[PATCH net-next v2 2/3] bnxt_en: Resize RSS contexts on channel count change

["Björn Töpel" <bjorn@kernel.org>]

bnxt_set_channels() rejects channel changes that alter the RSS table
size when IFF_RXFH_CONFIGURED is set, because non-default context
sizes were locked at creation.

Replace the rejection with the new resize helpers. All validation runs
before the device is closed; actual resize is deferred until after
bnxt_close_nic():

 1. ethtool_rxfh_can_resize() checks context 0.
 2. ethtool_rxfh_ctxs_can_resize() validates all non-default contexts.
 3. After bnxt_close_nic(), ethtool_rxfh_resize() applies context 0
    changes, and ethtool_rxfh_ctxs_resize() resizes non-default
    contexts.

RSS table size only changes on P5 chips with older firmware; newer
firmware always uses the largest table size.

When context 0 uses defaults (!IFF_RXFH_CONFIGURED), steps 1 and 3 are
skipped; the driver regenerates the table via
bnxt_set_dflt_rss_indir_tbl().

Signed-off-by: Björn Töpel <bjorn@kernel.org>
---
 .../net/ethernet/broadcom/bnxt/bnxt_ethtool.c | 36 +++++++++++++++----
 1 file changed, 29 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
index 26fcd52c8a61..1bb0dd5bb683 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
@@ -942,6 +942,7 @@ static int bnxt_set_channels(struct net_device *dev,
 {
 	struct bnxt *bp = netdev_priv(dev);
 	int req_tx_rings, req_rx_rings, tcs;
+	u32 new_tbl_size = 0, old_tbl_size;
 	bool sh = false;
 	int tx_xdp = 0;
 	int rc = 0;
@@ -977,19 +978,33 @@ static int bnxt_set_channels(struct net_device *dev,
 		tx_xdp = req_rx_rings;
 	}
 
-	if (bnxt_get_nr_rss_ctxs(bp, req_rx_rings) !=
-	    bnxt_get_nr_rss_ctxs(bp, bp->rx_nr_rings) &&
-	    netif_is_rxfh_configured(dev)) {
-		netdev_warn(dev, "RSS table size change required, RSS table entries must be default to proceed\n");
-		return -EINVAL;
-	}
-
 	rc = bnxt_check_rings(bp, req_tx_rings, req_rx_rings, sh, tcs, tx_xdp);
 	if (rc) {
 		netdev_warn(dev, "Unable to allocate the requested rings\n");
 		return rc;
 	}
 
+	/* RSS table size only changes on P5 chips with older firmware;
+	 * newer firmware always uses the largest table size.
+	 */
+	if (bnxt_get_nr_rss_ctxs(bp, req_rx_rings) !=
+	    bnxt_get_nr_rss_ctxs(bp, bp->rx_nr_rings)) {
+		new_tbl_size = bnxt_get_nr_rss_ctxs(bp, req_rx_rings) *
+			       BNXT_RSS_TABLE_ENTRIES_P5;
+		old_tbl_size = bnxt_get_rxfh_indir_size(dev);
+
+		if (netif_is_rxfh_configured(dev) &&
+		    ethtool_rxfh_can_resize(bp->rss_indir_tbl,
+					    old_tbl_size, new_tbl_size)) {
+			netdev_warn(dev, "RSS table resize not possible\n");
+			return -EINVAL;
+		}
+
+		rc = ethtool_rxfh_ctxs_can_resize(dev, new_tbl_size);
+		if (rc)
+			return rc;
+	}
+
 	if (netif_running(dev)) {
 		if (BNXT_PF(bp)) {
 			/* TODO CHIMP_FW: Send message to all VF's
@@ -999,6 +1014,13 @@ static int bnxt_set_channels(struct net_device *dev,
 		bnxt_close_nic(bp, true, false);
 	}
 
+	if (new_tbl_size) {
+		if (netif_is_rxfh_configured(dev))
+			ethtool_rxfh_resize(bp->rss_indir_tbl,
+					    old_tbl_size, new_tbl_size);
+		ethtool_rxfh_ctxs_resize(dev, new_tbl_size);
+	}
+
 	if (sh) {
 		bp->flags |= BNXT_FLAG_SHARED_RINGS;
 		bp->rx_nr_rings = channel->combined_count;
-- 
2.53.0