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From: Bryan Drewery <bdrewery@FreeBSD.org>
Date: Wed, 26 Aug 2015 03:37:18 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
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Subject: svn commit: r287153 - head/sys/dev/filemon
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Author: bdrewery
Date: Wed Aug 26 03:37:18 2015
New Revision: 287153
URL: https://svnweb.freebsd.org/changeset/base/287153

Log:
  Avoid taking proctree_lock and searching parents in wrappers if not needed.
  
  This should help the case where filemon is loaded but not in use.
  
  Sponsored by:	EMC / Isilon Storage Division
  MFC after:	2 weeks

Modified:
  head/sys/dev/filemon/filemon_wrapper.c

Modified: head/sys/dev/filemon/filemon_wrapper.c
==============================================================================
--- head/sys/dev/filemon/filemon_wrapper.c	Wed Aug 26 03:33:34 2015	(r287152)
+++ head/sys/dev/filemon/filemon_wrapper.c	Wed Aug 26 03:37:18 2015	(r287153)
@@ -88,6 +88,10 @@ filemon_pid_check(struct proc *p)
 	struct filemon *filemon;
 
 	filemon_lock_read();
+	if (TAILQ_EMPTY(&filemons_inuse)) {
+		filemon_unlock_read();
+		return (NULL);
+	}
 	sx_slock(&proctree_lock);
 	while (p != initproc) {
 		TAILQ_FOREACH(filemon, &filemons_inuse, link) {