[PATCH net-next v3 1/2] net: hsr: Fix PRP duplicate detection

[PATCH net-next v3 1/2] net: hsr: Fix PRP duplicate detection

[Jaakko Karrenpalo]

Add PRP specific function for handling duplicate
packets. This is needed because of potential
L2 802.1p prioritization done by network switches.

The L2 prioritization can re-order the PRP packets
from a node causing the existing implementation to
discard the frame(s) that have been received 'late'
because the sequence number is before the previous
received packet. This can happen if the node is
sending multiple frames back-to-back with different
priority.

Signed-off-by: Jaakko Karrenpalo <jkarrenpalo@gmail.com>
---
Changes in v3:
- Fixed indentation
- Renamed local variables

 net/hsr/hsr_device.c   |  2 +
 net/hsr/hsr_forward.c  |  4 +-
 net/hsr/hsr_framereg.c | 95 ++++++++++++++++++++++++++++++++++++++++--
 net/hsr/hsr_framereg.h |  8 +++-
 net/hsr/hsr_main.h     |  2 +
 5 files changed, 104 insertions(+), 7 deletions(-)

diff --git a/net/hsr/hsr_device.c b/net/hsr/hsr_device.c
index b6fb18469439..2c43776b7c4f 100644
--- a/net/hsr/hsr_device.c
+++ b/net/hsr/hsr_device.c
@@ -616,6 +616,7 @@ static struct hsr_proto_ops hsr_ops = {
 	.drop_frame = hsr_drop_frame,
 	.fill_frame_info = hsr_fill_frame_info,
 	.invalid_dan_ingress_frame = hsr_invalid_dan_ingress_frame,
+	.register_frame_out = hsr_register_frame_out,
 };
 
 static struct hsr_proto_ops prp_ops = {
@@ -626,6 +627,7 @@ static struct hsr_proto_ops prp_ops = {
 	.fill_frame_info = prp_fill_frame_info,
 	.handle_san_frame = prp_handle_san_frame,
 	.update_san_info = prp_update_san_info,
+	.register_frame_out = prp_register_frame_out,
 };
 
 void hsr_dev_setup(struct net_device *dev)
diff --git a/net/hsr/hsr_forward.c b/net/hsr/hsr_forward.c
index a4bacf198555..c67c0d35921d 100644
--- a/net/hsr/hsr_forward.c
+++ b/net/hsr/hsr_forward.c
@@ -536,8 +536,8 @@ static void hsr_forward_do(struct hsr_frame_info *frame)
 		 * Also for SAN, this shouldn't be done.
 		 */
 		if (!frame->is_from_san &&
-		    hsr_register_frame_out(port, frame->node_src,
-					   frame->sequence_nr))
+		    hsr->proto_ops->register_frame_out &&
+		    hsr->proto_ops->register_frame_out(port, frame))
 			continue;
 
 		if (frame->is_supervision && port->type == HSR_PT_MASTER &&
diff --git a/net/hsr/hsr_framereg.c b/net/hsr/hsr_framereg.c
index 73bc6f659812..79e066422044 100644
--- a/net/hsr/hsr_framereg.c
+++ b/net/hsr/hsr_framereg.c
@@ -35,6 +35,7 @@ static bool seq_nr_after(u16 a, u16 b)
 
 #define seq_nr_before(a, b)		seq_nr_after((b), (a))
 #define seq_nr_before_or_eq(a, b)	(!seq_nr_after((a), (b)))
+#define PRP_DROP_WINDOW_LEN 32768
 
 bool hsr_addr_is_redbox(struct hsr_priv *hsr, unsigned char *addr)
 {
@@ -176,8 +177,11 @@ static struct hsr_node *hsr_add_node(struct hsr_priv *hsr,
 		new_node->time_in[i] = now;
 		new_node->time_out[i] = now;
 	}
-	for (i = 0; i < HSR_PT_PORTS; i++)
+	for (i = 0; i < HSR_PT_PORTS; i++) {
 		new_node->seq_out[i] = seq_out;
+		new_node->seq_expected[i] = seq_out + 1;
+		new_node->seq_start[i] = seq_out + 1;
+	}
 
 	if (san && hsr->proto_ops->handle_san_frame)
 		hsr->proto_ops->handle_san_frame(san, rx_port, new_node);
@@ -482,9 +486,11 @@ void hsr_register_frame_in(struct hsr_node *node, struct hsr_port *port,
  *	 0 otherwise, or
  *	 negative error code on error
  */
-int hsr_register_frame_out(struct hsr_port *port, struct hsr_node *node,
-			   u16 sequence_nr)
+int hsr_register_frame_out(struct hsr_port *port, struct hsr_frame_info *frame)
 {
+	struct hsr_node *node = frame->node_src;
+	u16 sequence_nr = frame->sequence_nr;
+
 	spin_lock_bh(&node->seq_out_lock);
 	if (seq_nr_before_or_eq(sequence_nr, node->seq_out[port->type]) &&
 	    time_is_after_jiffies(node->time_out[port->type] +
@@ -499,6 +505,89 @@ int hsr_register_frame_out(struct hsr_port *port, struct hsr_node *node,
 	return 0;
 }
 
