[PATCH] udevsettle should read udev not kernel seqnum first

[Pozsar Balazs <pozsy@uhulinux.hu>]

Hi all,

I think that the order of reading the kernel and udev seqnum files 
should be: first udev, then kernel, because with the current code 
there's a chance of exiting too early, for example in the following 
scenario:
 1. kernel seqnum is X, udevsettle reads it
 2. udev finishes processing the event X, which generates new events
    (for example a modprobe), udev seqnum becomes X
 3. udevsettle reads the udev seqnum which is X now, so it exits
 4. at least another event comes which should have been waited for

Attached patch changes the order to first read the udev seqnum.


diff -Naurd a/udevsettle.c b/udevsettle.c
--- a/udevsettle.c	2006-04-15 19:32:38.000000000 +0200
+++ b/udevsettle.c	2006-04-25 21:40:57.000000000 +0200
@@ -111,9 +111,9 @@
 			goto exit;
 		}
 
-		/* read current kernel seqnum */
-		strlcpy(filename, sysfs_path, sizeof(filename));
-		strlcat(filename, "/kernel/uevent_seqnum", sizeof(filename));
+		/* read current udev seqnum */
+		strlcpy(filename, udev_root, sizeof(filename));
+		strlcat(filename, "/" EVENT_SEQNUM, sizeof(filename));
 		fd = open(filename, O_RDONLY);
 		if (fd < 0)
 			goto exit;
@@ -122,12 +122,12 @@
 		if (len <= 0)
 			goto exit;
 		seqnum[len] = '\0';
-		seq_kernel = strtoull(seqnum, NULL, 10);
-		info("kernel seqnum = %llu", seq_kernel);
+		seq_udev = strtoull(seqnum, NULL, 10);
+		info("udev seqnum = %llu", seq_udev);
 
-		/* read current udev seqnum */
-		strlcpy(filename, udev_root, sizeof(filename));
-		strlcat(filename, "/" EVENT_SEQNUM, sizeof(filename));
+		/* read current kernel seqnum */
+		strlcpy(filename, sysfs_path, sizeof(filename));
+		strlcat(filename, "/kernel/uevent_seqnum", sizeof(filename));
 		fd = open(filename, O_RDONLY);
 		if (fd < 0)
 			goto exit;
@@ -136,8 +136,8 @@
 		if (len <= 0)
 			goto exit;
 		seqnum[len] = '\0';
-		seq_udev = strtoull(seqnum, NULL, 10);
-		info("udev seqnum = %llu", seq_udev);
+		seq_kernel = strtoull(seqnum, NULL, 10);
+		info("kernel seqnum = %llu", seq_kernel);
 
 		/* make sure all kernel events have arrived in the queue */
 		if (seq_udev >= seq_kernel) {


-- 
pozsy

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