From: Bobby Eshleman <bobbyeshleman@meta.com>

Add test case for autorelease.

The test case is the same as the RX test, but enables autorelease.  The
original RX test is changed to use the -a 0 flag to disable autorelease.

TAP version 13
1..4
ok 1 devmem.check_rx
ok 2 devmem.check_rx_autorelease
ok 3 devmem.check_tx
ok 4 devmem.check_tx_chunks

Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
---
Changes in v8:
- removed stale/missing tests

Changes in v7:
- use autorelease netlink
- remove sockopt tests
---
 tools/testing/selftests/drivers/net/hw/devmem.py  | 21 +++++++++++++++++++--
 tools/testing/selftests/drivers/net/hw/ncdevmem.c | 19 +++++++++++++------
 2 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/tools/testing/selftests/drivers/net/hw/devmem.py b/tools/testing/selftests/drivers/net/hw/devmem.py
index 45c2d49d55b6..dbe696a445bd 100755
--- a/tools/testing/selftests/drivers/net/hw/devmem.py
+++ b/tools/testing/selftests/drivers/net/hw/devmem.py
@@ -25,7 +25,24 @@ def check_rx(cfg) -> None:
 
     port = rand_port()
     socat = f"socat -u - TCP{cfg.addr_ipver}:{cfg.baddr}:{port},bind={cfg.remote_baddr}:{port}"
-    listen_cmd = f"{cfg.bin_local} -l -f {cfg.ifname} -s {cfg.addr} -p {port} -c {cfg.remote_addr} -v 7"
+    listen_cmd = f"{cfg.bin_local} -l -f {cfg.ifname} -s {cfg.addr} -p {port} -c {cfg.remote_addr} -v 7 -a 0"
+
+    with bkg(listen_cmd, exit_wait=True) as ncdevmem:
+        wait_port_listen(port)
+        cmd(f"yes $(echo -e \x01\x02\x03\x04\x05\x06) | \
+            head -c 1K | {socat}", host=cfg.remote, shell=True)
+
+    ksft_eq(ncdevmem.ret, 0)
+
+
+@ksft_disruptive
+def check_rx_autorelease(cfg) -> None:
+    require_devmem(cfg)
+
+    port = rand_port()
+    socat = f"socat -u - TCP{cfg.addr_ipver}:{cfg.baddr}:{port},bind={cfg.remote_baddr}:{port}"
+    listen_cmd = f"{cfg.bin_local} -l -f {cfg.ifname} -s {cfg.addr} -p {port} \
+                  -c {cfg.remote_addr} -v 7 -a 1"
 
     with bkg(listen_cmd, exit_wait=True) as ncdevmem:
         wait_port_listen(port)
@@ -68,7 +85,7 @@ def main() -> None:
         cfg.bin_local = path.abspath(path.dirname(__file__) + "/ncdevmem")
         cfg.bin_remote = cfg.remote.deploy(cfg.bin_local)
 
-        ksft_run([check_rx, check_tx, check_tx_chunks],
+        ksft_run([check_rx, check_rx_autorelease, check_tx, check_tx_chunks],
                  args=(cfg, ))
     ksft_exit()
 
diff --git a/tools/testing/selftests/drivers/net/hw/ncdevmem.c b/tools/testing/selftests/drivers/net/hw/ncdevmem.c
index 3288ed04ce08..406f1771d9ec 100644
--- a/tools/testing/selftests/drivers/net/hw/ncdevmem.c
+++ b/tools/testing/selftests/drivers/net/hw/ncdevmem.c
@@ -92,6 +92,7 @@ static char *port;
 static size_t do_validation;
 static int start_queue = -1;
 static int num_queues = -1;
+static int devmem_autorelease;
 static char *ifname;
 static unsigned int ifindex;
 static unsigned int dmabuf_id;
@@ -679,7 +680,8 @@ static int configure_flow_steering(struct sockaddr_in6 *server_sin)
 