+/* Adaptation of the PRP duplicate discard algorithm described in wireshark
+ * wiki (https://wiki.wireshark.org/PRP)
+ *
+ * A drop window is maintained for both LANs with start sequence set to the
+ * first sequence accepted on the LAN that has not been seen on the other LAN,
+ * and expected sequence set to the latest received sequence number plus one.
+ *
+ * When a frame is received on either LAN it is compared against the received
+ * frames on the other LAN. If it is outside the drop window of the other LAN
+ * the frame is accepted and the drop window is updated.
+ * The drop window for the other LAN is reset.
+ *
+ * 'port' is the outgoing interface
+ * 'frame' is the frame to be sent
+ *
+ * Return:
+ *	 1 if frame can be shown to have been sent recently on this interface,
+ *	 0 otherwise
+ */
+int prp_register_frame_out(struct hsr_port *port, struct hsr_frame_info *frame)
+{
+	enum hsr_port_type other_port;
+	enum hsr_port_type rcv_port;
+	struct hsr_node *node;
+	u16 sequence_diff;
+	u16 sequence_exp;
+	u16 sequence_nr;
+
+	/* out-going frames are always in order
+	 *and can be checked the same way as for HSR
+	 */
+	if (frame->port_rcv->type == HSR_PT_MASTER)
+		return hsr_register_frame_out(port, frame);
+
+	/* for PRP we should only forward frames from the slave ports
+	 * to the master port
+	 */
+	if (port->type != HSR_PT_MASTER)
+		return 1;
+
+	node = frame->node_src;
+	sequence_nr = frame->sequence_nr;
+	sequence_exp = sequence_nr + 1;
+	rcv_port = frame->port_rcv->type;
+	other_port =
+		rcv_port == HSR_PT_SLAVE_A ? HSR_PT_SLAVE_B : HSR_PT_SLAVE_A;
+
+	spin_lock_bh(&node->seq_out_lock);
+	if (time_is_before_jiffies(node->time_out[port->type] +
+	    msecs_to_jiffies(HSR_ENTRY_FORGET_TIME)) ||
+	    (node->seq_start[rcv_port] == node->seq_expected[rcv_port] &&
+	    node->seq_start[other_port] == node->seq_expected[other_port])) {
+		/* the node hasn't been sending for a while
+		 * or both drop windows are empty, forward the frame
+		 */
+		node->seq_start[rcv_port] = sequence_nr;
+	} else if (seq_nr_before(sequence_nr, node->seq_expected[other_port]) &&
+		   seq_nr_before_or_eq(node->seq_start[other_port], sequence_nr)) {
+		/* drop the frame, update the drop window for the other port
+		 * and reset our drop window
+		 */
+		node->seq_start[other_port] = sequence_exp;
+		node->seq_expected[rcv_port] = sequence_exp;
+		node->seq_start[rcv_port] = node->seq_expected[rcv_port];
+		spin_unlock_bh(&node->seq_out_lock);
+		return 1;
+	}
+
+	/* update the drop window for the port where this frame was received
+	 * and clear the drop window for the other port
+	 */
+	node->seq_start[other_port] = node->seq_expected[other_port];
+	node->seq_expected[rcv_port] = sequence_exp;
+	sequence_diff = sequence_exp - node->seq_start[rcv_port];
+	if (sequence_diff > PRP_DROP_WINDOW_LEN)
+		node->seq_start[rcv_port] = sequence_exp - PRP_DROP_WINDOW_LEN;
+
+	node->time_out[port->type] = jiffies;
+	node->seq_out[port->type] = sequence_nr;
+	spin_unlock_bh(&node->seq_out_lock);
+	return 0;
+}
+
 static struct hsr_port *get_late_port(struct hsr_priv *hsr,
 				      struct hsr_node *node)
 {
diff --git a/net/hsr/hsr_framereg.h b/net/hsr/hsr_framereg.h
index 993fa950d814..b04948659d84 100644
--- a/net/hsr/hsr_framereg.h
+++ b/net/hsr/hsr_framereg.h
@@ -44,8 +44,7 @@ void hsr_addr_subst_dest(struct hsr_node *node_src, struct sk_buff *skb,
 
