[PATCH 1/2] libcamera: v4l2_device: Retry ::ioctl on EINTR

[Umang Jain]

V4L userspace API documentation clearly mentions the handling of
EINTR on ioctl(). Align with the xioctl() reference provided in [1].

Retry the ::ioctl() if failed with errno == EINTR. Use a do..while{}
to check the return value of ::ioctl() and errno value. If the return
value is found to be -1, and errno is set with EINTR, the ioctl() call
should be retried.

[1]: https://docs.kernel.org/userspace-api/media/v4l/capture.c.html

Signed-off-by: Umang Jain <umang.jain at ideasonboard.com>
---
 src/libcamera/v4l2_device.cpp | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
index 4a2048cf..2e92db0f 100644
--- a/src/libcamera/v4l2_device.cpp
+++ b/src/libcamera/v4l2_device.cpp
@@ -454,11 +454,17 @@ int V4L2Device::setFrameStartEnabled(bool enable)
  */
 int V4L2Device::ioctl(unsigned long request, void *argp)
 {
+	int ret;
+
+	do {
+		ret = ::ioctl(fd_.get(), request, argp);
+	} while (ret == -1 && errno == EINTR);
+
 	/*
 	 * Printing out an error message is usually better performed
 	 * in the caller, which can provide more context.
 	 */
-	if (::ioctl(fd_.get(), request, argp) < 0)
+	if (ret < 0)
 		return -errno;
 
 	return 0;
-- 
2.45.2