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Diffstat (limited to 'lib/fault-inject.c')
| -rw-r--r-- | lib/fault-inject.c | 240 |
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, ×) < 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 */ |