 void hsr_register_frame_in(struct hsr_node *node, struct hsr_port *port,
 			   u16 sequence_nr);
-int hsr_register_frame_out(struct hsr_port *port, struct hsr_node *node,
-			   u16 sequence_nr);
+int hsr_register_frame_out(struct hsr_port *port, struct hsr_frame_info *frame);
 
 void hsr_prune_nodes(struct timer_list *t);
 void hsr_prune_proxy_nodes(struct timer_list *t);
@@ -73,6 +72,8 @@ void prp_update_san_info(struct hsr_node *node, bool is_sup);
 bool hsr_is_node_in_db(struct list_head *node_db,
 		       const unsigned char addr[ETH_ALEN]);
 
+int prp_register_frame_out(struct hsr_port *port, struct hsr_frame_info *frame);
+
 struct hsr_node {
 	struct list_head	mac_list;
 	/* Protect R/W access to seq_out */
@@ -89,6 +90,9 @@ struct hsr_node {
 	bool			san_b;
 	u16			seq_out[HSR_PT_PORTS];
 	bool			removed;
+	/* PRP specific duplicate handling */
+	u16			seq_expected[HSR_PT_PORTS];
+	u16			seq_start[HSR_PT_PORTS];
 	struct rcu_head		rcu_head;
 };
 
diff --git a/net/hsr/hsr_main.h b/net/hsr/hsr_main.h
index 7561845b8bf6..1bc47b17a296 100644
--- a/net/hsr/hsr_main.h
+++ b/net/hsr/hsr_main.h
@@ -175,6 +175,8 @@ struct hsr_proto_ops {
 			       struct hsr_frame_info *frame);
 	bool (*invalid_dan_ingress_frame)(__be16 protocol);
 	void (*update_san_info)(struct hsr_node *node, bool is_sup);
+	int (*register_frame_out)(struct hsr_port *port,
+				  struct hsr_frame_info *frame);
 };
 
 struct hsr_self_node {
-- 
2.43.0

[PATCH net-next v3 2/2] net: hsr: Add KUnit test for PRP

[Jaakko Karrenpalo]

Add unit tests for the PRP duplicate detection

Signed-off-by: Jaakko Karrenpalo <jkarrenpalo@gmail.com>
---
Changes in v2:
- Changed KUnit tests to compile as built-in only
Changes in v3:
- Changed the KUnit tests to compile as a module

 net/hsr/Kconfig                |  18 +++
 net/hsr/Makefile               |   2 +
 net/hsr/hsr_framereg.c         |   4 +
 net/hsr/prp_dup_discard_test.c | 212 +++++++++++++++++++++++++++++++++
 4 files changed, 236 insertions(+)
 create mode 100644 net/hsr/prp_dup_discard_test.c

diff --git a/net/hsr/Kconfig b/net/hsr/Kconfig
index 1b048c17b6c8..fcacdf4f0ffc 100644
--- a/net/hsr/Kconfig
+++ b/net/hsr/Kconfig
@@ -38,3 +38,21 @@ config HSR
 	  relying on this code in a safety critical system!
 
 	  If unsure, say N.
+
+if HSR
+
+config PRP_DUP_DISCARD_KUNIT_TEST
+	tristate "PRP duplicate discard KUnit tests" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  Covers the PRP duplicate discard algorithm.
+	  Only useful for kernel devs running KUnit test harness and are not
+	  for inclusion into a production build.
+
+	  For more information on KUnit and unit tests in general please refer
+	  to the KUnit documentation in Documentation/dev-tools/kunit/.
+
+	  If unsure, say N.
+
+endif
diff --git a/net/hsr/Makefile b/net/hsr/Makefile
index 75df90d3b416..34e581db5c41 100644
--- a/net/hsr/Makefile
+++ b/net/hsr/Makefile
@@ -8,3 +8,5 @@ obj-$(CONFIG_HSR)	+= hsr.o
 hsr-y			:= hsr_main.o hsr_framereg.o hsr_device.o \
 			   hsr_netlink.o hsr_slave.o hsr_forward.o
 hsr-$(CONFIG_DEBUG_FS) += hsr_debugfs.o
+
+obj-$(CONFIG_PRP_DUP_DISCARD_KUNIT_TEST) += prp_dup_discard_test.o
diff --git a/net/hsr/hsr_framereg.c b/net/hsr/hsr_framereg.c
index 79e066422044..3192e1253715 100644
--- a/net/hsr/hsr_framereg.c
+++ b/net/hsr/hsr_framereg.c
@@ -588,6 +588,10 @@ int prp_register_frame_out(struct hsr_port *port, struct hsr_frame_info *frame)
 	return 0;
 }
 
