nodedev: udev: Introduce udevEventMonitorSanityCheck helper function

We need to perform a sanity check on the udev monitor before every
use so that we know nothing has changed in the meantime. The reason for
moving the code to a separate helper is to enhance readability and shift
the focus on the important stuff within the udevEventHandleCallback
handler.

Signed-off-by: Erik Skultety <eskultet@redhat.com>

diff --git a/src/node_device/node_device_udev.c b/src/node_device/node_device_udev.c
index 8ea5d1e626e0887e82b08eed7a2361fb2f57fdb2..8314b3834e2f7f2b90f3c937070b830dfd92a5d5 100644 (file)
--- a/src/node_device/node_device_udev.c
+++ b/src/node_device/node_device_udev.c
@@ -1618,24 +1618,20 @@ udevHandleOneDevice(struct udev_device *device)
 }
 
 
-static void
-udevEventHandleCallback(int watch ATTRIBUTE_UNUSED,
-                        int fd,
-                        int events ATTRIBUTE_UNUSED,
-                        void *data ATTRIBUTE_UNUSED)
+static bool
+udevEventMonitorSanityCheck(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;
+    int rc = -1;
 
-    udev_fd = udev_monitor_get_fd(udev_monitor);
-    if (fd != udev_fd) {
+    rc = udev_monitor_get_fd(udev_monitor);
+    if (fd != rc) {
         udevPrivate *priv = driver->privateData;
 
         virReportError(VIR_ERR_INTERNAL_ERROR,
                        _("File descriptor returned by udev %d does not "
                          "match node device file descriptor %d"),
-                       fd, udev_fd);
+                       fd, rc);
 
         /* this is a non-recoverable error, let's remove the handle, so that we
          * don't get in here again because of some spurious behaviour and report
@@ -1644,21 +1640,36 @@ 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 (!udevEventMonitorSanityCheck(udev_monitor, fd))
+        return;
+
     device = udev_monitor_receive_device(udev_monitor);
     if (device == NULL) {
         virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
                        _("udev_monitor_receive_device returned NULL"));
-        goto cleanup;
+        return;
     }
 
     udevHandleOneDevice(device);
-
- cleanup:
     udev_device_unref(device);
-    return;
 }