linux-kernel - [PATCH net-next 2/2] vsock/test: Expand linger test to ensure close() does not misbehave

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Message-Id: <20250407-vsock-linger-v1-2-1458038e3492@rbox.co>
Date: Mon, 07 Apr 2025 20:41:44 +0200
From: Michal Luczaj <mhal@...x.co>
To: Stefano Garzarella <sgarzare@...hat.com>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
 Simon Horman <horms@...nel.org>, "Michael S. Tsirkin" <mst@...hat.com>, 
 Jason Wang <jasowang@...hat.com>, Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, 
 Eugenio Pérez <eperezma@...hat.com>, 
 Stefan Hajnoczi <stefanha@...hat.com>
Cc: virtualization@...ts.linux.dev, netdev@...r.kernel.org, 
 linux-kernel@...r.kernel.org, kvm@...r.kernel.org, 
 Michal Luczaj <mhal@...x.co>
Subject: [PATCH net-next 2/2] vsock/test: Expand linger test to ensure
 close() does not misbehave

Add a check to alert on close() lingering when it should not.

Signed-off-by: Michal Luczaj <mhal@...x.co>
---
 tools/testing/vsock/vsock_test.c | 30 +++++++++++++++++++++++++++---
 1 file changed, 27 insertions(+), 3 deletions(-)

diff --git a/tools/testing/vsock/vsock_test.c b/tools/testing/vsock/vsock_test.c
index d0f6d253ac72d08a957cb81a3c38fcc72bec5a53..82d0bc20dfa75041f04eada1b4310be2f7c3a0c1 100644
--- a/tools/testing/vsock/vsock_test.c
+++ b/tools/testing/vsock/vsock_test.c
@@ -1788,13 +1788,16 @@ static void test_stream_connect_retry_server(const struct test_opts *opts)
 	close(fd);
 }

+#define	LINGER_TIMEOUT	1	/* seconds */
+
 static void test_stream_linger_client(const struct test_opts *opts)
 {
 	struct linger optval = {
 		.l_onoff = 1,
-		.l_linger = 1
+		.l_linger = LINGER_TIMEOUT
 	};
-	int fd;
+	int bytes_unsent, fd;
+	time_t ts;

 	fd = vsock_stream_connect(opts->peer_cid, opts->peer_port);
 	if (fd < 0) {
@@ -1807,7 +1810,28 @@ static void test_stream_linger_client(const struct test_opts *opts)
 		exit(EXIT_FAILURE);
 	}

+	/* Byte left unread to expose any incorrect behaviour. */
+	send_byte(fd, 1, 0);
+
+	/* Reuse LINGER_TIMEOUT to wait for bytes_unsent == 0. */
+	timeout_begin(LINGER_TIMEOUT);
+	do {
+		if (ioctl(fd, SIOCOUTQ, &bytes_unsent) < 0) {
+			perror("ioctl(SIOCOUTQ)");
+			exit(EXIT_FAILURE);
+		}
+		timeout_check("ioctl(SIOCOUTQ) == 0");
+	} while (bytes_unsent != 0);
+	timeout_end();
+
+	ts = current_nsec();
 	close(fd);
+	if ((current_nsec() - ts) / NSEC_PER_SEC > 0) {
+		fprintf(stderr, "Unexpected lingering on close()\n");
+		exit(EXIT_FAILURE);
+	}
+
+	control_writeln("DONE");
 }

 static void test_stream_linger_server(const struct test_opts *opts)
@@ -1820,7 +1844,7 @@ static void test_stream_linger_server(const struct test_opts *opts)
 		exit(EXIT_FAILURE);
 	}

-	vsock_wait_remote_close(fd);
+	control_expectln("DONE");
 	close(fd);
 }

-- 
2.49.0