From 1715f07da3f607d7a1426227556178a9d5c7b5f5 Mon Sep 17 00:00:00 2001
From: John Baldwin <jhb@FreeBSD.org>
Date: Mon, 25 Jun 2001 23:09:31 +0000
Subject: [PATCH] - Replace the unused KTR_IDLELOOP trace class with a new
 KTR_WITNESS trace   class to trace witness events. - Make the ktr_cpu field
 of ktr_entry be a standard field rather than one   present only in the
 KTR_EXTEND case. - Move the default definition of KTR_ENTRIES from sys/ktr.h
 to   kern/kern_ktr.c.  It has not been needed in the header file since KTR  
 was un-inlined. - Minor include cleanup in kern/kern_ktr.c. - Fiddle with the
 ktr_cpumask in ktr_tracepoint() to disable KTR events   on the current CPU
 while we are processing an event. - Set the current CPU inside of the
 critical section to ensure we don't   migrate CPU's after the critical
 section but before we set the CPU.

---
 sys/kern/kern_ktr.c | 31 +++++++++++++++++--------------
 sys/sys/ktr.h       | 15 ++++++---------
 2 files changed, 23 insertions(+), 23 deletions(-)

diff --git a/sys/kern/kern_ktr.c b/sys/kern/kern_ktr.c
index 8902ca57c294..06372b93ee4a 100644
--- a/sys/kern/kern_ktr.c
+++ b/sys/kern/kern_ktr.c
@@ -38,19 +38,22 @@
 #include "opt_ktr.h"
 
 #include <sys/param.h>
-#include <sys/types.h>
 #include <sys/cons.h>
-#include <sys/time.h>
 #include <sys/kernel.h>
 #include <sys/ktr.h>
 #include <sys/libkern.h>
 #include <sys/sysctl.h>
 #include <sys/systm.h>
+#include <sys/time.h>
 #include <machine/globals.h>
 #include <machine/stdarg.h>
 
 #include <ddb/ddb.h>
 
+#ifndef KTR_ENTRIES
+#define	KTR_ENTRIES	1024
+#endif
+
 #ifndef KTR_MASK
 #define	KTR_MASK	(KTR_GEN)
 #endif
@@ -126,30 +129,30 @@ ktr_tracepoint(u_int mask, const char *format, u_long arg1, u_long arg2,
 		return;
 	if ((ktr_mask & mask) == 0)
 		return;
-#ifdef KTR_EXTEND
-	if (((1 << KTR_CPU) & ktr_cpumask) == 0)
-		return;
-#endif
 	savecrit = critical_enter();
+	if (((1 << KTR_CPU) & ktr_cpumask) == 0) {
+		critical_exit(savecrit);
+		return;
+	}
+	atomic_clear_int(&ktr_cpumask, 1 << KTR_CPU);
 	do {
 		saveindex = ktr_idx;
 		newindex = (saveindex + 1) & (KTR_ENTRIES - 1);
 	} while (atomic_cmpset_rel_int(&ktr_idx, saveindex, newindex) == 0);
 	entry = &ktr_buf[saveindex];
-	critical_exit(savecrit);
-	if (ktr_mask & KTR_LOCK)
-		/*
-		 * We can't use nanotime with KTR_LOCK, it would cause
-		 * endless recursion, at least under the Intel
-		 * architecture.
-		 */		   
+	/*
+	 * XXX: The ktr_cpumask atomic ops should make this unnecessary.
+	 */
+	if ((ktr_mask & (KTR_LOCK | KTR_WITNESS)) != 0)
 		getnanotime(&entry->ktr_tv);
 	else
 		nanotime(&entry->ktr_tv);
+	atomic_set_int(&ktr_cpumask, 1 << KTR_CPU);
+	entry->ktr_cpu = KTR_CPU;
+	critical_exit(savecrit);
 #ifdef KTR_EXTEND
 	entry->ktr_filename = filename;
 	entry->ktr_line = line;
-	entry->ktr_cpu = KTR_CPU;
 	va_start(ap, format);
 	vsnprintf(entry->ktr_desc, KTRDESCSIZE, format, ap);
 	va_end(ap);
diff --git a/sys/sys/ktr.h b/sys/sys/ktr.h
index 5c39adb8d0f2..fe087c767054 100644
--- a/sys/sys/ktr.h
+++ b/sys/sys/ktr.h
@@ -65,7 +65,7 @@
 #define KTR_NFS		0x00040000		/* The obvious */
 #define KTR_VOP		0x00080000		/* The obvious */
 #define KTR_VM		0x00100000		/* The virtual memory system */
-#define KTR_IDLELOOP	0x00200000		/* checks done in the idle process */
+#define KTR_WITNESS	0x00200000
 #define	KTR_RUNQ	0x00400000		/* Run queue */
 #define	KTR_ALL		0x007fffff
 
@@ -91,16 +91,17 @@
 
 #include <sys/time.h>
 
-struct ktr_entry {
-	struct	timespec ktr_tv;
-#ifdef KTR_EXTEND
 #ifndef KTRDESCSIZE
 #define KTRDESCSIZE 80
 #endif
+
+struct ktr_entry {
+	struct	timespec ktr_tv;
+	int	ktr_cpu;
+#ifdef KTR_EXTEND
 	char	ktr_desc[KTRDESCSIZE];
 	const	char *ktr_filename;
 	int	ktr_line;
-	int	ktr_cpu;
 #else
 	const	char *ktr_desc;
 	u_long	ktr_parm1;
@@ -125,10 +126,6 @@ extern struct ktr_entry ktr_buf[];
 #endif /* !LOCORE */
 #ifdef KTR
 
-#ifndef KTR_ENTRIES
-#define	KTR_ENTRIES	1024
-#endif
-
 #ifdef KTR_EXTEND
 void	ktr_tracepoint(u_int mask, const char *filename, u_int line,
 		       const char *format, ...) __printflike(4, 5);