+#ifdef CONFIG_PRP_DUP_DISCARD_KUNIT_TEST_MODULE
+EXPORT_SYMBOL(prp_register_frame_out);
+#endif
+
 static struct hsr_port *get_late_port(struct hsr_priv *hsr,
 				      struct hsr_node *node)
 {
diff --git a/net/hsr/prp_dup_discard_test.c b/net/hsr/prp_dup_discard_test.c
new file mode 100644
index 000000000000..e86b7b633ae8
--- /dev/null
+++ b/net/hsr/prp_dup_discard_test.c
@@ -0,0 +1,212 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <kunit/test.h>
+
+#include "hsr_main.h"
+#include "hsr_framereg.h"
+
+struct prp_test_data {
+	struct hsr_port port;
+	struct hsr_port port_rcv;
+	struct hsr_frame_info frame;
+	struct hsr_node node;
+};
+
+static struct prp_test_data *build_prp_test_data(struct kunit *test)
+{
+	struct prp_test_data *data = kunit_kzalloc(test,
+		sizeof(struct prp_test_data), GFP_USER);
+	KUNIT_EXPECT_NOT_ERR_OR_NULL(test, data);
+
+	data->frame.node_src = &data->node;
+	data->frame.port_rcv = &data->port_rcv;
+	data->port_rcv.type = HSR_PT_SLAVE_A;
+	data->node.seq_start[HSR_PT_SLAVE_A] = 1;
+	data->node.seq_expected[HSR_PT_SLAVE_A] = 1;
+	data->node.seq_start[HSR_PT_SLAVE_B] = 1;
+	data->node.seq_expected[HSR_PT_SLAVE_B] = 1;
+	data->node.seq_out[HSR_PT_MASTER] = 0;
+	data->node.time_out[HSR_PT_MASTER] = jiffies;
+	data->port.type = HSR_PT_MASTER;
+
+	return data;
+}
+
+static void check_prp_counters(struct kunit *test,
+			       struct prp_test_data *data,
+			       u16 seq_start_a, u16 seq_expected_a,
+			       u16 seq_start_b, u16 seq_expected_b)
+{
+	KUNIT_EXPECT_EQ(test, data->node.seq_start[HSR_PT_SLAVE_A],
+			seq_start_a);
+	KUNIT_EXPECT_EQ(test, data->node.seq_start[HSR_PT_SLAVE_B],
+			seq_start_b);
+	KUNIT_EXPECT_EQ(test, data->node.seq_expected[HSR_PT_SLAVE_A],
+			seq_expected_a);
+	KUNIT_EXPECT_EQ(test, data->node.seq_expected[HSR_PT_SLAVE_B],
+			seq_expected_b);
+}
+
+static void prp_dup_discard_forward(struct kunit *test)
+{
+	/* Normal situation, both LANs in sync. Next frame is forwarded */
+	struct prp_test_data *data = build_prp_test_data(test);
+
+	data->frame.sequence_nr = 2;
+	KUNIT_EXPECT_EQ(test, 0,
+			prp_register_frame_out(&data->port, &data->frame));
+	KUNIT_EXPECT_EQ(test, data->frame.sequence_nr,
+			data->node.seq_out[HSR_PT_MASTER]);
+	KUNIT_EXPECT_EQ(test, jiffies, data->node.time_out[HSR_PT_MASTER]);
+	check_prp_counters(test, data, data->frame.sequence_nr,
+			   data->frame.sequence_nr + 1, 1, 1);
+}
+
+static void prp_dup_discard_inside_dropwindow(struct kunit *test)
+{
+	/* Normal situation, other LAN ahead by one. Frame is dropped */
+	struct prp_test_data *data = build_prp_test_data(test);
+	unsigned long time = jiffies - 10;
+
+	data->frame.sequence_nr = 1;
+	data->node.seq_expected[HSR_PT_SLAVE_B] = 3;
+	data->node.seq_out[HSR_PT_MASTER] = 2;
+	data->node.time_out[HSR_PT_MASTER] = time;
+
+	KUNIT_EXPECT_EQ(test, 1,
+			prp_register_frame_out(&data->port, &data->frame));
+	KUNIT_EXPECT_EQ(test, 2, data->node.seq_out[HSR_PT_MASTER]);
+	KUNIT_EXPECT_EQ(test, time, data->node.time_out[HSR_PT_MASTER]);
+	check_prp_counters(test, data, 2, 2, 2, 3);
+}
+
+static void prp_dup_discard_node_timeout(struct kunit *test)
+{
+	/* Timeout situation, node hasn't sent anything for a while */
+	struct prp_test_data *data = build_prp_test_data(test);
+
+	data->frame.sequence_nr = 7;
+	data->node.seq_start[HSR_PT_SLAVE_A] = 1234;
+	data->node.seq_expected[HSR_PT_SLAVE_A] = 1235;
+	data->node.seq_start[HSR_PT_SLAVE_B] = 1234;
+	data->node.seq_expected[HSR_PT_SLAVE_B] = 1234;
+	data->node.seq_out[HSR_PT_MASTER] = 1234;
+	data->node.time_out[HSR_PT_MASTER] =
+		jiffies - msecs_to_jiffies(HSR_ENTRY_FORGET_TIME) - 1;
+
+	KUNIT_EXPECT_EQ(test, 0,
+			prp_register_frame_out(&data->port, &data->frame));
+	KUNIT_EXPECT_EQ(test, data->frame.sequence_nr,
+			data->node.seq_out[HSR_PT_MASTER]);
+	KUNIT_EXPECT_EQ(test, jiffies, data->node.time_out[HSR_PT_MASTER]);
