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Date:      Fri, 22 Sep 2017 20:01:12 +0000 (UTC)
From:      Conrad Meyer <cem@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r323935 - head/sys/kern
Message-ID:  <201709222001.v8MK1CdR023641@repo.freebsd.org>
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Author: cem
Date: Fri Sep 22 20:01:12 2017
New Revision: 323935
URL: https://svnweb.freebsd.org/changeset/base/323935

Log:
  ddb(4): Add 'show badstacks' command to show witness badstacks
  
  Add a DDB command that mirrors sysctl debug.witness.badstacks.
  
  Reported by:	rstone
  Reviewed by:	rstone
  Sponsored by:	Dell EMC Isilon
  Differential Revision:	https://reviews.freebsd.org/D12468

Modified:
  head/sys/kern/subr_witness.c

Modified: head/sys/kern/subr_witness.c
==============================================================================
--- head/sys/kern/subr_witness.c	Fri Sep 22 17:58:57 2017	(r323934)
+++ head/sys/kern/subr_witness.c	Fri Sep 22 20:01:12 2017	(r323935)
@@ -2539,31 +2539,18 @@ DB_SHOW_COMMAND(witness, db_witness_display)
 }
 #endif
 
-static int
-sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS)
+static void
+sbuf_print_witness_badstacks(struct sbuf *sb)
 {
 	struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2;
 	struct witness *tmp_w1, *tmp_w2, *w1, *w2;
-	struct sbuf *sb;
 	u_int w_rmatrix1, w_rmatrix2;
-	int error, generation, i, j;
+	int generation, i, j;
 
 	tmp_data1 = NULL;
 	tmp_data2 = NULL;
 	tmp_w1 = NULL;
 	tmp_w2 = NULL;
-	if (witness_watch < 1) {
-		error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning));
-		return (error);
-	}
-	if (witness_cold) {
-		error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold));
-		return (error);
-	}
-	error = 0;
-	sb = sbuf_new(NULL, NULL, badstack_sbuf_size, SBUF_AUTOEXTEND);
-	if (sb == NULL)
-		return (ENOMEM);
 
 	/* Allocate and init temporary storage space. */
 	tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO);
@@ -2683,13 +2670,55 @@ restart:
 	free(tmp_data2, M_TEMP);
 	free(tmp_w1, M_TEMP);
 	free(tmp_w2, M_TEMP);
+}
 
+static int
+sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS)
+{
+	struct sbuf *sb;
+	int error;
+
+	if (witness_watch < 1) {
+		error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning));
+		return (error);
+	}
+	if (witness_cold) {
+		error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold));
+		return (error);
+	}
+	error = 0;
+	sb = sbuf_new(NULL, NULL, badstack_sbuf_size, SBUF_AUTOEXTEND);
+	if (sb == NULL)
+		return (ENOMEM);
+
+	sbuf_print_witness_badstacks(sb);
+
 	sbuf_finish(sb);
 	error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1);
 	sbuf_delete(sb);
 
 	return (error);
 }
+
+#ifdef DDB
+static int
+sbuf_db_printf_drain(void *arg __unused, const char *data, int len)
+{
+
+	return (db_printf("%.*s", len, data));
+}
+
+DB_SHOW_COMMAND(badstacks, db_witness_badstacks)
+{
+	struct sbuf sb;
+	char buffer[128];
+
+	sbuf_new(&sb, buffer, sizeof(buffer), SBUF_FIXEDLEN);
+	sbuf_set_drain(&sb, sbuf_db_printf_drain, NULL);
+	sbuf_print_witness_badstacks(&sb);
+	sbuf_finish(&sb);
+}
+#endif
 
 static int
 sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS)

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