| Message ID | 20211003222312.284175-3-vladimir.oltean@nxp.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | DSA bridge TX forwarding offload fixes - part 1 | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Clearly marked for net |
| netdev/subject_prefix | success | Link |
| netdev/cc_maintainers | fail | 1 blamed authors not CCed: olteanv@gmail.com; 1 maintainers not CCed: olteanv@gmail.com |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 0 this patch: 0 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 8 lines checked |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 0 this patch: 0 |
| netdev/header_inline | success | Link |
diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c index b29262eee00b..6d5cc0217133 100644 --- a/net/dsa/dsa2.c +++ b/net/dsa/dsa2.c @@ -170,7 +170,7 @@ void dsa_bridge_num_put(const struct net_device *bridge_dev, int bridge_num) /* Check if the bridge is still in use, otherwise it is time * to clean it up so we can reuse this bridge_num later. */ - if (!dsa_bridge_num_find(bridge_dev)) + if (dsa_bridge_num_find(bridge_dev) < 0) clear_bit(bridge_num, &dsa_fwd_offloading_bridges); }
The dp->bridge_num is zero-based, with -1 being the encoding for an invalid value. But dsa_bridge_num_put used to check for an invalid value by comparing bridge_num with 0, which is of course incorrect. The result is that the bridge_num will never get cleared by dsa_bridge_num_put, and further port joins to other bridges will get a bridge_num larger than the previous one, and once all the available bridges with TX forwarding offload supported by the hardware get exhausted, the TX forwarding offload feature is simply disabled. In the case of sja1105, 7 iterations of the loop below are enough to exhaust the TX forwarding offload bits, and further bridge joins operate without that feature. ip link add br0 type bridge vlan_filtering 1 while :; do ip link set sw0p2 master br0 && sleep 1 ip link set sw0p2 nomaster && sleep 1 done This issue is enough of an indication that having the dp->bridge_num invalid encoding be a negative number is prone to bugs, so this will be changed to a one-based value, with the dp->bridge_num of zero being the indication of no bridge. However, that is material for net-next. Fixes: f5e165e72b29 ("net: dsa: track unique bridge numbers across all DSA switch trees") Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> --- net/dsa/dsa2.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)