Support setting the FDB limit through ip link. The arguments is: - fdb_max_learned: A 32-bit unsigned integer specifying the maximum number of learned FDB entries, with 0 disabling the limit.

Also support reading back the current number of learned FDB entries in the bridge by this count. The returned value's name is: - fdb_n_learned: A 32-bit unsigned integer specifying the current number of learned FDB entries.

Example:

# ip -d -j -p link show br0 [ { ... "linkinfo": { "info_kind": "bridge", "info_data": { ... "fdb_n_learned": 2, "fdb_max_learned": 0, ... } }, ... } ] # ip link set br0 type bridge fdb_max_learned 1024 # ip -d -j -p link show br0 [ { ... "linkinfo": { "info_kind": "bridge", "info_data": { ... "fdb_n_learned": 2, "fdb_max_learned": 1024, ... } }, ... } ]

Signed-off-by: Johannes Nixdorf jnixdorf-oss@avm.de --- I will resend this mail as non-rfc after the kernel UAPI changes landed.

Link to the kernel changes: https://lore.kernel.org/netdev/20230919-fdb_limit-v4-0-39f0293807b8@avm.de/ --- Changes in v4: - Removed _entries from the names. (from review) - Removed the UAPI change, to be synced from linux separately by the maintainer. (from review) For local testing e.g. `make CCOPTS="-O2 -pipe -I${path_to_dev_kernel_headers}"` works as a workaround. - Downgraded to an RFC until the kernel changes land. - Link to v3: https://lore.kernel.org/netdev/20230905-fdb_limit-v3-1-34bb124556d8@avm.de/

Changes in v3: - Properly split the net-next and iproute2-next threads. (from review) - Changed to *_n_* instead of *_cur_*. (from review) - Use strcmp() instead of matches(). (from review) - Made names in code and documentation consistent. (from review) - Various documentation fixes. (from review) - Link to v2: https://lore.kernel.org/netdev/20230619071444.14625-1-jnixdorf-oss@avm.de/

Changes in v2: - Sent out the first corresponding iproute2 patches. - Link to v1: https://lore.kernel.org/netdev/20230515085046.4457-1-jnixdorf-oss@avm.de/ --- ip/iplink_bridge.c | 21 +++++++++++++++++++++ man/man8/ip-link.8.in | 10 ++++++++++ 2 files changed, 31 insertions(+)

diff --git a/ip/iplink_bridge.c b/ip/iplink_bridge.c index 462075295308..6b70ffbb6f5f 100644 --- a/ip/iplink_bridge.c +++ b/ip/iplink_bridge.c @@ -34,6 +34,7 @@ static void print_explain(FILE *f) " [ group_fwd_mask MASK ]\n" " [ group_address ADDRESS ]\n" " [ no_linklocal_learn NO_LINKLOCAL_LEARN ]\n" + " [ fdb_max_learned FDB_MAX_LEARNED ]\n" " [ vlan_filtering VLAN_FILTERING ]\n" " [ vlan_protocol VLAN_PROTOCOL ]\n" " [ vlan_default_pvid VLAN_DEFAULT_PVID ]\n" @@ -168,6 +169,14 @@ static int bridge_parse_opt(struct link_util *lu, int argc, char **argv, bm.optval |= no_ll_learn_bit; else bm.optval &= ~no_ll_learn_bit; + } else if (strcmp(*argv, "fdb_max_learned") == 0) { + __u32 fdb_max_learned; + + NEXT_ARG(); + if (get_u32(&fdb_max_learned, *argv, 0)) + invarg("invalid fdb_max_learned", *argv); + + addattr32(n, 1024, IFLA_BR_FDB_MAX_LEARNED, fdb_max_learned); } else if (matches(*argv, "fdb_flush") == 0) { addattr(n, 1024, IFLA_BR_FDB_FLUSH); } else if (matches(*argv, "vlan_default_pvid") == 0) { @@ -544,6 +553,18 @@ static void bridge_print_opt(struct link_util *lu, FILE *f, struct rtattr *tb[]) if (tb[IFLA_BR_GC_TIMER]) _bridge_print_timer(f, "gc_timer", tb[IFLA_BR_GC_TIMER]);

+ if (tb[IFLA_BR_FDB_N_LEARNED]) + print_uint(PRINT_ANY, + "fdb_n_learned", + "fdb_n_learned %u ", + rta_getattr_u32(tb[IFLA_BR_FDB_N_LEARNED])); + + if (tb[IFLA_BR_FDB_MAX_LEARNED]) + print_uint(PRINT_ANY, + "fdb_max_learned", + "fdb_max_learned %u ", + rta_getattr_u32(tb[IFLA_BR_FDB_MAX_LEARNED])); + if (tb[IFLA_BR_VLAN_DEFAULT_PVID]) print_uint(PRINT_ANY, "vlan_default_pvid", diff --git a/man/man8/ip-link.8.in b/man/man8/ip-link.8.in index 7365d0c6b14f..e82b2dbb0070 100644 --- a/man/man8/ip-link.8.in +++ b/man/man8/ip-link.8.in @@ -1630,6 +1630,8 @@ the following additional arguments are supported: ] [ .BI no_linklocal_learn " NO_LINKLOCAL_LEARN " ] [ +.BI fdb_max_learned " FDB_MAX_LEARNED " +] [ .BI vlan_filtering " VLAN_FILTERING " ] [ .BI vlan_protocol " VLAN_PROTOCOL " @@ -1741,6 +1743,14 @@ or off When disabled, the bridge will not learn from link-local frames (default: enabled).

+.BI fdb_max_learned " FDB_MAX_LEARNED " +- set the maximum number of learned FDB entries. If +.RI ( FDB_MAX_LEARNED " == 0) " +the feature is disabled. Default is +.BR 0 . +.I FDB_MAX_LEARNED +is a 32bit unsigned integer. + .BI vlan_filtering " VLAN_FILTERING " - turn VLAN filtering on .RI ( VLAN_FILTERING " > 0) "

--- base-commit: c31fd80a2268c0b1b77e1d65827003a2327315b8 change-id: 20230905-fdb_limit-ace1467c6a84

Best regards,