svn commit: r368057 - stable/12/sys/kern

[Mark Johnston]

Author: markj
Date: Thu Nov 26 14:57:30 2020
New Revision: 368057
URL: https://svnweb.freebsd.org/changeset/base/368057

Log:
  MFC r367849:
  callout(9): Fix a race between CPU migration and callout_drain()

Modified:
  stable/12/sys/kern/kern_timeout.c
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/sys/kern/kern_timeout.c
==============================================================================
--- stable/12/sys/kern/kern_timeout.c	Thu Nov 26 14:42:16 2020	(r368056)
+++ stable/12/sys/kern/kern_timeout.c	Thu Nov 26 14:57:30 2020	(r368057)
@@ -1274,7 +1274,7 @@ again:
 			 * just wait for the current invocation to
 			 * finish.
 			 */
-			while (cc_exec_curr(cc, direct) == c) {
+			if (cc_exec_curr(cc, direct) == c) {
 				/*
 				 * Use direct calls to sleepqueue interface
 				 * instead of cv/msleep in order to avoid
@@ -1322,7 +1322,7 @@ again:
 
 				/* Reacquire locks previously released. */
 				PICKUP_GIANT();
-				CC_LOCK(cc);
+				goto again;
 			}
 			c->c_flags &= ~CALLOUT_ACTIVE;
 		} else if (use_lock &&