+	check_prp_counters(test, data, data->frame.sequence_nr,
+			   data->frame.sequence_nr + 1, 1234, 1234);
+}
+
+static void prp_dup_discard_out_of_sequence(struct kunit *test)
+{
+	/* One frame is received out of sequence on both LANs */
+	struct prp_test_data *data = build_prp_test_data(test);
+
+	data->node.seq_start[HSR_PT_SLAVE_A] = 10;
+	data->node.seq_expected[HSR_PT_SLAVE_A] = 10;
+	data->node.seq_start[HSR_PT_SLAVE_B] = 10;
+	data->node.seq_expected[HSR_PT_SLAVE_B] = 10;
+	data->node.seq_out[HSR_PT_MASTER] = 9;
+
+	/* 1st old frame, should be accepted */
+	data->frame.sequence_nr = 8;
+	KUNIT_EXPECT_EQ(test, 0,
+			prp_register_frame_out(&data->port, &data->frame));
+	KUNIT_EXPECT_EQ(test, data->frame.sequence_nr,
+			data->node.seq_out[HSR_PT_MASTER]);
+	check_prp_counters(test, data, data->frame.sequence_nr,
+			   data->frame.sequence_nr + 1, 10, 10);
+
+	/* 2nd frame should be dropped */
+	data->frame.sequence_nr = 8;
+	data->port_rcv.type = HSR_PT_SLAVE_B;
+	KUNIT_EXPECT_EQ(test, 1,
+			prp_register_frame_out(&data->port, &data->frame));
+	check_prp_counters(test, data, data->frame.sequence_nr + 1,
+			   data->frame.sequence_nr + 1,
+			   data->frame.sequence_nr + 1,
+			   data->frame.sequence_nr + 1);
+
+	/* Next frame, this is forwarded */
+	data->frame.sequence_nr = 10;
+	data->port_rcv.type = HSR_PT_SLAVE_A;
+	KUNIT_EXPECT_EQ(test, 0,
+			prp_register_frame_out(&data->port, &data->frame));
+	KUNIT_EXPECT_EQ(test, data->frame.sequence_nr,
+			data->node.seq_out[HSR_PT_MASTER]);
+	check_prp_counters(test, data, data->frame.sequence_nr,
+			   data->frame.sequence_nr + 1, 9, 9);
+
+	/* and next one is dropped */
+	data->frame.sequence_nr = 10;
+	data->port_rcv.type = HSR_PT_SLAVE_B;
+	KUNIT_EXPECT_EQ(test, 1,
+			prp_register_frame_out(&data->port, &data->frame));
+	check_prp_counters(test, data, data->frame.sequence_nr + 1,
+			   data->frame.sequence_nr + 1,
+			   data->frame.sequence_nr + 1,
+			   data->frame.sequence_nr + 1);
+}
+
+static void prp_dup_discard_lan_b_late(struct kunit *test)
+{
+	/* LAN B is behind */
+	struct prp_test_data *data = build_prp_test_data(test);
+
+	data->node.seq_start[HSR_PT_SLAVE_A] = 9;
+	data->node.seq_expected[HSR_PT_SLAVE_A] = 9;
+	data->node.seq_start[HSR_PT_SLAVE_B] = 9;
+	data->node.seq_expected[HSR_PT_SLAVE_B] = 9;
+	data->node.seq_out[HSR_PT_MASTER] = 8;
+
+	data->frame.sequence_nr = 9;
+	KUNIT_EXPECT_EQ(test, 0,
+			prp_register_frame_out(&data->port, &data->frame));
+	KUNIT_EXPECT_EQ(test, data->frame.sequence_nr,
+			data->node.seq_out[HSR_PT_MASTER]);
+	check_prp_counters(test, data, 9, 10, 9, 9);
+
+	data->frame.sequence_nr = 10;
+	KUNIT_EXPECT_EQ(test, 0,
+			prp_register_frame_out(&data->port, &data->frame));
+	KUNIT_EXPECT_EQ(test, data->frame.sequence_nr,
+			data->node.seq_out[HSR_PT_MASTER]);
+	check_prp_counters(test, data, 9, 11, 9, 9);
+
+	data->frame.sequence_nr = 9;
+	data->port_rcv.type = HSR_PT_SLAVE_B;
+	KUNIT_EXPECT_EQ(test, 1,
+			prp_register_frame_out(&data->port, &data->frame));
+	check_prp_counters(test, data, 10, 11, 10, 10);
+
+	data->frame.sequence_nr = 10;
+	data->port_rcv.type = HSR_PT_SLAVE_B;
+	KUNIT_EXPECT_EQ(test, 1,
+			prp_register_frame_out(&data->port, &data->frame));
+	check_prp_counters(test, data,  11, 11, 11, 11);
+}
+
+static struct kunit_case prp_dup_discard_test_cases[] = {
+	KUNIT_CASE(prp_dup_discard_forward),
+	KUNIT_CASE(prp_dup_discard_inside_dropwindow),
+	KUNIT_CASE(prp_dup_discard_node_timeout),
+	KUNIT_CASE(prp_dup_discard_out_of_sequence),
+	KUNIT_CASE(prp_dup_discard_lan_b_late),
+	{}
+};
+
+static struct kunit_suite prp_dup_discard_suite = {
+	.name = "prp_duplicate_discard",
+	.test_cases = prp_dup_discard_test_cases,
+};
+
+kunit_test_suite(prp_dup_discard_suite);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("KUnit tests for PRP duplicate discard");
+MODULE_AUTHOR("Jaakko Karrenpalo <jkarrenpalo@gmail.com>");
-- 
2.43.0

