diff mbox series

[RFC,net-next,5/6] net: dsa: allow matchall mirroring rules towards the CPU

Message ID 20240913152915.2981126-6-vladimir.oltean@nxp.com (mailing list archive)
State RFC
Delegated to: Netdev Maintainers
Headers show
Series Mirroring to DSA CPU port | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 16 this patch: 16
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 7 of 7 maintainers
netdev/build_clang success Errors and warnings before: 16 this patch: 16
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 16 this patch: 16
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 49 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Vladimir Oltean Sept. 13, 2024, 3:29 p.m. UTC
If the CPU bandwidth capacity permits, it may be useful to mirror the
entire ingress of a user port to software.

This is in fact possible to express even if there is no net_device
representation for the CPU port. In fact, that representation wouldn't
have even helped.

The idea behind implementing this is that currently, we refuse to
offload any mirroring towards a non-DSA target net_device. But if we
acknowledge the fact that to reach any foreign net_device, the switch
must send the packet to the CPU anyway, then we can simply offload just
that part, and let the software do the rest.

Example:

$ ip link add dummy0 type dummy; ip link set dummy0 up
$ tc qdisc add dev swp0 clsact
$ tc filter add dev swp0 ingress matchall action mirred ingress mirror dev dummy0

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
 net/dsa/user.c | 31 +++++++++++++++++++++++++------
 1 file changed, 25 insertions(+), 6 deletions(-)
diff mbox series

Patch

diff --git a/net/dsa/user.c b/net/dsa/user.c
index c8ddbe22d647..bd3e3944931e 100644
--- a/net/dsa/user.c
+++ b/net/dsa/user.c
@@ -1365,7 +1365,7 @@  dsa_user_mall_tc_entry_find(struct net_device *dev, unsigned long cookie)
 static int
 dsa_user_add_cls_matchall_mirred(struct net_device *dev,
 				 struct tc_cls_matchall_offload *cls,
-				 bool ingress)
+				 bool ingress, bool ingress_target)
 {
 	struct netlink_ext_ack *extack = cls->common.extack;
 	struct dsa_port *dp = dsa_user_to_port(dev);
@@ -1398,10 +1398,25 @@  dsa_user_add_cls_matchall_mirred(struct net_device *dev,
 	if (!act->dev)
 		return -EINVAL;
 
-	if (!dsa_user_dev_check(act->dev))
-		return -EOPNOTSUPP;
-
-	to_dp = dsa_user_to_port(act->dev);
+	if (dsa_user_dev_check(act->dev)) {
+		if (ingress_target) {
+			NL_SET_ERR_MSG_MOD(extack,
+					   "Cannot mirror to ingress of target port");
+			return -EOPNOTSUPP;
+		}
+		to_dp = dsa_user_to_port(act->dev);
+	} else {
+		/* Handle mirroring to foreign target ports as a mirror towards
+		 * the CPU. The software tc rule will take the packets from
+		 * there.
+		 */
+		if (cls->skip_sw) {
+			NL_SET_ERR_MSG_MOD(extack,
+					   "Can only mirred to CPU if filter also runs in software");
+			return -EOPNOTSUPP;
+		}
+		to_dp = dp->cpu_dp;
+	}
 
 	if (dp->ds != to_dp->ds) {
 		NL_SET_ERR_MSG_MOD(extack,
@@ -1506,7 +1521,11 @@  static int dsa_user_add_cls_matchall(struct net_device *dev,
 
 	switch (action->entries[0].id) {
 	case FLOW_ACTION_MIRRED:
-		return dsa_user_add_cls_matchall_mirred(dev, cls, ingress);
+		return dsa_user_add_cls_matchall_mirred(dev, cls, ingress,
+							false);
+	case FLOW_ACTION_MIRRED_INGRESS:
+		return dsa_user_add_cls_matchall_mirred(dev, cls, ingress,
+							true);
 	case FLOW_ACTION_POLICE:
 		return dsa_user_add_cls_matchall_police(dev, cls, ingress);
 	default: