Implement sbuf_prf(), which takes an sbuf and outputs it

to stdout in the non-kernel case and to the console+log
in the kernel case.  For the kernel case it hooks the
putbuf() machinery underneath printf(9) so that the buffer
is written completely atomically and without a copy into
another temporary buffer.  This is useful for fixing
compound console/log messages that become broken and
interleaved when multiple threads are competing for the
console.

Reviewed by:	ken, imp
Sponsored by:	Netflix

1 files changed, 34 insertions, 12 deletions

diff --git a/sys/kern/subr_prf.c b/sys/kern/subr_prf.c
index e78863830c7b..cc38d17ac113 100644
--- a/sys/kern/subr_prf.c
+++ b/sys/kern/subr_prf.c
@@ -411,6 +411,23 @@ vprintf(const char *fmt, va_list ap)
 }
 
 static void
+prf_putbuf(char *bufr, int flags, int pri)
+{
+
+	if (flags & TOLOG)
+		msglogstr(bufr, pri, /*filter_cr*/1);
+
+	if (flags & TOCONS) {
+		if ((panicstr == NULL) && (constty != NULL))
+			msgbuf_addstr(&consmsgbuf, -1,
+			    bufr, /*filter_cr*/ 0);
+
+		if ((constty == NULL) ||(always_console_output))
+			cnputs(bufr);
+	}
+}
+
+static void
 putbuf(int c, struct putchar_arg *ap)
 {
 	/* Check if no console output buffer was provided. */
@@ -431,18 +448,7 @@ putbuf(int c, struct putchar_arg *ap)
 
 		/* Check if the buffer needs to be flushed. */
 		if (ap->remain == 2 || c == '\n') {
-
-			if (ap->flags & TOLOG)
-				msglogstr(ap->p_bufr, ap->pri, /*filter_cr*/1);
-
-			if (ap->flags & TOCONS) {
-				if ((panicstr == NULL) && (constty != NULL))
-					msgbuf_addstr(&consmsgbuf, -1,
-					    ap->p_bufr, /*filter_cr*/ 0);
-
-				if ((constty == NULL) ||(always_console_output))
-					cnputs(ap->p_bufr);
-			}
+			prf_putbuf(ap->p_bufr, ap->flags, ap->pri);
 
 			ap->p_next = ap->p_bufr;
 			ap->remain = ap->n_bufr;
@@ -1221,3 +1227,19 @@ counted_warning(unsigned *counter, const char *msg)
 	}
 }
 #endif
+
+#ifdef _KERNEL
+void
+sbuf_putbuf(struct sbuf *sb)
+{
+
+	prf_putbuf(sbuf_data(sb), TOLOG | TOCONS, -1);
+}
+#else
+void
+sbuf_putbuf(struct sbuf *sb)
+{
+
+	printf("%s", sbuf_data(sb));
+}
+#endif