mlxsw: spectrum_fid: use a dedicated list head pointer for sorted insert

Browse source

mlxsw_sp_fid_port_vid_list_add() inserts into a list sorted by
local_port. It walks the list to find the first entry with a
larger local_port, then inserts the new entry before it:

    list_add_tail(&port_vid->list, &tmp_port_vid->list);

If the loop falls through (the new local_port is the largest),
tmp_port_vid runs off the end of the list. &tmp_port_vid->list
then ends up at the list head itself (container_of() offsets
cancel), and list_add_tail() inserts at the tail. So the code
works today.

It is fragile though. Anyone who later adds a read of another
field of tmp_port_vid will hit memory outside the list head.

Track the insertion point with a dedicated list_head pointer.
Initialise insert_before to &fid->port_vid_list, set it to
&tmp_port_vid->list only on early break, and pass insert_before
to list_add_tail(). The cursor is no longer touched after the
loop. Behaviour is unchanged.

Same shape as the Koschel cleanups from 2022 (e.g. 99d8ae4ec8
tracing, 2966a9918d clockevents, dc1acd5c94 dlm).

Signed-off-by: Maoyi Xie <maoyixie.tju@gmail.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260525071759.1517576-1-maoyixie.tju@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

...

This commit is contained in:

Maoyi Xie 2026-05-25 15:17:59 +08:00 • committed by Jakub Kicinski

parent 10006ad04b

commit 6373d6fbc2

1 changed files with 5 additions and 2 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

7

drivers/net/ethernet/mellanox/mlxsw/spectrum_fid.c

View file