[PATCH net-next v4 0/3] Fix netdevim to correctly mark NAPI IDs

[PATCH net-next v4 0/3] Fix netdevim to correctly mark NAPI IDs

[Joe Damato]

Greetings:

Welcome to v4.

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.

Thanks,
Joe

v4:
  - Updated the macro guard in patch 2
  - Removed the remote deploy from patch 3

v3: https://lore.kernel.org/netdev/20250418013719.12094-1-jdamato@fastly.com/
  - Dropped patch 3 from v2 as it is no longer necessary.
  - Patch 3 from this series (which was patch 4 in the v2)
    - Sorted .gitignore alphabetically
    - added cfg.remote_deploy so the test supports real remote machines
    - Dropped the NetNSEnter as it is unnecessary
    - Fixed a string interpolation issue that Paolo hit with his Python
      version

v2: https://lore.kernel.org/netdev/20250417013301.39228-1-jdamato@fastly.com/
  - No longer an RFC
  - Minor whitespace change in patch 1 (no functional change).
  - Patches 2-4 new in v2

rfcv1: https://lore.kernel.org/netdev/20250329000030.39543-1-jdamato@fastly.com/


Joe Damato (3):
  netdevsim: Mark NAPI ID on skb in nsim_rcv
  selftests: drv-net: Factor out ksft C helpers
  selftests: drv-net: Test that NAPI ID is non-zero

 drivers/net/netdevsim/netdev.c                |  2 +
 .../testing/selftests/drivers/net/.gitignore  |  1 +
 tools/testing/selftests/drivers/net/Makefile  |  6 +-
 tools/testing/selftests/drivers/net/ksft.h    | 56 +++++++++++++
 .../testing/selftests/drivers/net/napi_id.py  | 23 +++++
 .../selftests/drivers/net/napi_id_helper.c    | 83 +++++++++++++++++++
 .../selftests/drivers/net/xdp_helper.c        | 49 +----------
 7 files changed, 172 insertions(+), 48 deletions(-)
 create mode 100644 tools/testing/selftests/drivers/net/ksft.h
 create mode 100755 tools/testing/selftests/drivers/net/napi_id.py
 create mode 100644 tools/testing/selftests/drivers/net/napi_id_helper.c


base-commit: cd7276ecac9c64c80433fbcff2e35aceaea6f477
-- 
2.43.0

[PATCH net-next v4 1/3] netdevsim: Mark NAPI ID on skb in nsim_rcv

[Joe Damato]

Previously, nsim_rcv was not marking the NAPI ID on the skb, leading to
applications seeing a napi ID of 0 when using SO_INCOMING_NAPI_ID.

To add to the userland confusion, netlink appears to correctly report
the NAPI IDs for netdevsim queues but the resulting file descriptor from
a call to accept() was reporting a NAPI ID of 0.

Signed-off-by: Joe Damato <jdamato@fastly.com>
---
 drivers/net/netdevsim/netdev.c | 2 ++
 1 file changed, 2 insertions(+)

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);
 	}
 
-- 
2.43.0

[PATCH net-next v4 2/3] selftests: drv-net: Factor out ksft C helpers

[Joe Damato]

Factor ksft C helpers to a header so they can be used by other C-based
tests.

Signed-off-by: Joe Damato <jdamato@fastly.com>
---
 tools/testing/selftests/drivers/net/ksft.h    | 56 +++++++++++++++++++
 .../selftests/drivers/net/xdp_helper.c        | 49 +---------------
 2 files changed, 58 insertions(+), 47 deletions(-)
 create mode 100644 tools/testing/selftests/drivers/net/ksft.h

diff --git a/tools/testing/selftests/drivers/net/ksft.h b/tools/testing/selftests/drivers/net/ksft.h
new file mode 100644
index 000000000000..c30a02da903f
--- /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 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);
+}
+
+#endif
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.
-- 
2.43.0

[PATCH net-next v4 3/3] selftests: drv-net: Test that NAPI ID is non-zero

[Joe Damato]

Test that the SO_INCOMING_NAPI_ID of a network file descriptor is
non-zero. This ensures that either the core networking stack or, in some
cases like netdevsim, the driver correctly sets the NAPI ID.

Signed-off-by: Joe Damato <jdamato@fastly.com>
---
 .../testing/selftests/drivers/net/.gitignore  |  1 +
 tools/testing/selftests/drivers/net/Makefile  |  6 +-
 .../testing/selftests/drivers/net/napi_id.py  | 23 +++++
 .../selftests/drivers/net/napi_id_helper.c    | 83 +++++++++++++++++++
 4 files changed, 112 insertions(+), 1 deletion(-)
 create mode 100755 tools/testing/selftests/drivers/net/napi_id.py
 create mode 100644 tools/testing/selftests/drivers/net/napi_id_helper.c

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/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;
+}
-- 
2.43.0

Re: [PATCH net-next v4 2/3] selftests: drv-net: Factor out ksft C helpers

[Jakub Kicinski]

On Thu, 24 Apr 2025 00:27:32 +0000 Joe Damato wrote:
> +++ b/tools/testing/selftests/drivers/net/ksft.h
> +static void ksft_ready(void)

> +static void ksft_wait(void)

These need to be static inlines.
I'll fix when applying cause I think this series may conflict 
with Bui Quang Minh's

Re: [PATCH net-next v4 2/3] selftests: drv-net: Factor out ksft C helpers

[Joe Damato]

On Thu, Apr 24, 2025 at 06:32:18PM -0700, Jakub Kicinski wrote:
> On Thu, 24 Apr 2025 00:27:32 +0000 Joe Damato wrote:
> > +++ b/tools/testing/selftests/drivers/net/ksft.h
> > +static void ksft_ready(void)
> 
> > +static void ksft_wait(void)
> 
> These need to be static inlines.
> I'll fix when applying cause I think this series may conflict 
> with Bui Quang Minh's

OK -- if you change your mind and prefer that I respin to save you
some cycles or something, I am happy to do so.

Thanks.

Re: [PATCH net-next v4 0/3] Fix netdevim to correctly mark NAPI IDs

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Thu, 24 Apr 2025 00:27:30 +0000 you wrote:
> Greetings:
> 
> Welcome to v4.
> 
> 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.
> 
> [...]

Here is the summary with links:
  - [net-next,v4,1/3] netdevsim: Mark NAPI ID on skb in nsim_rcv
    https://git.kernel.org/netdev/net-next/c/f71c549b26a3
  - [net-next,v4,2/3] selftests: drv-net: Factor out ksft C helpers
    (no matching commit)
  - [net-next,v4,3/3] selftests: drv-net: Test that NAPI ID is non-zero
    https://git.kernel.org/netdev/net-next/c/2593a0a1446a

You are awesome, thank you!
-- 
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