1 files changed, 336 insertions, 0 deletions
diff --git a/lib/fault-inject.c b/lib/fault-inject.c
new file mode 100644
index 000000000000..d143c0faf248
--- /dev/null
+++ b/lib/fault-inject.c
@@ -0,0 +1,336 @@
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/random.h>
+#include <linux/stat.h>
+#include <linux/types.h>
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/unwind.h>
+#include <linux/stacktrace.h>
+#include <linux/kallsyms.h>
+#include <linux/fault-inject.h>
+
+/*
+ * setup_fault_attr() is a helper function for various __setup handlers, so it
+ * returns 0 on error, because that is what __setup handlers do.
+ */
+int __init setup_fault_attr(struct fault_attr *attr, char *str)
+{
+	unsigned long probability;
+	unsigned long interval;
+	int times;
+	int space;
+
+	/* "<interval>,<probability>,<space>,<times>" */
+	if (sscanf(str, "%lu,%lu,%d,%d",
+			&interval, &probability, &space, &times) < 4) {
+		printk(KERN_WARNING
+			"FAULT_INJECTION: failed to parse arguments\n");
+		return 0;
+	}
+
+	attr->probability = probability;
+	attr->interval = interval;
+	atomic_set(&attr->times, times);
+	atomic_set(&attr->space, space);
+
+	return 1;
+}
+
+static void fail_dump(struct fault_attr *attr)
+{
+	if (attr->verbose > 0)
+		printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure\n");
+	if (attr->verbose > 1)
+		dump_stack();
+}
+
+#define atomic_dec_not_zero(v)		atomic_add_unless((v), -1, 0)
+
+static bool fail_task(struct fault_attr *attr, struct task_struct *task)
+{
+	return !in_interrupt() && task->make_it_fail;
+}
+
+#define MAX_STACK_TRACE_DEPTH 32
+
+#ifdef CONFIG_STACK_UNWIND
+
+static asmlinkage int fail_stacktrace_callback(struct unwind_frame_info *info,
+						void *arg)
+{
+	int depth;
+	struct fault_attr *attr = arg;
+	bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);
+
+	for (depth = 0; depth < attr->stacktrace_depth
+			&& unwind(info) == 0 && UNW_PC(info); depth++) {
+		if (arch_unw_user_mode(info))
+			break;
+		if (attr->reject_start <= UNW_PC(info) &&
+			       UNW_PC(info) < attr->reject_end)
+			return false;
+		if (attr->require_start <= UNW_PC(info) &&
+			       UNW_PC(info) < attr->require_end)
+			found = true;
+	}
+	return found;
+}
+
+static bool fail_stacktrace(struct fault_attr *attr)
+{
+	struct unwind_frame_info info;
+
+	return unwind_init_running(&info, fail_stacktrace_callback, attr);
+}
+
+#elif defined(CONFIG_STACKTRACE)
+
+static bool fail_stacktrace(struct fault_attr *attr)
+{
+	struct stack_trace trace;
+	int depth = attr->stacktrace_depth;
+	unsigned long entries[MAX_STACK_TRACE_DEPTH];
+	int n;
+	bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);
+
+	if (depth == 0)
+		return found;
+
+	trace.nr_entries = 0;
+	trace.entries = entries;
+	trace.max_entries = depth;
+	trace.skip = 1;
+	trace.all_contexts = 0;
+
+	save_stack_trace(&trace, NULL);
+	for (n = 0; n < trace.nr_entries; n++) {
+		if (attr->reject_start <= entries[n] &&
+			       entries[n] < attr->reject_end)
+			return false;
+		if (attr->require_start <= entries[n] &&
+			       entries[n] < attr->require_end)
+			found = true;
+	}
+	return found;
+}
+
+#else
+
+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;
+}
+
+#endif
+
+/*
+ * This code is stolen from failmalloc-1.0
+ * http://www.nongnu.org/failmalloc/
+ */
+
+bool should_fail(struct fault_attr *attr, ssize_t size)
+{
+	if (attr->task_filter && !fail_task(attr, current))
+		return false;
+
+	if (atomic_read(&attr->times) == 0)
+		return false;
+
+	if (atomic_read(&attr->space) > size) {
+		atomic_sub(size, &attr->space);
+		return false;
+	}
+
+	if (attr->interval > 1) {
+		attr->count++;
+		if (attr->count % attr->interval)
+			return false;
+	}
+
+	if (attr->probability <= random32() % 100)
+		return false;
+
+	if (!fail_stacktrace(attr))
+		return false;
+
+	fail_dump(attr);
+
+	if (atomic_read(&attr->times) != -1)
+		atomic_dec_not_zero(&attr->times);
+
+	return true;
+}
+
+#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
+
+static void debugfs_ul_set(void *data, u64 val)
+{
+	*(unsigned long *)data = val;
+}
+
+static void debugfs_ul_set_MAX_STACK_TRACE_DEPTH(void *data, u64 val)
+{
+	*(unsigned long *)data =
+		val < MAX_STACK_TRACE_DEPTH ?