 static int bind_rx_queue(unsigned int ifindex, unsigned int dmabuf_fd,
 			 struct netdev_queue_id *queues,
-			 unsigned int n_queue_index, struct ynl_sock **ys)
+			 unsigned int n_queue_index, struct ynl_sock **ys,
+			 int autorelease)
 {
 	struct netdev_bind_rx_req *req = NULL;
 	struct netdev_bind_rx_rsp *rsp = NULL;
@@ -695,6 +697,7 @@ static int bind_rx_queue(unsigned int ifindex, unsigned int dmabuf_fd,
 	req = netdev_bind_rx_req_alloc();
 	netdev_bind_rx_req_set_ifindex(req, ifindex);
 	netdev_bind_rx_req_set_fd(req, dmabuf_fd);
+	netdev_bind_rx_req_set_autorelease(req, autorelease);
 	__netdev_bind_rx_req_set_queues(req, queues, n_queue_index);
 
 	rsp = netdev_bind_rx(*ys, req);
@@ -872,7 +875,8 @@ static int do_server(struct memory_buffer *mem)
 		goto err_reset_rss;
 	}
 
-	if (bind_rx_queue(ifindex, mem->fd, create_queues(), num_queues, &ys)) {
+	if (bind_rx_queue(ifindex, mem->fd, create_queues(), num_queues, &ys,
+			  devmem_autorelease)) {
 		pr_err("Failed to bind");
 		goto err_reset_flow_steering;
 	}
@@ -1092,7 +1096,7 @@ int run_devmem_tests(void)
 		goto err_reset_headersplit;
 	}
 
-	if (!bind_rx_queue(ifindex, mem->fd, queues, num_queues, &ys)) {
+	if (!bind_rx_queue(ifindex, mem->fd, queues, num_queues, &ys, 0)) {
 		pr_err("Binding empty queues array should have failed");
 		goto err_unbind;
 	}
@@ -1108,7 +1112,7 @@ int run_devmem_tests(void)
 		goto err_reset_headersplit;
 	}
 
-	if (!bind_rx_queue(ifindex, mem->fd, queues, num_queues, &ys)) {
+	if (!bind_rx_queue(ifindex, mem->fd, queues, num_queues, &ys, 0)) {
 		pr_err("Configure dmabuf with header split off should have failed");
 		goto err_unbind;
 	}
@@ -1124,7 +1128,7 @@ int run_devmem_tests(void)
 		goto err_reset_headersplit;
 	}
 
-	if (bind_rx_queue(ifindex, mem->fd, queues, num_queues, &ys)) {
+	if (bind_rx_queue(ifindex, mem->fd, queues, num_queues, &ys, 0)) {
 		pr_err("Failed to bind");
 		goto err_reset_headersplit;
 	}
@@ -1397,7 +1401,7 @@ int main(int argc, char *argv[])
 	int is_server = 0, opt;
 	int ret, err = 1;
 
-	while ((opt = getopt(argc, argv, "ls:c:p:v:q:t:f:z:")) != -1) {
+	while ((opt = getopt(argc, argv, "ls:c:p:v:q:t:f:z:a:")) != -1) {
 		switch (opt) {
 		case 'l':
 			is_server = 1;
@@ -1426,6 +1430,9 @@ int main(int argc, char *argv[])
 		case 'z':
 			max_chunk = atoi(optarg);
 			break;
+		case 'a':
+			devmem_autorelease = atoi(optarg);
+			break;
 		case '?':
 			fprintf(stderr, "unknown option: %c\n", optopt);
 			break;

-- 
2.47.3

On Fri, Jan 9, 2026 at 6:19 PM Bobby Eshleman <bobbyeshleman@gmail.com> wrote:
>
> From: Bobby Eshleman <bobbyeshleman@meta.com>
>
> Add test case for autorelease.
>
> The test case is the same as the RX test, but enables autorelease.  The
> original RX test is changed to use the -a 0 flag to disable autorelease.
>
> TAP version 13
> 1..4
> ok 1 devmem.check_rx
> ok 2 devmem.check_rx_autorelease
> ok 3 devmem.check_tx
> ok 4 devmem.check_tx_chunks
>
> Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>

Can you add a test for the problematic/weird scenario I comment on patch 3?

