linux-kernel - [PATCH net-next v2 1/3] vsock/test: add timeout_usleep() to allow sleeping in timeout sections

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Message-ID: <20250514141927.159456-2-sgarzare@redhat.com>
Date: Wed, 14 May 2025 16:19:25 +0200
From: Stefano Garzarella <sgarzare@...hat.com>
To: netdev@...r.kernel.org
Cc: virtualization@...ts.linux.dev,
	Stefano Garzarella <sgarzare@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH net-next v2 1/3] vsock/test: add timeout_usleep() to allow sleeping in timeout sections

From: Stefano Garzarella <sgarzare@...hat.com>

The timeout API uses signals, so we have documented not to use sleep(),
but we can use nanosleep(2) since POSIX.1 explicitly specifies that it
does not interact with signals.

Let's provide timeout_usleep() for that.

Signed-off-by: Stefano Garzarella <sgarzare@...hat.com>
---
 tools/testing/vsock/timeout.h |  1 +
 tools/testing/vsock/timeout.c | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/tools/testing/vsock/timeout.h b/tools/testing/vsock/timeout.h
index ecb7c840e65a..1c3fcad87a49 100644
--- a/tools/testing/vsock/timeout.h
+++ b/tools/testing/vsock/timeout.h
@@ -11,5 +11,6 @@ void sigalrm(int signo);
 void timeout_begin(unsigned int seconds);
 void timeout_check(const char *operation);
 void timeout_end(void);
+int timeout_usleep(useconds_t usec);
 
 #endif /* TIMEOUT_H */
diff --git a/tools/testing/vsock/timeout.c b/tools/testing/vsock/timeout.c
index 44aee49b6cee..1453d38e08bb 100644
--- a/tools/testing/vsock/timeout.c
+++ b/tools/testing/vsock/timeout.c
@@ -21,6 +21,7 @@
 #include <stdbool.h>
 #include <unistd.h>
 #include <stdio.h>
+#include <time.h>
 #include "timeout.h"
 
 static volatile bool timeout;
@@ -28,6 +29,8 @@ static volatile bool timeout;
 /* SIGALRM handler function.  Do not use sleep(2), alarm(2), or
  * setitimer(2) while using this API - they may interfere with each
  * other.
+ *
+ * If you need to sleep, please use timeout_sleep() provided by this API.
  */
 void sigalrm(int signo)
 {
@@ -58,3 +61,18 @@ void timeout_end(void)
 	alarm(0);
 	timeout = false;
 }
+
+/* Sleep in a timeout section.
+ *
+ * nanosleep(2) can be used with this API since POSIX.1 explicitly
+ * specifies that it does not interact with signals.
+ */
+int timeout_usleep(useconds_t usec)
+{
+	struct timespec ts = {
+		.tv_sec = usec / 1000000,
+		.tv_nsec = (usec % 1000000) * 1000,
+	};
+
+	return nanosleep(&ts, NULL);
+}
-- 
2.49.0