Fix making kernel dumps from the debugger by creating a command

for it. Do not not expect a developer to call doadump(). Calling
doadump does not necessarily work when it's declared static. Nor
does it necessarily do what was intended in the context of text
dumps. The dump command always creates a core dump.

Move printing of error messages from doadump to the dump command,
now that we don't have to worry about being called from DDB.

sys/ddb/db_command.c

@@ -44,6 +44,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/signalvar.h>
 #include <sys/systm.h>
 #include <sys/cons.h>
+#include <sys/conf.h>
 #include <sys/watchdog.h>
 #include <sys/kernel.h>
 
@@ -64,6 +65,7 @@ db_addr_t	db_last_addr;
 db_addr_t	db_prev;
 db_addr_t	db_next;
 
+static db_cmdfcn_t	db_dump;
 static db_cmdfcn_t	db_fncall;
 static db_cmdfcn_t	db_gdb;
 static db_cmdfcn_t	db_halt;
@@ -102,6 +104,7 @@ static struct command db_cmds[] = {
 	{ "w",		db_write_cmd,		CS_MORE|CS_SET_DOT, 0 },
 	{ "delete",	db_delete_cmd,		0,	0 },
 	{ "d",		db_delete_cmd,		0,	0 },
+	{ "dump",	db_dump,		0,	0 },
 	{ "break",	db_breakpoint_cmd,	0,	0 },
 	{ "b",		db_breakpoint_cmd,	0,	0 },
 	{ "dwatch",	db_deletewatch_cmd,	0,	0 },
@@ -526,6 +529,27 @@ db_error(s)
 	kdb_reenter();
 }
 
+static void
+db_dump(db_expr_t dummy, boolean_t dummy2, db_expr_t dummy3, char *dummy4)
+{
+	int error;
+
+	error = doadump(FALSE);
+	if (error) {
+		db_printf("Cannot dump: ");
+		switch (error) {
+		case EBUSY:
+			db_printf("debugger got invoked while dumping.\n");
+			break;
+		case ENXIO:
+			db_printf("no dump device specified.\n");
+			break;
+		default:
+			db_printf("unknown error (error=%d).\n", error);
+			break;
+		}
+	}
+}
 
 /*
  * Call random function:

sys/kern/kern_shutdown.c

@@ -233,30 +233,32 @@ print_uptime(void)
 	printf("%lds\n", (long)ts.tv_sec);
 }
 
-static void
-doadump(void)
+int
+doadump(boolean_t textdump)
 {
+	boolean_t coredump;
 
-	/*
-	 * Sometimes people have to call this from the kernel debugger. 
-	 * (if 'panic' can not dump)
-	 * Give them a clue as to why they can't dump.
-	 */
-	if (dumper.dumper == NULL) {
-		printf("Cannot dump. Device not defined or unavailable.\n");
-		return;
-	}
+	if (dumping)
+		return (EBUSY);
+	if (dumper.dumper == NULL)
+		return (ENXIO);
 
 	savectx(&dumppcb);
 	dumptid = curthread->td_tid;
 	dumping++;
+
+	coredump = TRUE;
 #ifdef DDB
-	if (textdump_pending)
+	if (textdump && textdump_pending) {
+		coredump = FALSE;
 		textdump_dumpsys(&dumper);
-	else
+	}
 #endif
+	if (coredump)
 		dumpsys(&dumper);
+
 	dumping--;
+	return (0);
 }
 
 static int
@@ -425,7 +427,7 @@ kern_reboot(int howto)
 	EVENTHANDLER_INVOKE(shutdown_post_sync, howto);
 
 	if ((howto & (RB_HALT|RB_DUMP)) == RB_DUMP && !cold && !dumping) 
-		doadump();
+		doadump(TRUE);
 
 	/* Now that we're going to really halt the system... */
 	EVENTHANDLER_INVOKE(shutdown_final, howto);

sys/sys/conf.h

@@ -332,6 +332,7 @@ struct dumperinfo {
 int set_dumper(struct dumperinfo *);
 int dump_write(struct dumperinfo *, void *, vm_offset_t, off_t, size_t);
 void dumpsys(struct dumperinfo *);
+int doadump(boolean_t);
 extern int dumping;		/* system is dumping */
 
 #endif /* _KERNEL */