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net: dsa: tag_sja1105: absorb logic for not overwriting precise info into dsa_8021q_rcv()

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>
Signed-off-by: Pawel Dembicki <paweldembicki@gmail.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Tested-by: Vladimir Oltean <olteanv@gmail.com>
Link: https://patch.msgid.link/20240713211620.1125910-4-paweldembicki@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

authored by

Vladimir Oltean and committed by
Jakub Kicinski dcfe7673 6b783ded

+32 -23
+29 -3
net/dsa/tag_8021q.c
··· 497 497 } 498 498 EXPORT_SYMBOL_GPL(dsa_tag_8021q_find_port_by_vbid); 499 499 500 + /** 501 + * dsa_8021q_rcv - Decode source information from tag_8021q header 502 + * @skb: RX socket buffer 503 + * @source_port: pointer to storage for precise source port information. 504 + * If this is known already from outside tag_8021q, the pre-initialized 505 + * value is preserved. If not known, pass -1. 506 + * @switch_id: similar to source_port. 507 + * @vbid: pointer to storage for imprecise bridge ID. Must be pre-initialized 508 + * with -1. If a positive value is returned, the source_port and switch_id 509 + * are invalid. 510 + */ 500 511 void dsa_8021q_rcv(struct sk_buff *skb, int *source_port, int *switch_id, 501 512 int *vbid) 502 513 { 514 + int tmp_source_port, tmp_switch_id, tmp_vbid; 503 515 u16 vid, tci; 504 516 505 517 if (skb_vlan_tag_present(skb)) { ··· 525 513 526 514 vid = tci & VLAN_VID_MASK; 527 515 528 - *source_port = dsa_8021q_rx_source_port(vid); 529 - *switch_id = dsa_8021q_rx_switch_id(vid); 516 + tmp_source_port = dsa_8021q_rx_source_port(vid); 517 + tmp_switch_id = dsa_8021q_rx_switch_id(vid); 518 + tmp_vbid = dsa_tag_8021q_rx_vbid(vid); 519 + 520 + /* Precise source port information is unknown when receiving from a 521 + * VLAN-unaware bridging domain, and tmp_source_port and tmp_switch_id 522 + * are zeroes in this case. 523 + * 524 + * Preserve the source information from hardware-specific mechanisms, 525 + * if available. This allows us to not overwrite a valid source port 526 + * and switch ID with less precise values. 527 + */ 528 + if (tmp_vbid == 0 && *source_port == -1) 529 + *source_port = tmp_source_port; 530 + if (tmp_vbid == 0 && *switch_id == -1) 531 + *switch_id = tmp_switch_id; 530 532 531 533 if (vbid) 532 - *vbid = dsa_tag_8021q_rx_vbid(vid); 534 + *vbid = tmp_vbid; 533 535 534 536 skb->priority = (tci & VLAN_PRIO_MASK) >> VLAN_PRIO_SHIFT; 535 537 }
+3 -20
net/dsa/tag_sja1105.c
··· 524 524 /* Normal data plane traffic and link-local frames are tagged with 525 525 * a tag_8021q VLAN which we have to strip 526 526 */ 527 - if (sja1105_skb_has_tag_8021q(skb)) { 528 - int tmp_source_port = -1, tmp_switch_id = -1; 529 - 530 - sja1105_vlan_rcv(skb, &tmp_source_port, &tmp_switch_id, &vbid, 531 - &vid); 532 - /* Preserve the source information from the INCL_SRCPT option, 533 - * if available. This allows us to not overwrite a valid source 534 - * port and switch ID with zeroes when receiving link-local 535 - * frames from a VLAN-unaware bridged port (non-zero vbid) or a 536 - * VLAN-aware bridged port (non-zero vid). Furthermore, the 537 - * tag_8021q source port information is only of trust when the 538 - * vbid is 0 (precise port). Otherwise, tmp_source_port and 539 - * tmp_switch_id will be zeroes. 540 - */ 541 - if (vbid == 0 && source_port == -1) 542 - source_port = tmp_source_port; 543 - if (vbid == 0 && switch_id == -1) 544 - switch_id = tmp_switch_id; 545 - } else if (source_port == -1 && switch_id == -1) { 527 + if (sja1105_skb_has_tag_8021q(skb)) 528 + sja1105_vlan_rcv(skb, &source_port, &switch_id, &vbid, &vid); 529 + else if (source_port == -1 && switch_id == -1) 546 530 /* Packets with no source information have no chance of 547 531 * getting accepted, drop them straight away. 548 532 */ 549 533 return NULL; 550 - } 551 534 552 535 if (source_port != -1 && switch_id != -1) 553 536 skb->dev = dsa_conduit_find_user(netdev, switch_id, source_port);