Re: [PATCH net-next v3 1/2] net: hsr: Fix PRP duplicate detection

[Simon Horman]

On Thu, Feb 27, 2025 at 07:09:22AM +0200, Jaakko Karrenpalo wrote:
> Add PRP specific function for handling duplicate
> packets. This is needed because of potential
> L2 802.1p prioritization done by network switches.
> 
> The L2 prioritization can re-order the PRP packets
> from a node causing the existing implementation to
> discard the frame(s) that have been received 'late'
> because the sequence number is before the previous
> received packet. This can happen if the node is
> sending multiple frames back-to-back with different
> priority.
> 
> Signed-off-by: Jaakko Karrenpalo <jkarrenpalo@gmail.com>
> ---
> Changes in v3:
> - Fixed indentation
> - Renamed local variables

Thanks, I see that this addresses Paolo's review of v2
and overall looks good to me.

Reviewed-by: Simon Horman <horms@kernel.org>

Please find below two minor nits.
I don't think you need to respin because of them.
But do consider addressing them if there is a new
revision for some other reason.

...

> diff --git a/net/hsr/hsr_framereg.c b/net/hsr/hsr_framereg.c

...

> +/* Adaptation of the PRP duplicate discard algorithm described in wireshark
> + * wiki (https://wiki.wireshark.org/PRP)
> + *
> + * A drop window is maintained for both LANs with start sequence set to the
> + * first sequence accepted on the LAN that has not been seen on the other LAN,
> + * and expected sequence set to the latest received sequence number plus one.
> + *
> + * When a frame is received on either LAN it is compared against the received
> + * frames on the other LAN. If it is outside the drop window of the other LAN
> + * the frame is accepted and the drop window is updated.
> + * The drop window for the other LAN is reset.
> + *
> + * 'port' is the outgoing interface
> + * 'frame' is the frame to be sent
> + *
> + * Return:
> + *	 1 if frame can be shown to have been sent recently on this interface,
> + *	 0 otherwise
> + */
> +int prp_register_frame_out(struct hsr_port *port, struct hsr_frame_info *frame)
> +{
> +	enum hsr_port_type other_port;
> +	enum hsr_port_type rcv_port;
> +	struct hsr_node *node;
> +	u16 sequence_diff;
> +	u16 sequence_exp;
> +	u16 sequence_nr;
> +
> +	/* out-going frames are always in order
> +	 *and can be checked the same way as for HSR

nit: space between '*' and 'and'.

