Difuse/difos
2
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

realtek: rtl838x: fix broadcast flooding with many multicast entries

Browse source 
When many multicast entries are installed broadcast flooding might
potentially stop working for several ports. This is because the layer
2 broadcast flood port mask index has the wrong offset. It should be
9 bits, matching the 2^9 = 512 indexes on rtl838x, not 12.

The wrong offset leads to L2_BC_FLD_PMSK being set to 504, not 511
((511 << 12) >> 9) & 511 = 504). So, as by default an unset PMSK
is set to all ports, the issue would only become noticeable once
many multicast entries are installed, causing the 504th entry to be set
to something other than all ports.

Fixing this by setting the offset to 9 bits, to correctly point to our
511th reserved entry for all ports.

Tested-on: ZyXEL GS1900-24HP v1

Fixes: 28e972b2ea ("realtek: Configure initial L2 learning setup")
Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
Link: https://github.com/openwrt/openwrt/pull/18733
Signed-off-by: Robert Marko <robimarko@gmail.com>
This commit is contained in:
Linus Lüssing 2025-05-07 02:50:11 +02:00 committed by Robert Marko
parent 0b4ddeed5e
commit 1b7fd8464c
1 changed files with 1 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
target/linux/realtek/files-6.6/drivers/net/dsa/rtl83xx/rtl838x.c
View file

@ -502,7 +502,7 @@ static void rtl838x_l2_learning_setup(void)
/* Set portmask for broadcast traffic and unknown unicast address flooding /* Set portmask for broadcast traffic and unknown unicast address flooding
* to the reserved entry in the portmask table used also for * to the reserved entry in the portmask table used also for
* multicast flooding */ * multicast flooding */
sw_w32(UNKNOWN_MC_PMASK << 12 | UNKNOWN_MC_PMASK, RTL838X_L2_FLD_PMSK); sw_w32(UNKNOWN_MC_PMASK << 9 | UNKNOWN_MC_PMASK, RTL838X_L2_FLD_PMSK);
/* Enable learning constraint system-wide (bit 0), per-port (bit 1) /* Enable learning constraint system-wide (bit 0), per-port (bit 1)
* and per vlan (bit 2) */ * and per vlan (bit 2) */