Commit 6ff1cb35 authored by Akinobu Mita's avatar Akinobu Mita Committed by Linus Torvalds
Browse files

[PATCH] fault-injection capabilities infrastructure 

This patch provides base functions implement to fault-injection
capabilities.

- The function should_fail() is taken from failmalloc-1.0
  (http://www.nongnu.org/failmalloc/

)

[akpm@osdl.org: cleanups, comments, add __init]
Cc: <okuji@enbug.org>
Signed-off-by: default avatarAkinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: default avatarDon Mullis <dwm@meer.net>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent de1ba09b

include/linux/fault-inject.h

0 → 100644
+69 −0
Original line number Diff line number Diff line 
#ifndef _LINUX_FAULT_INJECT_H

#define _LINUX_FAULT_INJECT_H



#ifdef CONFIG_FAULT_INJECTION



#include <linux/types.h>

#include <linux/debugfs.h>

#include <asm/atomic.h>



/*

 * For explanation of the elements of this struct, see

 * Documentation/fault-injection/fault-injection.txt

 */

struct fault_attr {

	unsigned long probability;

	unsigned long interval;

	atomic_t times;

	atomic_t space;

	unsigned long verbose;



	unsigned long count;



#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS



	struct {

		struct dentry *dir;



		struct dentry *probability_file;

		struct dentry *interval_file;

		struct dentry *times_file;

		struct dentry *space_file;

		struct dentry *verbose_file;

	} dentries;



#endif

};



#define FAULT_ATTR_INITIALIZER {				\

		.interval = 1,					\

		.times = ATOMIC_INIT(1),			\

	}



#define DECLARE_FAULT_ATTR(name) struct fault_attr name = FAULT_ATTR_INITIALIZER

int setup_fault_attr(struct fault_attr *attr, char *str);

void should_fail_srandom(unsigned long entropy);

int should_fail(struct fault_attr *attr, ssize_t size);



#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS



int init_fault_attr_dentries(struct fault_attr *attr, const char *name);

void cleanup_fault_attr_dentries(struct fault_attr *attr);



#else /* CONFIG_FAULT_INJECTION_DEBUG_FS */



static inline int init_fault_attr_dentries(struct fault_attr *attr,

					  const char *name)

{

	return -ENODEV;

}



static inline void cleanup_fault_attr_dentries(struct fault_attr *attr)

{

}



#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */



#endif /* CONFIG_FAULT_INJECTION */



#endif /* _LINUX_FAULT_INJECT_H */

lib/Kconfig.debug

+12 −0
Original line number Diff line number Diff line
@@ -413,3 +413,15 @@ config LKDTM 


	Documentation on how to use the module can be found in

	drivers/misc/lkdtm.c



config FAULT_INJECTION

	bool



config FAULT_INJECTION_DEBUG_FS

	bool "Debugfs entries for fault-injection capabilities"

	depends on FAULT_INJECTION && SYSFS

	select DEBUG_FS

	help

	  This option enable configuration of fault-injection capabilities via

	  debugfs.

lib/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -55,6 +55,7 @@ obj-$(CONFIG_SMP) += percpu_counter.o 
obj-$(CONFIG_AUDIT_GENERIC) += audit.o



obj-$(CONFIG_SWIOTLB) += swiotlb.o

obj-$(CONFIG_FAULT_INJECTION) += fault-inject.o



lib-$(CONFIG_GENERIC_BUG) += bug.o

lib/fault-inject.c

0 → 100644
+183 −0
Original line number Diff line number Diff line 
#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, &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)



/*

 * 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 */