1. User does bind (autorelease on or off)
2. Data is received.
3. User does unbind.
4. User calls recevmsg()
5. User calls dontneed on the frags obtained in 4.

This should work with autorelease=on or off, or at least emit a clean
error message (kernel must not splat).

I realize a made a suggestion in patch 3 that may make this hard to
test (i.e. put the kernel in autorelease on/off mode for the boot
session on the first unbind). If we can add a test while making that
simplification great, if not, lets not make the simplification I
guess.

On Sun, Jan 11, 2026 at 11:16:37AM -0800, Mina Almasry wrote:
> On Fri, Jan 9, 2026 at 6:19 PM Bobby Eshleman <bobbyeshleman@gmail.com> wrote:
> >
> > From: Bobby Eshleman <bobbyeshleman@meta.com>
> >
> > Add test case for autorelease.
> >
> > The test case is the same as the RX test, but enables autorelease.  The
> > original RX test is changed to use the -a 0 flag to disable autorelease.
> >
> > TAP version 13
> > 1..4
> > ok 1 devmem.check_rx
> > ok 2 devmem.check_rx_autorelease
> > ok 3 devmem.check_tx
> > ok 4 devmem.check_tx_chunks
> >
> > Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
> 
> Can you add a test for the problematic/weird scenario I comment on patch 3?
> 
> 1. User does bind (autorelease on or off)
> 2. Data is received.
> 3. User does unbind.
> 4. User calls recevmsg()
> 5. User calls dontneed on the frags obtained in 4.
> 
> This should work with autorelease=on or off, or at least emit a clean
> error message (kernel must not splat).

IIUC, this looks something like (psuedo-code):

ncdevmem.c:

do_server(...) {

	client_fd = accept(...);

	if (check_premature_unbind) {
		/* wait for data but don't recvmsg yet */
		epoll(client_fd, ...);

		/* unbind */
		ynl_sock_destroy(ys);
		
		while (1) {
			ret = recvmsg(client_fd, &msg, MSG_SOCK_DEVMEM);
			/* check ret */

			ret = setsockopt(client_fd, SOL_SOCKET, SO_DEVMEM_DONTNEED, ...)
			/* check ret */
		}
	} else { ... }
}

... then devmem.py checks dmesg?

> 
> I realize a made a suggestion in patch 3 that may make this hard to
> test (i.e. put the kernel in autorelease on/off mode for the boot
> session on the first unbind). If we can add a test while making that
> simplification great, if not, lets not make the simplification I
> guess.

I think we can do both the simplification and this test, but in general
we would have to skip any test when rx bind fails due to the test's new
mode not matching. Not sure if that is desired.

I tend to like the simplification because I really dislike having to
track the RX binding count, but I'm not sure if there is a good way to
do that with making our tests locked into a single mode.

Maybe a debugfs reset option that rejects when rx_bindings_count is
non-zero? That way we can remove all the program logic around
rx_bindings_count and make it's inc/dec wrapper functions no-ops in
production (CONFIG_DEBUG_NET_DEVMEM=n), but still test both modes?


The handler would look something like (approx.):

#ifdef CONFIG_DEBUG_NET_DEVMEM
static ssize_t devmem_reset_write(struct file *file, const char __user *buf,
				  size_t count, loff_t *ppos)
{
	int ret = count;

	mutex_lock(&devmem_ar_lock);

	if (net_devmem_rx_bindings_count_read() != 0) {
		ret = -EBUSY;
		goto unlock;
	}

	/* enable setting the key again via bind_rx) */
	tcp_devmem_ar_locked = false;

	static_branch_disable(&tcp_devmem_ar_key);

unlock:
	mutex_unlock(&devmem_ar_lock);
	return ret;
}
[...]
#endif


... but I couldn't find a good precedent for this in the current
selftests. 

Best,
Bobby