[PATCH net-next v2 07/14] net: macb: avoid macb_init_rx_buffer_size() modifying state

Théo Lebrun
2026-04-10T19:52:25Z

macb_init_rx_buffer_size() takes the macb private data struct and
overrides its bp->ctx->rx_buffer_size. To make it usable with multiple
contexts, make it return its value.

Also, move the `bufsz` computation into it. The value is only used if
GEM, and for historical reason it currently lives in macb_open().

Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
---
drivers/net/ethernet/cadence/macb_main.c | 26 +++++++++++++-------------
1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 3e596cbe9fc8..2eddc7892073 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -2615,25 +2615,26 @@ static netdev_tx_t macb_start_xmit(struct sk_buff *skb,
return ret;
}

-static void macb_init_rx_buffer_size(struct macb *bp, size_t size)
+static unsigned int macb_rx_buffer_size(struct macb *bp, unsigned int mtu)
{
- if (!macb_is_gem(bp)) {
- bp->ctx->rx_buffer_size = MACB_RX_BUFFER_SIZE;
- } else {
- bp->ctx->rx_buffer_size = MIN(size, RX_BUFFER_MAX);
+ unsigned int size;

- if (bp->ctx->rx_buffer_size % RX_BUFFER_MULTIPLE) {
+ if (!macb_is_gem(bp)) {
+ size = MACB_RX_BUFFER_SIZE;
+ } else {
+ size = mtu + ETH_HLEN + ETH_FCS_LEN + NET_IP_ALIGN;
+ size = MIN(size, RX_BUFFER_MAX);
+
+ if (size % RX_BUFFER_MULTIPLE) {
netdev_dbg(bp->netdev,
"RX buffer must be multiple of %d bytes, expanding\n",
RX_BUFFER_MULTIPLE);
- bp->ctx->rx_buffer_size =
- roundup(bp->ctx->rx_buffer_size,
- RX_BUFFER_MULTIPLE);
+ size = roundup(size, RX_BUFFER_MULTIPLE);
}
}

- netdev_dbg(bp->netdev, "mtu [%u] rx_buffer_size [%u]\n",
- bp->netdev->mtu, bp->ctx->rx_buffer_size);
+ netdev_dbg(bp->netdev, "mtu [%u] rx_buffer_size [%u]\n", mtu, size);
+ return size;
}

static void gem_free_rx_buffers(struct macb *bp)
@@ -3177,7 +3178,6 @@ static void macb_set_rx_mode(struct net_device *netdev)

static int macb_open(struct net_device *netdev)
{
- size_t bufsz = netdev->mtu + ETH_HLEN + ETH_FCS_LEN + NET_IP_ALIGN;
struct macb *bp = netdev_priv(netdev);
struct macb_queue *queue;
unsigned int q;
@@ -3196,7 +3196,7 @@ static int macb_open(struct net_device *netdev)
}

/* RX buffers initialization */
- macb_init_rx_buffer_size(bp, bufsz);
+ bp->ctx->rx_buffer_size = macb_rx_buffer_size(bp, netdev->mtu);
bp->ctx->rx_ring_size = bp->configured_rx_ring_size;
bp->ctx->tx_ring_size = bp->configured_tx_ring_size;

--
2.53.0