[PATCH] udev_monitor_receive_device() will block when hotplug monitor

[jimqu]

udev_monitor_receive_device() will block and wait for the event of udev
use select() to ensure that this will not block.

Change-Id: I4e8f4629580222e94f55a4c03070741bf5f4024c
Signed-off-by: JimQu <Jim.Qu at amd.com>
---
 src/drmmode_display.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/src/drmmode_display.c b/src/drmmode_display.c
index 79c9390..a5b4345 100644
--- a/src/drmmode_display.c
+++ b/src/drmmode_display.c
@@ -2528,10 +2528,26 @@ static void drmmode_handle_uevents(int fd, void *closure)
 	ScrnInfoPtr scrn = drmmode->scrn;
 	struct udev_device *dev;
 	Bool received = FALSE;
+	struct timeval tv;
+	fd_set readfd;
+	int ret;
+
+	FD_ZERO(&readfd);
+	FD_SET(fd, &readfd);
+	tv.tv_sec = 0;
+	tv.tv_usec = 0;
 
-	while ((dev = udev_monitor_receive_device(drmmode->uevent_monitor))) {
-		udev_device_unref(dev);
-		received = TRUE;
+	while (1) {
+		ret = select(fd + 1, &readfd, NULL, NULL, &tv);
+		/* Check if our file descriptor has received data. */
+		if (!(ret > 0 && FD_ISSET(fd, &readfd)))
+			break;
+		/* Make the call to receive device. select() ensured that this will not be blocked. */
+		dev = udev_monitor_receive_device(drmmode->uevent_monitor);
+		if (dev) {
+			udev_device_unref(dev);
+			received = TRUE;
+		}
 	}
 
 	if (received)
-- 
1.9.1