linux-kernel - Re: [PATCH net-next v3 2/3] test/vsock: Add retry mechanism to ioctl wrapper

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Message-ID: <uqpldq5hhpmmgayozfh62wiloggk7rsih6n5lzby75cgxvhbiq@fspi6ik7lbp6>
Date: Tue, 17 Jun 2025 17:10:59 +0200
From: Stefano Garzarella <sgarzare@...hat.com>
To: Xuewei Niu <niuxuewei97@...il.com>
Cc: mst@...hat.com, pabeni@...hat.com, jasowang@...hat.com, 
	xuanzhuo@...ux.alibaba.com, davem@...emloft.net, netdev@...r.kernel.org, stefanha@...hat.com, 
	leonardi@...hat.com, virtualization@...ts.linux.dev, kvm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, fupan.lfp@...group.com, Xuewei Niu <niuxuewei.nxw@...group.com>
Subject: Re: [PATCH net-next v3 2/3] test/vsock: Add retry mechanism to ioctl
 wrapper

On Tue, Jun 17, 2025 at 12:53:45PM +0800, Xuewei Niu wrote:
>Wrap the ioctl in `ioctl_int()`, which takes a pointer to the actual
>int value and an expected int value. The function will not return until
>either the ioctl returns the expected value or a timeout occurs, thus
>avoiding immediate failure.
>
>Signed-off-by: Xuewei Niu <niuxuewei.nxw@...group.com>
>---
> tools/testing/vsock/util.c | 37 ++++++++++++++++++++++++++++---------
> tools/testing/vsock/util.h |  1 +
> 2 files changed, 29 insertions(+), 9 deletions(-)
>
>diff --git a/tools/testing/vsock/util.c b/tools/testing/vsock/util.c
>index 0c7e9cbcbc85..ecfbe52efca2 100644
>--- a/tools/testing/vsock/util.c
>+++ b/tools/testing/vsock/util.c
>@@ -16,6 +16,7 @@
> #include <unistd.h>
> #include <assert.h>
> #include <sys/epoll.h>
>+#include <sys/ioctl.h>
> #include <sys/mman.h>
> #include <linux/sockios.h>
>
>@@ -97,28 +98,46 @@ void vsock_wait_remote_close(int fd)
> 	close(epollfd);
> }
>
>-/* Wait until transport reports no data left to be sent.
>- * Return false if transport does not implement the unsent_bytes() callback.
>+/* Wait until ioctl gives an expected int value.
>+ * Return a negative value if the op is not supported.
>  */
>-bool vsock_wait_sent(int fd)
>+int ioctl_int(int fd, unsigned long op, int *actual, int expected)
> {
>-	int ret, sock_bytes_unsent;
>+	int ret;
>+	char name[32];
>+
>+	if (!actual) {
>+		fprintf(stderr, "%s requires a non-null pointer\n", __func__);
>+		exit(EXIT_FAILURE);
>+	}

I think we can skip this kind of validation in a test, it will crash 
anyway and we don't have in other places.

>+
>+	snprintf(name, sizeof(name), "ioctl(%lu)", op);
>
> 	timeout_begin(TIMEOUT);
> 	do {
>-		ret = ioctl(fd, SIOCOUTQ, &sock_bytes_unsent);
>+		ret = ioctl(fd, op, actual);
> 		if (ret < 0) {
> 			if (errno == EOPNOTSUPP)
> 				break;
>
>-			perror("ioctl(SIOCOUTQ)");
>+			perror(name);
> 			exit(EXIT_FAILURE);
> 		}
>-		timeout_check("SIOCOUTQ");
>-	} while (sock_bytes_unsent != 0);
>+		timeout_check(name);
>+	} while (*actual != expected);
> 	timeout_end();
>
>-	return !ret;
>+	return ret;
>+}
>+
>+/* Wait until transport reports no data left to be sent.
>+ * Return false if transport does not implement the unsent_bytes() callback.
>+ */
>+bool vsock_wait_sent(int fd)
>+{
>+	int sock_bytes_unsent;
>+
>+	return !(ioctl_int(fd, SIOCOUTQ, &sock_bytes_unsent, 0));
> }
>
> /* Create socket <type>, bind to <cid, port> and return the file descriptor. */
>diff --git a/tools/testing/vsock/util.h b/tools/testing/vsock/util.h
>index 5e2db67072d5..f3fe725cdeab 100644
>--- a/tools/testing/vsock/util.h
>+++ b/tools/testing/vsock/util.h
>@@ -54,6 +54,7 @@ int vsock_stream_listen(unsigned int cid, unsigned int port);
> int vsock_seqpacket_accept(unsigned int cid, unsigned int port,
> 			   struct sockaddr_vm *clientaddrp);
> void vsock_wait_remote_close(int fd);
>+int ioctl_int(int fd, unsigned long op, int *actual, int expected);

what about using vsock_* prefix?
nit: if not, please move after the vsock_* functions.

The rest LGTM!

Thanks,
Stefano

> bool vsock_wait_sent(int fd);
> void send_buf(int fd, const void *buf, size_t len, int flags,
> 	      ssize_t expected_ret);
>-- 
>2.34.1
>