bnxt_en: Fix max_mtu setting for multi-buf XDP

[ Upstream commit 08450ea ]

The existing code does not allow the MTU to be set to the maximum even
after an XDP program supporting multiple buffers is attached.  Fix it
to set the netdev->max_mtu to the maximum value if the attached XDP
program supports mutiple buffers, regardless of the current MTU value.

Also use a local variable dev instead of repeatedly using bp->dev.

Fixes: 1dc4c55 ("bnxt: adding bnxt_xdp_build_skb to build skb from multibuffer xdp_buff")
Reviewed-by: Somnath Kotur <somnath.kotur@broadcom.com>
Reviewed-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
Reviewed-by: Andy Gospodarek <andrew.gospodarek@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Link: https://lore.kernel.org/r/20230731142043.58855-3-michael.chan@broadcom.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -4027,26 +4027,29 @@ void bnxt_set_ring_params(struct bnxt *bp)
  */
 int bnxt_set_rx_skb_mode(struct bnxt *bp, bool page_mode)
 {
+	struct net_device *dev = bp->dev;
+
 	if (page_mode) {
 		bp->flags &= ~BNXT_FLAG_AGG_RINGS;
 		bp->flags |= BNXT_FLAG_RX_PAGE_MODE;
 
-		if (bp->dev->mtu > BNXT_MAX_PAGE_MODE_MTU) {
+		if (bp->xdp_prog->aux->xdp_has_frags)
+			dev->max_mtu = min_t(u16, bp->max_mtu, BNXT_MAX_MTU);
+		else
+			dev->max_mtu =
+				min_t(u16, bp->max_mtu, BNXT_MAX_PAGE_MODE_MTU);
+		if (dev->mtu > BNXT_MAX_PAGE_MODE_MTU) {
 			bp->flags |= BNXT_FLAG_JUMBO;
 			bp->rx_skb_func = bnxt_rx_multi_page_skb;
-			bp->dev->max_mtu =
-				min_t(u16, bp->max_mtu, BNXT_MAX_MTU);
 		} else {
 			bp->flags |= BNXT_FLAG_NO_AGG_RINGS;
 			bp->rx_skb_func = bnxt_rx_page_skb;
-			bp->dev->max_mtu =
-				min_t(u16, bp->max_mtu, BNXT_MAX_PAGE_MODE_MTU);
 		}
 		bp->rx_dir = DMA_BIDIRECTIONAL;
 		/* Disable LRO or GRO_HW */
-		netdev_update_features(bp->dev);
+		netdev_update_features(dev);
 	} else {
-		bp->dev->max_mtu = bp->max_mtu;
+		dev->max_mtu = bp->max_mtu;
 		bp->flags &= ~BNXT_FLAG_RX_PAGE_MODE;
 		bp->rx_dir = DMA_FROM_DEVICE;
 		bp->rx_skb_func = bnxt_rx_skb;