[PATCH] fault injection: split up stacktrace filter Kconfig option

There is no prompt for CONFIG_STACKTRACE, so FAULT_INJECTION cannot be
selected without LOCKDEP enabled.  (found by Paolo 'Blaisorblade'
Giarrusso)

In order to fix such broken Kconfig dependency, this patch splits up the
stacktrace filter support for fault injection by new Kconfig option, which
enables to use fault injection on the architecture which doesn't have
general stacktrace support.

Cc: "Paolo 'Blaisorblade' Giarrusso" <blaisorblade@yahoo.it>
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

lib/Kconfig.debug

@@ -411,8 +411,6 @@ config LKDTM
 config FAULT_INJECTION
 	bool "Fault-injection framework"
 	depends on DEBUG_KERNEL
-	depends on STACKTRACE
-	select FRAME_POINTER
 	help
 	  Provide fault-injection framework.
 	  For more details, see Documentation/fault-injection/.
@@ -440,3 +438,11 @@ config FAULT_INJECTION_DEBUG_FS
 	depends on FAULT_INJECTION && SYSFS && DEBUG_FS
 	help
 	  Enable configuration of fault-injection capabilities via debugfs.
+
+config FAULT_INJECTION_STACKTRACE_FILTER
+	bool "stacktrace filter for fault-injection capabilities"
+	depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
+	select STACKTRACE
+	select FRAME_POINTER
+	help
+	  Provide stacktrace filter for fault-injection capabilities

lib/fault-inject.c

@@ -55,7 +55,7 @@ static bool fail_task(struct fault_attr *attr, struct task_struct *task)
 
 #define MAX_STACK_TRACE_DEPTH 32
 
-#if defined(CONFIG_STACKTRACE)
+#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
 
 static bool fail_stacktrace(struct fault_attr *attr)
 {
@@ -90,17 +90,10 @@ static bool fail_stacktrace(struct fault_attr *attr)
 
 static inline bool fail_stacktrace(struct fault_attr *attr)
 {
-	static bool firsttime = true;
-
-	if (firsttime) {
-		printk(KERN_WARNING
-		"This architecture does not implement save_stack_trace()\n");
-		firsttime = false;
-	}
-	return false;
+	return true;
 }
 
-#endif
+#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
 
 /*
  * This code is stolen from failmalloc-1.0
@@ -217,6 +210,8 @@ void cleanup_fault_attr_dentries(struct fault_attr *attr)
 	debugfs_remove(attr->dentries.task_filter_file);
 	attr->dentries.task_filter_file = NULL;
 
+#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
+
 	debugfs_remove(attr->dentries.stacktrace_depth_file);
 	attr->dentries.stacktrace_depth_file = NULL;
 
@@ -232,6 +227,8 @@ void cleanup_fault_attr_dentries(struct fault_attr *attr)
 	debugfs_remove(attr->dentries.reject_end_file);
 	attr->dentries.reject_end_file = NULL;
 
+#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
+
 	if (attr->dentries.dir)
 		WARN_ON(!simple_empty(attr->dentries.dir));
 
@@ -269,6 +266,13 @@ int init_fault_attr_dentries(struct fault_attr *attr, const char *name)
 	attr->dentries.task_filter_file = debugfs_create_bool("task-filter",
 						mode, dir, &attr->task_filter);
 
+	if (!attr->dentries.probability_file || !attr->dentries.interval_file ||
+	    !attr->dentries.times_file || !attr->dentries.space_file ||
+	    !attr->dentries.verbose_file || !attr->dentries.task_filter_file)
+		goto fail;
+
+#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
+
 	attr->dentries.stacktrace_depth_file =
 		debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
 			"stacktrace-depth", mode, dir, &attr->stacktrace_depth);
@@ -285,18 +289,15 @@ int init_fault_attr_dentries(struct fault_attr *attr, const char *name)
 	attr->dentries.reject_end_file =
 		debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
 
-
-	if (!attr->dentries.probability_file || !attr->dentries.interval_file
-	    || !attr->dentries.times_file || !attr->dentries.space_file
-	    || !attr->dentries.verbose_file || !attr->dentries.task_filter_file
-	    || !attr->dentries.stacktrace_depth_file
-	    || !attr->dentries.require_start_file
-	    || !attr->dentries.require_end_file
-	    || !attr->dentries.reject_start_file
-	    || !attr->dentries.reject_end_file
-	    )
+	if (!attr->dentries.stacktrace_depth_file ||
+	    !attr->dentries.require_start_file ||
+	    !attr->dentries.require_end_file ||
+	    !attr->dentries.reject_start_file ||
+	    !attr->dentries.reject_end_file)
 		goto fail;
 
+#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
+
 	return 0;
 fail:
 	cleanup_fault_attr_dentries(attr);