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

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Message-Id: <20250617152348.1346298-1-niuxuewei.nxw@antgroup.com>
Date: Tue, 17 Jun 2025 23:23:48 +0800
From: Xuewei Niu <niuxuewei97@...il.com>
To: sgarzare@...hat.com
Cc: davem@...emloft.net,
	fupan.lfp@...group.com,
	jasowang@...hat.com,
	kvm@...r.kernel.org,
	leonardi@...hat.com,
	linux-kernel@...r.kernel.org,
	mst@...hat.com,
	netdev@...r.kernel.org,
	niuxuewei.nxw@...group.com,
	niuxuewei97@...il.com,
	pabeni@...hat.com,
	stefanha@...hat.com,
	virtualization@...ts.linux.dev,
	xuanzhuo@...ux.alibaba.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.

Will do.

> >+	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.

My first thought was that `ioctl_int()` doesn't take any arguments related
to vsock (e.g. cid).

I am fine with the prefix, and will add it back.

Thanks,
Xuewei

> 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
> >