Add a drain function for struct sysctl_req, and use it for a variety of

handlers, some of which had to do awkward things to get a large enough
FIXEDLEN buffer.

Note that some sysctl handlers were explicitly outputting a trailing NUL
byte.  This behaviour was preserved, though it should not be necessary.

Reviewed by:	phk

1 files changed, 6 insertions, 14 deletions

diff --git a/sys/kern/subr_lock.c b/sys/kern/subr_lock.c
index 61263f9..530ebc5 100644
--- a/sys/kern/subr_lock.c
+++ b/sys/kern/subr_lock.c
@@ -191,8 +191,7 @@ struct lock_prof_cpu *lp_cpu[MAXCPU];
 volatile int lock_prof_enable = 0;
 static volatile int lock_prof_resetting;
 
-/* SWAG: sbuf size = avg stat. line size * number of locks */
-#define LPROF_SBUF_SIZE		256 * 400
+#define LPROF_SBUF_SIZE		256
 
 static int lock_prof_rejected;
 static int lock_prof_skipspin;
@@ -384,8 +383,6 @@ lock_prof_type_stats(struct lock_prof_type *type, struct sbuf *sb, int spin,
 				continue;
 			lock_prof_sum(l, &lp, i, spin, t);
 			lock_prof_output(&lp, sb);
-			if (sbuf_overflowed(sb))
-				return;
 		}
 	}
 }
@@ -393,13 +390,11 @@ lock_prof_type_stats(struct lock_prof_type *type, struct sbuf *sb, int spin,
 static int
 dump_lock_prof_stats(SYSCTL_HANDLER_ARGS)
 {
-	static int multiplier = 1;
 	struct sbuf *sb;
 	int error, cpu, t;
 	int enabled;
 
-retry_sbufops:
-	sb = sbuf_new(NULL, NULL, LPROF_SBUF_SIZE * multiplier, SBUF_FIXEDLEN);
+	sb = sbuf_new_for_sysctl(NULL, NULL, LPROF_SBUF_SIZE, req);
 	sbuf_printf(sb, "\n%8s %9s %11s %11s %11s %6s %6s %2s %6s %s\n",
 	    "max", "wait_max", "total", "wait_total", "count", "avg", "wait_avg", "cnt_hold", "cnt_lock", "name");
 	enabled = lock_prof_enable;
@@ -411,16 +406,13 @@ retry_sbufops:
 			continue;
 		lock_prof_type_stats(&lp_cpu[cpu]->lpc_types[0], sb, 0, t);
 		lock_prof_type_stats(&lp_cpu[cpu]->lpc_types[1], sb, 1, t);
-		if (sbuf_overflowed(sb)) {
-			sbuf_delete(sb);
-			multiplier++;
-			goto retry_sbufops;
-		}
 	}
 	lock_prof_enable = enabled;
 
-	sbuf_finish(sb);
-	error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1);
+	error = sbuf_finish(sb);
+	/* Output a trailing NUL. */
+	if (error == 0)
+		error = SYSCTL_OUT(req, "", 1);
 	sbuf_delete(sb);
 	return (error);
 }