netdev - [PATCH net-next] r8169: remove multicast filter limit

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Date: Mon, 27 Nov 2023 21:16:10 +0100
From: Heiner Kallweit <hkallweit1@...il.com>
To: Realtek linux nic maintainers <nic_swsd@...ltek.com>,
 Paolo Abeni <pabeni@...hat.com>, Jakub Kicinski <kuba@...nel.org>,
 Eric Dumazet <edumazet@...gle.com>, David Miller <davem@...emloft.net>
Cc: "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: [PATCH net-next] r8169: remove multicast filter limit

Once upon a time, when r8169 was new, the multicast filter limit code
was copied from RTL8139 driver. There the filter limit is even
user-configurable.
The filtering is hash-based and we don't have perfect filtering.
Actually the mc filtering on RTL8125 still seems to be the same
as used on 8390/NE2000. So it's not clear to me which benefit it
should bring when switching to all-multi mode once a certain number
of filter bits is set. More the opposite: Filtering out at least
some unwanted mc traffic is better than no filtering.
Also the available chip documentation doesn't mention any restriction.
Therefore remove the filter limit.

Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
---
 drivers/net/ethernet/realtek/r8169_main.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index dbc5c9d35..0aed99a20 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -56,10 +56,6 @@
 #define FIRMWARE_8125A_3	"rtl_nic/rtl8125a-3.fw"
 #define FIRMWARE_8125B_2	"rtl_nic/rtl8125b-2.fw"
 
-/* Maximum number of multicast addresses to filter (vs. Rx-all-multicast).
-   The RTL chips use a 64 element hash table based on the Ethernet CRC. */
-#define	MC_FILTER_LIMIT	32
-
 #define TX_DMA_BURST	7	/* Maximum PCI burst, '7' is unlimited */
 #define InterFrameGap	0x03	/* 3 means InterFrameGap = the shortest one */
 
@@ -2597,8 +2593,7 @@ static void rtl_set_rx_mode(struct net_device *dev)
 		rx_mode |= AcceptAllPhys;
 	} else if (!(dev->flags & IFF_MULTICAST)) {
 		rx_mode &= ~AcceptMulticast;
-	} else if (netdev_mc_count(dev) > MC_FILTER_LIMIT ||
-		   dev->flags & IFF_ALLMULTI ||
+	} else if (dev->flags & IFF_ALLMULTI ||
 		   tp->mac_version == RTL_GIGA_MAC_VER_35) {
 		/* accept all multicasts */
 	} else if (netdev_mc_empty(dev)) {
-- 
2.43.0