[libvirt] [PATCH v4 1/7] nodedev: Introduce udevEventCheckMonitorFD helper function

[Erik Skultety]

We need to perform some sanity checks on the udev monitor before every
use so that we know nothing changed in the meantime. The reason for
moving the code to a separate function is to be able to perform the same
check from a worker thread that will replace the udevEventHandleCallback
in terms of poking udev for device events.

Signed-off-by: Erik Skultety <eskultet at redhat.com>
---
 src/node_device/node_device_udev.c | 40 +++++++++++++++++++++++++-------------
 1 file changed, 27 insertions(+), 13 deletions(-)

diff --git a/src/node_device/node_device_udev.c b/src/node_device/node_device_udev.c
index f4177455c..fe21ad7df 100644
--- a/src/node_device/node_device_udev.c
+++ b/src/node_device/node_device_udev.c
@@ -1615,14 +1615,10 @@ udevHandleOneDevice(struct udev_device *device)
 }
 
 
-static void
-udevEventHandleCallback(int watch ATTRIBUTE_UNUSED,
-                        int fd,
-                        int events ATTRIBUTE_UNUSED,
-                        void *data ATTRIBUTE_UNUSED)
+static bool
+udevEventCheckMonitorFD(struct udev_monitor *udev_monitor,
+                        int fd)
 {
-    struct udev_device *device = NULL;
-    struct udev_monitor *udev_monitor = DRV_STATE_UDEV_MONITOR(driver);
     int udev_fd = -1;
 
     udev_fd = udev_monitor_get_fd(udev_monitor);
@@ -1641,21 +1637,39 @@ udevEventHandleCallback(int watch ATTRIBUTE_UNUSED,
         virEventRemoveHandle(priv->watch);
         priv->watch = -1;
 
-        goto cleanup;
+        return false;
+    }
+
+    return true;
+}
+
+
+static void
+udevEventHandleCallback(int watch ATTRIBUTE_UNUSED,
+                        int fd,
+                        int events ATTRIBUTE_UNUSED,
+                        void *data ATTRIBUTE_UNUSED)
+{
+    struct udev_device *device = NULL;
+    struct udev_monitor *udev_monitor = NULL;
+
+    udev_monitor = DRV_STATE_UDEV_MONITOR(driver);
+
+    if (!udevEventCheckMonitorFD(udev_monitor, fd)) {
+        nodeDeviceUnlock();
+        return;
     }
 
     device = udev_monitor_receive_device(udev_monitor);
-    if (device == NULL) {
+
+    if (!device) {
         virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
                        _("udev_monitor_receive_device returned NULL"));
-        goto cleanup;
+        return;
     }
 
     udevHandleOneDevice(device);
-
- cleanup:
     udev_device_unref(device);
-    return;
 }
 
 
-- 
2.13.5