[PATCH] improve event sequence serialization

We delay the execution of events if there is already an event running for
the same device, a parent or a child device. "add" events with a reference
to a physical device will also wait for the physical device to finish.

Here we fix the devpath comparison logic to return "busy" only if a complete
device names is matching. /block/sdaa will not longer block a /block/sda event.

diff --git a/udevd.c b/udevd.c
index c6642f4359b890d1cb63cdf75ddff4739df52fab..569458484010ac79be923a7fc99a5fb75049b83b 100644 (file)
--- a/udevd.c
+++ b/udevd.c
@@ -151,34 +151,51 @@ static void udev_run(struct hotplug_msg *msg)
        }
 }
 
-/* returns still running task for the same event sequence */
+static int compare_devpath(const char *running, const char *waiting)
+{
+       int i;
+
+       for (i = 0; i < DEVPATH_SIZE; i++) {
+               /* identical device event found */
+               if (running[i] == '\0' && waiting[i] == '\0')
+                       return 1;
+
+               /* parent device event found */
+               if (running[i] == '\0' && waiting[i] == '/')
+                       return 2;
+
+               /* child device event found */
+               if (running[i] == '/' && waiting[i] == '\0')
+                       return 3;
+
+               /* no matching event */
+               if (running[i] != waiting[i])
+                       break;
+       }
+
+       return 0;
+}
+
+/* returns still running task for the same device, its parent or its physical device */
 static struct hotplug_msg *running_with_devpath(struct hotplug_msg *msg)
 {
        struct hotplug_msg *loop_msg;
-       int i;
+
+       if (msg->devpath == NULL)
+               return NULL;
 
        list_for_each_entry(loop_msg, &running_list, list) {
-               if (loop_msg->devpath == NULL || msg->devpath == NULL)
+               if (loop_msg->devpath == NULL)
                        continue;
 
-               /* is a parent or child device event still running */
-               for (i = 0; i < DEVPATH_SIZE; i++) {
-                       if (loop_msg->devpath[i] == '\0' || msg->devpath[i] == '\0')
-                               return loop_msg;
+               /* return running parent/child device event */
+               if (compare_devpath(loop_msg->devpath, msg->devpath) != 0)
+                       return loop_msg;
 
-                       if (loop_msg->devpath[i] != msg->devpath[i])
-                               break;
-               }
-
-               /* is the physical device event still running on an add sequence */
+               /* return running physical device event */
                if (msg->physdevpath && msg->action && strcmp(msg->action, "add") == 0)
-                       for (i = 0; i < DEVPATH_SIZE; i++) {
-                               if (loop_msg->devpath[i] == '\0' || msg->physdevpath[i] == '\0')
-                                       return loop_msg;
-
-                               if (loop_msg->devpath[i] != msg->physdevpath[i])
-                                       break;
-                       }
+                       if (compare_devpath(loop_msg->devpath, msg->physdevpath) != 0)
+                               return loop_msg;
        }
 
        return NULL;