Merge branch 'fix-netdevim-to-correctly-mark-napi-ids'

Joe Damato says:

====================
Fix netdevim to correctly mark NAPI IDs

This series fixes netdevsim to correctly set the NAPI ID on the skb.
This is helpful for writing tests around features that use
SO_INCOMING_NAPI_ID.

In addition to the netdevsim fix in patch 1, patches 2 & 3 do some self
test refactoring and add a test for NAPI IDs. The test itself (patch 3)
introduces a C helper because apparently python doesn't have
socket.SO_INCOMING_NAPI_ID.

v3: https://lore.kernel.org/20250418013719.12094-1-jdamato@fastly.com
v2: https://lore.kernel.org/20250417013301.39228-1-jdamato@fastly.com
rfcv1: https://lore.kernel.org/20250329000030.39543-1-jdamato@fastly.com
====================

Link: https://patch.msgid.link/20250424002746.16891-1-jdamato@fastly.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

7 files changed, 172 insertions, 48 deletions

diff --git a/drivers/net/netdevsim/netdev.c b/drivers/net/netdevsim/netdev.c
index 0e0321a7ddd7..2aa999345fe1 100644
--- a/drivers/net/netdevsim/netdev.c
+++ b/drivers/net/netdevsim/netdev.c
@@ -29,6 +29,7 @@
 #include <net/pkt_cls.h>
 #include <net/rtnetlink.h>
 #include <net/udp_tunnel.h>
+#include <net/busy_poll.h>
 
 #include "netdevsim.h"
 
@@ -357,6 +358,7 @@ static int nsim_rcv(struct nsim_rq *rq, int budget)
 			break;
 
 		skb = skb_dequeue(&rq->skb_queue);
+		skb_mark_napi_id(skb, &rq->napi);
 		netif_receive_skb(skb);
 	}
 
diff --git a/tools/testing/selftests/drivers/net/.gitignore b/tools/testing/selftests/drivers/net/.gitignore
index ec746f374e85..72d2124fd513 100644
--- a/tools/testing/selftests/drivers/net/.gitignore
+++ b/tools/testing/selftests/drivers/net/.gitignore
@@ -1,2 +1,3 @@
 # SPDX-License-Identifier: GPL-2.0-only
+napi_id_helper
 xdp_helper
diff --git a/tools/testing/selftests/drivers/net/Makefile b/tools/testing/selftests/drivers/net/Makefile
index 0c95bd944d56..47247c2ef948 100644
--- a/tools/testing/selftests/drivers/net/Makefile
+++ b/tools/testing/selftests/drivers/net/Makefile
@@ -6,9 +6,13 @@ TEST_INCLUDES := $(wildcard lib/py/*.py) \
 		 ../../net/net_helper.sh \
 		 ../../net/lib.sh \
 
-TEST_GEN_FILES := xdp_helper
+TEST_GEN_FILES := \
+	napi_id_helper \
+	xdp_helper \
+# end of TEST_GEN_FILES
 