> +	 */
> +	if (frame->port_rcv->type == HSR_PT_MASTER)
> +		return hsr_register_frame_out(port, frame);
> +
> +	/* for PRP we should only forward frames from the slave ports
> +	 * to the master port
> +	 */
> +	if (port->type != HSR_PT_MASTER)
> +		return 1;
> +
> +	node = frame->node_src;
> +	sequence_nr = frame->sequence_nr;
> +	sequence_exp = sequence_nr + 1;
> +	rcv_port = frame->port_rcv->type;
> +	other_port =
> +		rcv_port == HSR_PT_SLAVE_A ? HSR_PT_SLAVE_B : HSR_PT_SLAVE_A;
> +
> +	spin_lock_bh(&node->seq_out_lock);
> +	if (time_is_before_jiffies(node->time_out[port->type] +
> +	    msecs_to_jiffies(HSR_ENTRY_FORGET_TIME)) ||
> +	    (node->seq_start[rcv_port] == node->seq_expected[rcv_port] &&
> +	    node->seq_start[other_port] == node->seq_expected[other_port])) {

nit: the line above should be indented to align with the inside of the
     parentheses on the preceding line.

	    (node->seq_start[rcv_port] == node->seq_expected[rcv_port] &&
	     node->seq_start[other_port] == node->seq_expected[other_port])) {

> +		/* the node hasn't been sending for a while
> +		 * or both drop windows are empty, forward the frame
> +		 */
> +		node->seq_start[rcv_port] = sequence_nr;
> +	} else if (seq_nr_before(sequence_nr, node->seq_expected[other_port]) &&
> +		   seq_nr_before_or_eq(node->seq_start[other_port], sequence_nr)) {
> +		/* drop the frame, update the drop window for the other port
> +		 * and reset our drop window
> +		 */
> +		node->seq_start[other_port] = sequence_exp;
> +		node->seq_expected[rcv_port] = sequence_exp;
> +		node->seq_start[rcv_port] = node->seq_expected[rcv_port];
> +		spin_unlock_bh(&node->seq_out_lock);
> +		return 1;
> +	}
> +
> +	/* update the drop window for the port where this frame was received
> +	 * and clear the drop window for the other port
> +	 */
> +	node->seq_start[other_port] = node->seq_expected[other_port];
> +	node->seq_expected[rcv_port] = sequence_exp;
> +	sequence_diff = sequence_exp - node->seq_start[rcv_port];
> +	if (sequence_diff > PRP_DROP_WINDOW_LEN)
> +		node->seq_start[rcv_port] = sequence_exp - PRP_DROP_WINDOW_LEN;
> +
> +	node->time_out[port->type] = jiffies;
> +	node->seq_out[port->type] = sequence_nr;
> +	spin_unlock_bh(&node->seq_out_lock);
> +	return 0;
> +}
> +
>  static struct hsr_port *get_late_port(struct hsr_priv *hsr,
>  				      struct hsr_node *node)
>  {

Re: [PATCH net-next v3 2/2] net: hsr: Add KUnit test for PRP

[Simon Horman]

On Thu, Feb 27, 2025 at 07:09:23AM +0200, Jaakko Karrenpalo wrote:
> Add unit tests for the PRP duplicate detection
> 
> Signed-off-by: Jaakko Karrenpalo <jkarrenpalo@gmail.com>
> ---
> Changes in v2:
> - Changed KUnit tests to compile as built-in only
> Changes in v3:
> - Changed the KUnit tests to compile as a module

Thanks, I see that this addresses Paolo's review of v2
and overall looks good to me.

