summaryrefslogtreecommitdiffstats
path: root/lib/fault-inject.c
diff options
context:
space:
mode:
Diffstat (limited to 'lib/fault-inject.c')
-rw-r--r--lib/fault-inject.c240
1 files changed, 240 insertions, 0 deletions
diff --git a/lib/fault-inject.c b/lib/fault-inject.c
new file mode 100644
index 000000000..adb2f9355
--- /dev/null
+++ b/lib/fault-inject.c
@@ -0,0 +1,240 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/random.h>
+#include <linux/sched.h>
+#include <linux/stat.h>
+#include <linux/types.h>
+#include <linux/fs.h>
+#include <linux/export.h>
+#include <linux/interrupt.h>
+#include <linux/stacktrace.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 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;
+}
+EXPORT_SYMBOL_GPL(setup_fault_attr);
+
+static void fail_dump(struct fault_attr *attr)
+{
+ if (attr->verbose > 0 && __ratelimit(&attr->ratelimit_state)) {
+ printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure.\n"
+ "name %pd, interval %lu, probability %lu, "
+ "space %d, times %d\n", attr->dname,
+ attr->interval, attr->probability,
+ atomic_read(&attr->space),
+ atomic_read(&attr->times));
+ 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_task() && task->make_it_fail;
+}
+
+#define MAX_STACK_TRACE_DEPTH 32
+
+#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
+
+static bool fail_stacktrace(struct fault_attr *attr)
+{
+ int depth = attr->stacktrace_depth;
+ unsigned long entries[MAX_STACK_TRACE_DEPTH];
+ int n, nr_entries;
+ bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);
+
+ if (depth == 0)
+ return found;
+
+ nr_entries = stack_trace_save(entries, depth, 1);
+ for (n = 0; n < 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)
+{
+ return true;
+}
+
+#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
+
+/*
+ * This code is stolen from failmalloc-1.0
+ * http://www.nongnu.org/failmalloc/
+ */
+
+bool should_fail_ex(struct fault_attr *attr, ssize_t size, int flags)
+{
+ if (in_task()) {
+ unsigned int fail_nth = READ_ONCE(current->fail_nth);
+
+ if (fail_nth) {
+ fail_nth--;
+ WRITE_ONCE(current->fail_nth, fail_nth);
+ if (!fail_nth)
+ goto fail;
+
+ return false;
+ }
+ }
+
+ /* No need to check any other properties if the probability is 0 */
+ if (attr->probability == 0)
+ return false;
+
+ 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 <= prandom_u32_max(100))
+ return false;
+
+ if (!fail_stacktrace(attr))
+ return false;
+
+fail:
+ if (!(flags & FAULT_NOWARN))
+ fail_dump(attr);
+
+ if (atomic_read(&attr->times) != -1)
+ atomic_dec_not_zero(&attr->times);
+
+ return true;
+}
+
+bool should_fail(struct fault_attr *attr, ssize_t size)
+{
+ return should_fail_ex(attr, size, 0);
+}
+EXPORT_SYMBOL_GPL(should_fail);
+
+#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
+
+static int debugfs_ul_set(void *data, u64 val)
+{
+ *(unsigned long *)data = val;
+ return 0;
+}
+
+static int debugfs_ul_get(void *data, u64 *val)
+{
+ *val = *(unsigned long *)data;
+ return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
+
+static void debugfs_create_ul(const char *name, umode_t mode,
+ struct dentry *parent, unsigned long *value)
+{
+ debugfs_create_file(name, mode, parent, value, &fops_ul);
+}
+
+#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
+
+static int debugfs_stacktrace_depth_set(void *data, u64 val)
+{
+ *(unsigned long *)data =
+ min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH);
+
+ return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get,
+ debugfs_stacktrace_depth_set, "%llu\n");
+
+static void debugfs_create_stacktrace_depth(const char *name, umode_t mode,
+ struct dentry *parent,
+ unsigned long *value)
+{
+ debugfs_create_file(name, mode, parent, value, &fops_stacktrace_depth);
+}
+
+#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
+
+struct dentry *fault_create_debugfs_attr(const char *name,
+ struct dentry *parent, struct fault_attr *attr)
+{
+ umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
+ struct dentry *dir;
+
+ dir = debugfs_create_dir(name, parent);
+ if (IS_ERR(dir))
+ return dir;
+
+ debugfs_create_ul("probability", mode, dir, &attr->probability);
+ debugfs_create_ul("interval", mode, dir, &attr->interval);
+ debugfs_create_atomic_t("times", mode, dir, &attr->times);
+ debugfs_create_atomic_t("space", mode, dir, &attr->space);
+ debugfs_create_ul("verbose", mode, dir, &attr->verbose);
+ debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir,
+ &attr->ratelimit_state.interval);
+ debugfs_create_u32("verbose_ratelimit_burst", mode, dir,
+ &attr->ratelimit_state.burst);
+ debugfs_create_bool("task-filter", mode, dir, &attr->task_filter);
+
+#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
+ debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir,
+ &attr->stacktrace_depth);
+ debugfs_create_ul("require-start", mode, dir, &attr->require_start);
+ debugfs_create_ul("require-end", mode, dir, &attr->require_end);
+ debugfs_create_ul("reject-start", mode, dir, &attr->reject_start);
+ debugfs_create_ul("reject-end", mode, dir, &attr->reject_end);
+#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
+
+ attr->dname = dget(dir);
+ return dir;
+}
+EXPORT_SYMBOL_GPL(fault_create_debugfs_attr);
+
+#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */