device *ndev,
        }
 
        err = mana_alloc_qset(apc, scratch, new_count, apc->rx_queue_size,
-                             apc->tx_queue_size, apc->priv_flags, &newq);
+                             apc->tx_queue_size, apc->priv_flags,
+                             apc->configured_mtu, &newq);
        if (err)
                goto free_scratch;
 
@@ -827,7 +828,7 @@ static int mana_set_ringparam(struct net_device *ndev,
        }
 
        err = mana_alloc_qset(apc, scratch, apc->num_queues, new_rx, new_tx,
-                             apc->priv_flags, &newq);
+                             apc->priv_flags, apc->configured_mtu, &newq);
        if (err) {
                NL_SET_ERR_MSG_FMT(extack, "failed to change ring params: %d",
                                   err);
@@ -917,8 +918,9 @@ static int mana_set_priv_flags(struct net_device *ndev, u32 
priv_flags)
                goto clear_flag;
        }
 
-       err = mana_alloc_qset(apc, scratch, apc->num_queues, apc->rx_queue_size,
-                             apc->tx_queue_size, priv_flags, &newq);
+       err = mana_alloc_qset(apc, scratch, apc->num_queues,
+                             apc->rx_queue_size, apc->tx_queue_size,
+                             priv_flags, apc->configured_mtu, &newq);
        if (err)
                goto free_scratch;
 
diff --git a/include/net/mana/mana.h b/include/net/mana/mana.h
index c66f9dcab407..3faad257e97e 100644
--- a/include/net/mana/mana.h
+++ b/include/net/mana/mana.h
@@ -626,6 +626,10 @@ struct mana_port_context {
        unsigned int rx_queue_size;
        unsigned int tx_queue_size;
 
+       /* MTU used to size RX buffers, independent of ndev->mtu during a swap.
+        */
+       int configured_mtu;
+
        mana_handle_t port_handle;
        mana_handle_t pf_filter_handle;
 
@@ -702,6 +706,7 @@ struct mana_qset {
        unsigned int            tx_queue_size;
        u32                     priv_flags;
 
+       int                     mtu;
 };
 
 netdev_tx_t mana_start_xmit(struct sk_buff *skb, struct net_device *ndev);
@@ -724,7 +729,7 @@ static inline struct mana_stats_rx *mana_rxq_stats(struct 
mana_rxq *rxq)
 int mana_alloc_qset(struct mana_port_context *apc,
                    struct mana_port_context *scratch, unsigned int num_queues,
                    unsigned int rx_queue_size, unsigned int tx_queue_size,
-                   u32 priv_flags, struct mana_qset *out);
+                   u32 priv_flags, int mtu, struct mana_qset *out);
 int mana_publish_qset(struct mana_port_context *apc, struct mana_qset *newq,
                      struct mana_qset *out_old);
 void mana_publish_close_if_needed(struct mana_port_context *apc);

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