+		val : MAX_STACK_TRACE_DEPTH;
+}
+
+static u64 debugfs_ul_get(void *data)
+{
+	return *(unsigned long *)data;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
+
+static struct dentry *debugfs_create_ul(const char *name, mode_t mode,
+				struct dentry *parent, unsigned long *value)
+{
+	return debugfs_create_file(name, mode, parent, value, &fops_ul);
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get,
+			debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n");
+
+static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
+	const char *name, mode_t mode,
+	struct dentry *parent, unsigned long *value)
+{
+	return debugfs_create_file(name, mode, parent, value,
+				   &fops_ul_MAX_STACK_TRACE_DEPTH);
+}
+
+static void debugfs_atomic_t_set(void *data, u64 val)
+{
+	atomic_set((atomic_t *)data, val);
+}
+
+static u64 debugfs_atomic_t_get(void *data)
+{
+	return atomic_read((atomic_t *)data);
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get,
+			debugfs_atomic_t_set, "%lld\n");
+
+static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode,
+				struct dentry *parent, atomic_t *value)
+{
+	return debugfs_create_file(name, mode, parent, value, &fops_atomic_t);
+}
+
+void cleanup_fault_attr_dentries(struct fault_attr *attr)
+{
+	debugfs_remove(attr->dentries.probability_file);
+	attr->dentries.probability_file = NULL;
+
+	debugfs_remove(attr->dentries.interval_file);
+	attr->dentries.interval_file = NULL;
+
+	debugfs_remove(attr->dentries.times_file);
+	attr->dentries.times_file = NULL;
+
+	debugfs_remove(attr->dentries.space_file);
+	attr->dentries.space_file = NULL;
+
+	debugfs_remove(attr->dentries.verbose_file);
+	attr->dentries.verbose_file = NULL;
+
+	debugfs_remove(attr->dentries.task_filter_file);
+	attr->dentries.task_filter_file = NULL;
+
+	debugfs_remove(attr->dentries.stacktrace_depth_file);
+	attr->dentries.stacktrace_depth_file = NULL;
+
+	debugfs_remove(attr->dentries.require_start_file);
+	attr->dentries.require_start_file = NULL;
+
+	debugfs_remove(attr->dentries.require_end_file);
+	attr->dentries.require_end_file = NULL;
+
+	debugfs_remove(attr->dentries.reject_start_file);
+	attr->dentries.reject_start_file = NULL;
+
+	debugfs_remove(attr->dentries.reject_end_file);
+	attr->dentries.reject_end_file = NULL;
+
+	if (attr->dentries.dir)
+		WARN_ON(!simple_empty(attr->dentries.dir));
+
+	debugfs_remove(attr->dentries.dir);
+	attr->dentries.dir = NULL;
+}
+
+int init_fault_attr_dentries(struct fault_attr *attr, const char *name)
+{
+	mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
+	struct dentry *dir;
+
+	memset(&attr->dentries, 0, sizeof(attr->dentries));
+
+	dir = debugfs_create_dir(name, NULL);
+	if (!dir)
+		goto fail;
+	attr->dentries.dir = dir;
+
+	attr->dentries.probability_file =
+		debugfs_create_ul("probability", mode, dir, &attr->probability);
+
+	attr->dentries.interval_file =
+		debugfs_create_ul("interval", mode, dir, &attr->interval);
+
+	attr->dentries.times_file =
+		debugfs_create_atomic_t("times", mode, dir, &attr->times);
+
+	attr->dentries.space_file =
+		debugfs_create_atomic_t("space", mode, dir, &attr->space);
+
+	attr->dentries.verbose_file =
+		debugfs_create_ul("verbose", mode, dir, &attr->verbose);
+
+	attr->dentries.task_filter_file = debugfs_create_bool("task-filter",
+						mode, dir, &attr->task_filter);
+
+	attr->dentries.stacktrace_depth_file =
+		debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
+			"stacktrace-depth", mode, dir, &attr->stacktrace_depth);
+
+	attr->dentries.require_start_file =
+		debugfs_create_ul("require-start", mode, dir, &attr->require_start);
+
+	attr->dentries.require_end_file =
+		debugfs_create_ul("require-end", mode, dir, &attr->require_end);
+
+	attr->dentries.reject_start_file =
+		debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
+
+	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
+	    )
+		goto fail;
+
+	return 0;
+fail:
+	cleanup_fault_attr_dentries(attr);
+	return -ENOMEM;
+}
+
+#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */