Author: mjg
Date: Sat Dec 31 12:49:20 2016
New Revision: 310965
URL: https://svnweb.freebsd.org/changeset/base/310965
Log:
MFC r303921:
ktrace: do a lockless check on fork to see if tracing is enabled
This saves 2 lock acquisitions in the common case.
Modified:
stable/11/sys/kern/kern_ktrace.c
Directory Properties:
stable/11/ (props changed)
Modified: stable/11/sys/kern/kern_ktrace.c
==============================================================================
--- stable/11/sys/kern/kern_ktrace.c Sat Dec 31 12:47:41 2016
(r310964)
+++ stable/11/sys/kern/kern_ktrace.c Sat Dec 31 12:49:20 2016
(r310965)
@@ -572,9 +572,14 @@ void
ktrprocfork(struct proc *p1, struct proc *p2)
{
+ MPASS(p2->p_tracevp == NULL);
+ MPASS(p2->p_traceflag == 0);
+
+ if (p1->p_traceflag == 0)
+ return;
+
PROC_LOCK(p1);
mtx_lock(&ktrace_mtx);
- KASSERT(p2->p_tracevp == NULL, ("new process has a ktrace vnode"));
if (p1->p_traceflag & KTRFAC_INHERIT) {
p2->p_traceflag = p1->p_traceflag;
if ((p2->p_tracevp = p1->p_tracevp) != NULL) {
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