Reviewed-by: Simon Horman <horms@kernel.org>

Re: [PATCH net-next v3 2/2] net: hsr: Add KUnit test for PRP

[Paolo Abeni]

On 2/27/25 6:09 AM, Jaakko Karrenpalo wrote:
> Add unit tests for the PRP duplicate detection
> 
> Signed-off-by: Jaakko Karrenpalo <jkarrenpalo@gmail.com>
> ---
> Changes in v2:
> - Changed KUnit tests to compile as built-in only
> Changes in v3:
> - Changed the KUnit tests to compile as a module
> 
>  net/hsr/Kconfig                |  18 +++
>  net/hsr/Makefile               |   2 +
>  net/hsr/hsr_framereg.c         |   4 +
>  net/hsr/prp_dup_discard_test.c | 212 +++++++++++++++++++++++++++++++++
>  4 files changed, 236 insertions(+)
>  create mode 100644 net/hsr/prp_dup_discard_test.c
> 
> diff --git a/net/hsr/Kconfig b/net/hsr/Kconfig
> index 1b048c17b6c8..fcacdf4f0ffc 100644
> --- a/net/hsr/Kconfig
> +++ b/net/hsr/Kconfig
> @@ -38,3 +38,21 @@ config HSR
>  	  relying on this code in a safety critical system!
>  
>  	  If unsure, say N.
> +
> +if HSR
> +
> +config PRP_DUP_DISCARD_KUNIT_TEST
> +	tristate "PRP duplicate discard KUnit tests" if !KUNIT_ALL_TESTS
> +	depends on KUNIT
> +	default KUNIT_ALL_TESTS
> +	help
> +	  Covers the PRP duplicate discard algorithm.
> +	  Only useful for kernel devs running KUnit test harness and are not
> +	  for inclusion into a production build.
> +
> +	  For more information on KUnit and unit tests in general please refer
> +	  to the KUnit documentation in Documentation/dev-tools/kunit/.
> +
> +	  If unsure, say N.
> +
> +endif
> diff --git a/net/hsr/Makefile b/net/hsr/Makefile
> index 75df90d3b416..34e581db5c41 100644
> --- a/net/hsr/Makefile
> +++ b/net/hsr/Makefile
> @@ -8,3 +8,5 @@ obj-$(CONFIG_HSR)	+= hsr.o
>  hsr-y			:= hsr_main.o hsr_framereg.o hsr_device.o \
>  			   hsr_netlink.o hsr_slave.o hsr_forward.o
>  hsr-$(CONFIG_DEBUG_FS) += hsr_debugfs.o
> +
> +obj-$(CONFIG_PRP_DUP_DISCARD_KUNIT_TEST) += prp_dup_discard_test.o
> diff --git a/net/hsr/hsr_framereg.c b/net/hsr/hsr_framereg.c
> index 79e066422044..3192e1253715 100644
> --- a/net/hsr/hsr_framereg.c
> +++ b/net/hsr/hsr_framereg.c
> @@ -588,6 +588,10 @@ int prp_register_frame_out(struct hsr_port *port, struct hsr_frame_info *frame)
>  	return 0;
>  }
>  
> +#ifdef CONFIG_PRP_DUP_DISCARD_KUNIT_TEST_MODULE

The more idiomatic way to express the above is:

#if IS_MODULE(CONFIG_PRP_DUP_DISCARD_KUNIT_TEST)

Otherwise LGTM,

Paolo

Re: [PATCH net-next v3 1/2] net: hsr: Fix PRP duplicate detection

[Paolo Abeni]

On 2/27/25 6:09 AM, Jaakko Karrenpalo wrote:
> +int prp_register_frame_out(struct hsr_port *port, struct hsr_frame_info *frame)
> +{
> +	enum hsr_port_type other_port;
> +	enum hsr_port_type rcv_port;
> +	struct hsr_node *node;
> +	u16 sequence_diff;
> +	u16 sequence_exp;
> +	u16 sequence_nr;
> +
> +	/* out-going frames are always in order
> +	 *and can be checked the same way as for HSR
> +	 */
> +	if (frame->port_rcv->type == HSR_PT_MASTER)
> +		return hsr_register_frame_out(port, frame);
> +
> +	/* for PRP we should only forward frames from the slave ports
> +	 * to the master port
> +	 */
> +	if (port->type != HSR_PT_MASTER)
> +		return 1;
> +
> +	node = frame->node_src;
> +	sequence_nr = frame->sequence_nr;
> +	sequence_exp = sequence_nr + 1;
> +	rcv_port = frame->port_rcv->type;
> +	other_port =
> +		rcv_port == HSR_PT_SLAVE_A ? HSR_PT_SLAVE_B : HSR_PT_SLAVE_A;

I'm again surprised checkpatch did not complain WRT the above. Please
reformat it as:

	other_port = rcv_port == HSR_PT_SLAVE_A ? HSR_PT_SLAVE_B :
						  HSR_PT_SLAVE_A;

Also, please address the other things mentioned by Simon.

Note: you can retain Simon's tag in next iteration.

Thanks,

Paolo