svn commit: r247419 - projects/calloutng/sys/kern

[Alexander Motin]

Author: mav
Date: Wed Feb 27 20:54:45 2013
New Revision: 247419
URL: http://svnweb.freebsd.org/changeset/base/247419

Log:
  Close the hypothetical race when new callout inserted into the callwheel
  bucket, that now executes its last callout in direct mode, and so dropped
  the lock, caching NULL as the next callout pointer.

Modified:
  projects/calloutng/sys/kern/kern_timeout.c

Modified: projects/calloutng/sys/kern/kern_timeout.c
==============================================================================
--- projects/calloutng/sys/kern/kern_timeout.c	Wed Feb 27 20:20:21 2013	(r247418)
+++ projects/calloutng/sys/kern/kern_timeout.c	Wed Feb 27 20:54:45 2013	(r247419)
@@ -489,7 +489,6 @@ next:
 		 * Stop if we looked far enough into the future.
 		 */
 	} while (firstb <= lastb);
-	cc->cc_exec_next_dir = NULL;
 	cc->cc_firstevent = last;
 #ifndef NO_EVENTTIMERS
 	cpu_new_callout(curcpu, last, first);
@@ -555,6 +554,8 @@ callout_cc_add(struct callout *c, struct
 	    c, (int)(c->c_precision >> 32), 
 	    (u_int)(c->c_precision & 0xffffffff));
 	TAILQ_INSERT_TAIL(&cc->cc_callwheel[bucket], c, c_links.tqe);
+	if (cc->cc_exec_next_dir == NULL)
+		cc->cc_exec_next_dir = c;
 #ifndef NO_EVENTTIMERS
 	/*
 	 * Inform the eventtimers(4) subsystem there's a new callout