 TEST_PROGS := \
+	napi_id.py \
 	netcons_basic.sh \
 	netcons_fragmented_msg.sh \
 	netcons_overflow.sh \
diff --git a/tools/testing/selftests/drivers/net/ksft.h b/tools/testing/selftests/drivers/net/ksft.h
new file mode 100644
index 000000000000..17dc34a612c6
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/ksft.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#if !defined(__NET_KSFT_H__)
+#define __NET_KSFT_H__
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+static inline void ksft_ready(void)
+{
+	const char msg[7] = "ready\n";
+	char *env_str;
+	int fd;
+
+	env_str = getenv("KSFT_READY_FD");
+	if (env_str) {
+		fd = atoi(env_str);
+		if (!fd) {
+			fprintf(stderr, "invalid KSFT_READY_FD = '%s'\n",
+				env_str);
+			return;
+		}
+	} else {
+		fd = STDOUT_FILENO;
+	}
+
+	write(fd, msg, sizeof(msg));
+	if (fd != STDOUT_FILENO)
+		close(fd);
+}
+
+static inline void ksft_wait(void)
+{
+	char *env_str;
+	char byte;
+	int fd;
+
+	env_str = getenv("KSFT_WAIT_FD");
+	if (env_str) {
+		fd = atoi(env_str);
+		if (!fd) {
+			fprintf(stderr, "invalid KSFT_WAIT_FD = '%s'\n",
+				env_str);
+			return;
+		}
+	} else {
+		/* Not running in KSFT env, wait for input from STDIN instead */
+		fd = STDIN_FILENO;
+	}
+
+	read(fd, &byte, sizeof(byte));
+	if (fd != STDIN_FILENO)
+		close(fd);
+}
+
+#endif
diff --git a/tools/testing/selftests/drivers/net/napi_id.py b/tools/testing/selftests/drivers/net/napi_id.py
new file mode 100755
index 000000000000..356bac46ba04
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/napi_id.py
@@ -0,0 +1,23 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+
+from lib.py import ksft_run, ksft_exit
+from lib.py import ksft_eq, NetDrvEpEnv
+from lib.py import bkg, cmd, rand_port, NetNSEnter
+
+def test_napi_id(cfg) -> None:
+    port = rand_port()
+    listen_cmd = f"{cfg.test_dir}/napi_id_helper {cfg.addr_v['4']} {port}"
+
+    with bkg(listen_cmd, ksft_wait=3) as server:
+        cmd(f"echo a | socat - TCP:{cfg.addr_v['4']}:{port}", host=cfg.remote, shell=True)
+
+    ksft_eq(0, server.ret)
+
+def main() -> None:
+    with NetDrvEpEnv(__file__) as cfg:
+        ksft_run([test_napi_id], args=(cfg,))
+    ksft_exit()
+
+if __name__ == "__main__":
+    main()
diff --git a/tools/testing/selftests/drivers/net/napi_id_helper.c b/tools/testing/selftests/drivers/net/napi_id_helper.c
new file mode 100644
index 000000000000..7e8e7d373b61
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/napi_id_helper.c
@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <arpa/inet.h>
+#include <sys/socket.h>
+
+#include "ksft.h"
+
+int main(int argc, char *argv[])
+{
+	struct sockaddr_in address;
+	unsigned int napi_id;
+	unsigned int port;
+	socklen_t optlen;
+	char buf[1024];
+	int opt = 1;
+	int server;
+	int client;
+	int ret;
+
+	server = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
+	if (server < 0) {
+		perror("socket creation failed");
+		if (errno == EAFNOSUPPORT)
+			return -1;
+		return 1;
+	}
+
+	port = atoi(argv[2]);
+
+	if (setsockopt(server, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt))) {
+		perror("setsockopt");
+		return 1;
+	}
+
+	address.sin_family = AF_INET;
+	inet_pton(AF_INET, argv[1], &address.sin_addr);
+	address.sin_port = htons(port);
+
+	if (bind(server, (struct sockaddr *)&address, sizeof(address)) < 0) {
+		perror("bind failed");
+		return 1;
+	}
+
+	if (listen(server, 1) < 0) {
+		perror("listen");
+		return 1;
+	}
+
+	ksft_ready();
+
+	client = accept(server, NULL, 0);
+	if (client < 0) {
+		perror("accept");
+		return 1;
+	}
+
+	optlen = sizeof(napi_id);
+	ret = getsockopt(client, SOL_SOCKET, SO_INCOMING_NAPI_ID, &napi_id,
+			 &optlen);
+	if (ret != 0) {
+		perror("getsockopt");
+		return 1;
+	}
+
+	read(client, buf, 1024);
+
+	ksft_wait();
+
+	if (napi_id == 0) {
+		fprintf(stderr, "napi ID is 0\n");
+		return 1;
+	}
+
+	close(client);
+	close(server);
+
+	return 0;
+}
diff --git a/tools/testing/selftests/drivers/net/xdp_helper.c b/tools/testing/selftests/drivers/net/xdp_helper.c
index aeed25914104..d5bb8ac33efa 100644
--- a/tools/testing/selftests/drivers/net/xdp_helper.c
+++ b/tools/testing/selftests/drivers/net/xdp_helper.c
@@ -11,56 +11,11 @@
 #include <net/if.h>
 #include <inttypes.h>
 
+#include "ksft.h"
+
 #define UMEM_SZ (1U << 16)
 #define NUM_DESC (UMEM_SZ / 2048)
 
-/* Move this to a common header when reused! */
-static void ksft_ready(void)
-{
-	const char msg[7] = "ready\n";
-	char *env_str;
-	int fd;
-
-	env_str = getenv("KSFT_READY_FD");
-	if (env_str) {
-		fd = atoi(env_str);
-		if (!fd) {
-			fprintf(stderr, "invalid KSFT_READY_FD = '%s'\n",
-				env_str);
-			return;
-		}
-	} else {
-		fd = STDOUT_FILENO;
-	}
-
-	write(fd, msg, sizeof(msg));
-	if (fd != STDOUT_FILENO)
-		close(fd);
-}
-
-static void ksft_wait(void)
-{
-	char *env_str;
-	char byte;
-	int fd;
-
-	env_str = getenv("KSFT_WAIT_FD");
-	if (env_str) {
-		fd = atoi(env_str);
-		if (!fd) {
-			fprintf(stderr, "invalid KSFT_WAIT_FD = '%s'\n",
-				env_str);
-			return;
-		}
-	} else {
-		/* Not running in KSFT env, wait for input from STDIN instead */
-		fd = STDIN_FILENO;
-	}
-
-	read(fd, &byte, sizeof(byte));
-	if (fd != STDIN_FILENO)
-		close(fd);
-}
 
 /* this is a simple helper program that creates an XDP socket and does the
  * minimum necessary to get bind() to succeed.