netdev - [PATCH net-next 7/9] i40e: drop useless bitmap_weight() call in i40e_set_rxfh

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Message-ID: <20260206174910.4066255-8-anthony.l.nguyen@intel.com>
Date: Fri,  6 Feb 2026 09:49:04 -0800
From: Tony Nguyen <anthony.l.nguyen@...el.com>
To: davem@...emloft.net,
	kuba@...nel.org,
	pabeni@...hat.com,
	edumazet@...gle.com,
	andrew+netdev@...n.ch,
	netdev@...r.kernel.org
Cc: "Yury Norov (NVIDIA)" <yury.norov@...il.com>,
	anthony.l.nguyen@...el.com,
	Simon Horman <horms@...nel.org>,
	Rinitha S <sx.rinitha@...el.com>
Subject: [PATCH net-next 7/9] i40e: drop useless bitmap_weight() call in i40e_set_rxfh_fields()

From: "Yury Norov (NVIDIA)" <yury.norov@...il.com>

bitmap_weight() is O(N) and useless here, because the following
for_each_set_bit() returns immediately in case of empty flow_pctypes.

Signed-off-by: Yury Norov (NVIDIA) <yury.norov@...il.com>
Reviewed-by: Simon Horman <horms@...nel.org>
Tested-by: Rinitha S <sx.rinitha@...el.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@...el.com>
---
 .../net/ethernet/intel/i40e/i40e_ethtool.c    | 21 +++++++------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_ethtool.c b/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
index 6a47ea0927e9..9fca52f42ce4 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
@@ -3625,6 +3625,7 @@ static int i40e_set_rxfh_fields(struct net_device *netdev,
 		   ((u64)i40e_read_rx_ctl(hw, I40E_PFQF_HENA(1)) << 32);
 	DECLARE_BITMAP(flow_pctypes, FLOW_PCTYPES_SIZE);
 	u64 i_set, i_setc;
+	u8 flow_id;
 
 	bitmap_zero(flow_pctypes, FLOW_PCTYPES_SIZE);
 
@@ -3708,20 +3709,14 @@ static int i40e_set_rxfh_fields(struct net_device *netdev,
 		return -EINVAL;
 	}
 
-	if (bitmap_weight(flow_pctypes, FLOW_PCTYPES_SIZE)) {
-		u8 flow_id;
+	for_each_set_bit(flow_id, flow_pctypes, FLOW_PCTYPES_SIZE) {
+		i_setc = (u64)i40e_read_rx_ctl(hw, I40E_GLQF_HASH_INSET(0, flow_id)) |
+			 ((u64)i40e_read_rx_ctl(hw, I40E_GLQF_HASH_INSET(1, flow_id)) << 32);
+		i_set = i40e_get_rss_hash_bits(&pf->hw, nfc, i_setc);
 
-		for_each_set_bit(flow_id, flow_pctypes, FLOW_PCTYPES_SIZE) {
-			i_setc = (u64)i40e_read_rx_ctl(hw, I40E_GLQF_HASH_INSET(0, flow_id)) |
-				 ((u64)i40e_read_rx_ctl(hw, I40E_GLQF_HASH_INSET(1, flow_id)) << 32);
-			i_set = i40e_get_rss_hash_bits(&pf->hw, nfc, i_setc);
-
-			i40e_write_rx_ctl(hw, I40E_GLQF_HASH_INSET(0, flow_id),
-					  (u32)i_set);
-			i40e_write_rx_ctl(hw, I40E_GLQF_HASH_INSET(1, flow_id),
-					  (u32)(i_set >> 32));
-			hena |= BIT_ULL(flow_id);
-		}
+		i40e_write_rx_ctl(hw, I40E_GLQF_HASH_INSET(0, flow_id), (u32)i_set);
+		i40e_write_rx_ctl(hw, I40E_GLQF_HASH_INSET(1, flow_id), (u32)(i_set >> 32));
+		hena |= BIT_ULL(flow_id);
 	}
 
 	i40e_write_rx_ctl(hw, I40E_PFQF_HENA(0), (u32)hena);
-- 
2.47.1