Add a timestamp to the msgbuf output in order to determine when when

messages were printed.

This can be enabled with the kern.msgbuf_show_timestamp sysctl

PR:		kern/161553
Reviewed by:	avg
Submitted by:	Arnaud Lacombe <lacombar@gmail.com>
Approved by:	cperciva
MFC after:	1 month

1 files changed, 45 insertions, 8 deletions

diff --git a/sys/kern/subr_msgbuf.c b/sys/kern/subr_msgbuf.c
index cd9c55149775..2d141e36c6fa 100644
--- a/sys/kern/subr_msgbuf.c
+++ b/sys/kern/subr_msgbuf.c
@@ -32,8 +32,10 @@
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/lock.h>
+#include <sys/kernel.h>
 #include <sys/mutex.h>
 #include <sys/msgbuf.h>
+#include <sys/sysctl.h>
 
 /*
  * Maximum number conversion buffer length: uintmax_t in base 2, plus <>
@@ -47,6 +49,14 @@
 static u_int msgbuf_cksum(struct msgbuf *mbp);
 
 /*
+ *
+ */
+static int msgbuf_show_timestamp = 0;
+SYSCTL_INT(_kern, OID_AUTO, msgbuf_show_timestamp, CTLFLAG_RW | CTLFLAG_TUN,
+    &msgbuf_show_timestamp, 0, "Show timestamp in msgbuf");
+TUNABLE_INT("kern.msgbuf_show_timestamp", &msgbuf_show_timestamp);
+
+/*
  * Initialize a message buffer of the specified size at the specified
  * location. This also zeros the buffer area.
  */
@@ -60,7 +70,7 @@ msgbuf_init(struct msgbuf *mbp, void *ptr, int size)
 	msgbuf_clear(mbp);
 	mbp->msg_magic = MSG_MAGIC;
 	mbp->msg_lastpri = -1;
-	mbp->msg_needsnl = 0;
+	mbp->msg_flags = 0;
 	bzero(&mbp->msg_lock, sizeof(mbp->msg_lock));
 	mtx_init(&mbp->msg_lock, "msgbuf", NULL, MTX_SPIN);
 }
@@ -95,7 +105,7 @@ msgbuf_reinit(struct msgbuf *mbp, void *ptr, int size)
 
 	mbp->msg_lastpri = -1;
 	/* Assume that the old message buffer didn't end in a newline. */
-	mbp->msg_needsnl = 1;
+	mbp->msg_flags |= MSGBUF_NEEDNL;
 	bzero(&mbp->msg_lock, sizeof(mbp->msg_lock));
 	mtx_init(&mbp->msg_lock, "msgbuf", NULL, MTX_SPIN);
 }
@@ -134,7 +144,7 @@ msgbuf_getcount(struct msgbuf *mbp)
  * The caller should hold the message buffer spinlock.
  */
 static inline void
-msgbuf_do_addchar(struct msgbuf *mbp, u_int *seq, int c)
+__msgbuf_do_addchar(struct msgbuf * const mbp, u_int * const seq, const int c)
 {
 	u_int pos;
 
@@ -149,6 +159,33 @@ msgbuf_do_addchar(struct msgbuf *mbp, u_int *seq, int c)
 	*seq = MSGBUF_SEQNORM(mbp, *seq + 1);
 }
 
+static inline void
+msgbuf_do_addchar(struct msgbuf * const mbp, u_int * const seq, const int c)
+{
+
+	if (msgbuf_show_timestamp &&
+	    (mbp->msg_flags & MSGBUF_NEXT_NEW_LINE) != 0) {
+		char buf[32];
+		char const *bufp;
+		struct timespec ts;
+		int err;
+
+		getnanouptime(&ts);
+		err = snprintf(buf, sizeof (buf), "[%jd.%ld] ",
+		    (intmax_t)ts.tv_sec, ts.tv_nsec / 1000);
+
+		for (bufp = buf; *bufp != '\0'; bufp++)
+			__msgbuf_do_addchar(mbp, seq, *bufp);
+
+		mbp->msg_flags &= ~MSGBUF_NEXT_NEW_LINE;
+	}
+
+	__msgbuf_do_addchar(mbp, seq, c);
+
+	if (c == '\n')
+		mbp->msg_flags |= MSGBUF_NEXT_NEW_LINE;
+}
+
 /*
  * Append a character to a message buffer.
  */
@@ -207,10 +244,10 @@ msgbuf_addstr(struct msgbuf *mbp, int pri, char *str, int filter_cr)
 	 * did not end with a newline.  If that is the case, we need to
 	 * insert a newline before this string.
 	 */
-	if (mbp->msg_lastpri != pri && mbp->msg_needsnl != 0) {
+	if (mbp->msg_lastpri != pri && (mbp->msg_flags & MSGBUF_NEEDNL) != 0) {
 
 		msgbuf_do_addchar(mbp, &seq, '\n');
-		mbp->msg_needsnl = 0;
+		mbp->msg_flags &= ~MSGBUF_NEEDNL;
 	}
 
 	for (i = 0; i < len; i++) {
@@ -219,7 +256,7 @@ msgbuf_addstr(struct msgbuf *mbp, int pri, char *str, int filter_cr)
 		 * (and therefore prefix_len != 0), then we need a priority
 		 * prefix for this line.
 		 */
-		if (mbp->msg_needsnl == 0 && prefix_len != 0) {
+		if ((mbp->msg_flags & MSGBUF_NEEDNL) == 0 && prefix_len != 0) {
 			int j;
 
 			for (j = 0; j < prefix_len; j++)
@@ -242,9 +279,9 @@ msgbuf_addstr(struct msgbuf *mbp, int pri, char *str, int filter_cr)
 		 * we need to insert a new prefix or insert a newline later.
 		 */
 		if (str[i] == '\n')
-			mbp->msg_needsnl = 0;
+			mbp->msg_flags &= ~MSGBUF_NEEDNL;
 		else
-			mbp->msg_needsnl = 1;
+			mbp->msg_flags |= MSGBUF_NEEDNL;
 
 		msgbuf_do_addchar(mbp, &seq, str[i]);
 	}