[PATCH net-next v4 08/15] net: dsa: tag_sja1105: absorb logic for not overwriting precise info into dsa_8021q_rcv()

Pawel Dembicki
2024-02-13T22:05:47Z

From: Vladimir Oltean <vladimir.oltean@nxp.com>

In both sja1105_rcv() and sja1110_rcv(), we may have precise source port
information coming from parallel hardware mechanisms, in addition to the
tag_8021q header.

Only sja1105_rcv() has extra logic to not overwrite that precise info
with what's present in the VLAN tag. This is because sja1110_rcv() gets
by, by having a reversed set of checks when assigning skb->dev. When the
source port is imprecise (vbid >=1), source_port and switch_id will be
set to zeroes by dsa_8021q_rcv(), which might be problematic. But by
checking for vbid >= 1 first, sja1110_rcv() fends that off.

We would like to make more code common between sja1105_rcv() and
sja1110_rcv(), and for that, we need to make sure that sja1110_rcv()
also goes through the precise source port preservation logic.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
v4:
- introduced patch

net/dsa/tag_8021q.c | 32 +++++++++++++++++++++++++++++---
net/dsa/tag_sja1105.c | 23 +++--------------------
2 files changed, 32 insertions(+), 23 deletions(-)

diff --git a/net/dsa/tag_8021q.c b/net/dsa/tag_8021q.c
index 71b26ae6db39..3cb0293793a5 100644
--- a/net/dsa/tag_8021q.c
+++ b/net/dsa/tag_8021q.c
@@ -497,9 +497,21 @@ struct net_device *dsa_tag_8021q_find_port_by_vbid(struct net_device *conduit,
}
EXPORT_SYMBOL_GPL(dsa_tag_8021q_find_port_by_vbid);

+/**
+ * dsa_8021q_rcv - Decode source information from tag_8021q header
+ * @skb: RX socket buffer
+ * @source_port: pointer to storage for precise source port information.
+ * If this is known already from outside tag_8021q, the pre-initialized
+ * value is preserved. If not known, pass -1.
+ * @switch_id: similar to source_port.
+ * @vbid: pointer to storage for imprecise bridge ID. Must be pre-initialized
+ * with -1. If a positive value is returned, the source_port and switch_id
+ * are invalid.
+ */
void dsa_8021q_rcv(struct sk_buff *skb, int *source_port, int *switch_id,
int *vbid)
{
+ int tmp_source_port, tmp_switch_id, tmp_vbid;
u16 vid, tci;

if (skb_vlan_tag_present(skb)) {
@@ -513,11 +525,25 @@ void dsa_8021q_rcv(struct sk_buff *skb, int *source_port, int *switch_id,

vid = tci & VLAN_VID_MASK;

- *source_port = dsa_8021q_rx_source_port(vid);
- *switch_id = dsa_8021q_rx_switch_id(vid);
+ tmp_source_port = dsa_8021q_rx_source_port(vid);
+ tmp_switch_id = dsa_8021q_rx_switch_id(vid);
+ tmp_vbid = dsa_tag_8021q_rx_vbid(vid);
+
+ /* Precise source port information is unknown when receiving from a
+ * VLAN-unaware bridging domain, and tmp_source_port and tmp_switch_id
+ * are zeroes in this case.
+ *
+ * Preserve the source information from hardware-specific mechanisms,
+ * if available. This allows us to not overwrite a valid source port
+ * and switch ID with less precise values.
+ */
+ if (tmp_vbid == 0 && *source_port == -1)
+ *source_port = tmp_source_port;
+ if (tmp_vbid == 0 && *switch_id == -1)
+ *switch_id = tmp_switch_id;

if (vbid)
- *vbid = dsa_tag_8021q_rx_vbid(vid);
+ *vbid = tmp_vbid;

skb->priority = (tci & VLAN_PRIO_MASK) >> VLAN_PRIO_SHIFT;
}
diff --git a/net/dsa/tag_sja1105.c b/net/dsa/tag_sja1105.c
index 1aba1d05c27a..48886d4b7e3e 100644
--- a/net/dsa/tag_sja1105.c
+++ b/net/dsa/tag_sja1105.c
@@ -524,30 +524,13 @@ static struct sk_buff *sja1105_rcv(struct sk_buff *skb,
/* Normal data plane traffic and link-local frames are tagged with
* a tag_8021q VLAN which we have to strip
*/
- if (sja1105_skb_has_tag_8021q(skb)) {
- int tmp_source_port = -1, tmp_switch_id = -1;
-
- sja1105_vlan_rcv(skb, &tmp_source_port, &tmp_switch_id, &vbid,
- &vid);
- /* Preserve the source information from the INCL_SRCPT option,
- * if available. This allows us to not overwrite a valid source
- * port and switch ID with zeroes when receiving link-local
- * frames from a VLAN-unaware bridged port (non-zero vbid) or a
- * VLAN-aware bridged port (non-zero vid). Furthermore, the
- * tag_8021q source port information is only of trust when the
- * vbid is 0 (precise port). Otherwise, tmp_source_port and
- * tmp_switch_id will be zeroes.
- */
- if (vbid == 0 && source_port == -1)
- source_port = tmp_source_port;
- if (vbid == 0 && switch_id == -1)
- switch_id = tmp_switch_id;
- } else if (source_port == -1 && switch_id == -1) {
+ if (sja1105_skb_has_tag_8021q(skb))
+ sja1105_vlan_rcv(skb, &source_port, &switch_id, &vbid, &vid);
+ else if (source_port == -1 && switch_id == -1)
/* Packets with no source information have no chance of
* getting accepted, drop them straight away.
*/
return NULL;
- }

if (source_port != -1 && switch_id != -1)
skb->dev = dsa_conduit_find_user(netdev, switch_id, source_port);
--
2.34.1