[dm-devel] patch for log_enqueue in multipath-tools-0.4.4-pre11

[Benjamin Marzinski <bmarzins redhat com>]

It looks to me like log_enqueue can accidentally mess up its la->tail ptr,
if it runs out of space for the new message.

If the la->head is just past la->start, and la->tail is just before la->end,
la->tail will get updated to be la->start, because there is no room at the
end of the buffer for the message.  Then when it realizes that there is no
room at the start of the buffer, la->tail will be updated to la->start - fwd
And the next message will be written before the buffer.

This patch fixes that.

-Ben
Ben Marzinski
bmarzins redhat com
(612) 638-0517

diff -urN multipath-tools-0.4.4-pre11/multipathd/log.c multipath-tools-0.4.4-log-fixed/multipathd/log.c
--- multipath-tools-0.4.4-pre11/multipathd/log.c	2005-03-31 03:25:06.000000000 -0600
+++ multipath-tools-0.4.4-log-fixed/multipathd/log.c	2005-04-11 14:27:41.000000000 -0500
@@ -119,7 +119,7 @@
 		logdbg(stderr, "enqueue: log area overrun, drop msg\n");
 
 		if (!la->empty)
-			la->tail -= fwd;
+			la->tail = lastmsg;
 
 		return 1;
 	}