diff options
Diffstat (limited to 'lib/fault-inject.c')
| -rw-r--r-- | lib/fault-inject.c | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/lib/fault-inject.c b/lib/fault-inject.c new file mode 100644 index 000000000000..a7cb3afd132a --- /dev/null +++ b/lib/fault-inject.c @@ -0,0 +1,183 @@ +#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/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, ×) < 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) + +/* + * This code is stolen from failmalloc-1.0 + * http://www.nongnu.org/failmalloc/ + */ + +int should_fail(struct fault_attr *attr, ssize_t size) +{ + if (atomic_read(&attr->times) == 0) + return 0; + + if (atomic_read(&attr->space) > size) { + atomic_sub(size, &attr->space); + return 0; + } + + if (attr->interval > 1) { + attr->count++; + if (attr->count % attr->interval) + return 0; + } + + if (attr->probability > random32() % 100) + goto fail; + + return 0; + +fail: + fail_dump(attr); + + if (atomic_read(&attr->times) != -1) + atomic_dec_not_zero(&attr->times); + + return 1; +} + +#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS + +static void debugfs_ul_set(void *data, u64 val) +{ + *(unsigned long *)data = val; +} + +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); +} + +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; + + 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); + + if (!attr->dentries.probability_file || !attr->dentries.interval_file + || !attr->dentries.times_file || !attr->dentries.space_file + || !attr->dentries.verbose_file) + goto fail; + + return 0; +fail: + cleanup_fault_attr_dentries(attr); + return -ENOMEM; +} + +#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */ |