This adds a new selftest module which can be used to test sysfs, which would otherwise require using an existing driver. This lets us muck with a template driver to test breaking things without affecting system behaviour or requiring the dependencies of a real device driver.

A series of 28 tests are added. Support for using two device types are supported:

* misc * block

Contrary to sysctls, sysfs requires a full write to happen at once, and so we reduce the digit tests to single writes. Two main sysfs knobs are provided for testing reading/storing, one which doesn't incur any delays and another which can incur programmed delays. What locks are held, if any, are configurable, at module load time, or through dynamic configuration at run time.

Since sysfs is a technically filesystem, but a pseudo one, which requires a kernel user, our test_sysfs module and respective test script embraces fstests format for tests in the kernel ring bufffer. Likewise, a scraper for kernel crashes is provided which matches what fstests does as well.

Two tests are kept disabled as they are a demonstration of what not to do as it can cause a deadlock with sysfs. These tests provides a mechanism to easily show proof and demo how the deadlock can happen:

Demos the deadlock with a device specific lock ./tools/testing/selftests/sysfs/sysfs.sh -t 0027

Demos the deadlock with rtnl_lock() ./tools/testing/selftests/sysfs/sysfs.sh -t 0028

Drivers should *avoid* sharing a lock on rmmod and on sysfs ops.

This selftests will shortly be expanded upon with more tests which require further kernel changes in order to provide better test coverage.

Signed-off-by: Luis Chamberlain mcgrof@kernel.org --- MAINTAINERS | 7 + lib/Kconfig.debug | 12 + lib/Makefile | 1 + lib/test_sysfs.c | 894 ++++++++++++++++++ tools/testing/selftests/sysfs/Makefile | 12 + tools/testing/selftests/sysfs/config | 2 + tools/testing/selftests/sysfs/settings | 1 + tools/testing/selftests/sysfs/sysfs.sh | 1197 ++++++++++++++++++++++++ 8 files changed, 2126 insertions(+) create mode 100644 lib/test_sysfs.c create mode 100644 tools/testing/selftests/sysfs/Makefile create mode 100644 tools/testing/selftests/sysfs/config create mode 100644 tools/testing/selftests/sysfs/settings create mode 100755 tools/testing/selftests/sysfs/sysfs.sh

diff --git a/MAINTAINERS b/MAINTAINERS index 5f87f622ac18..8b458c4dd577 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -18393,6 +18393,13 @@ L: linux-mmc@vger.kernel.org S: Maintained F: drivers/mmc/host/sdhci-pci-dwc-mshc.c

+SYSFS TEST DRIVER +M: Luis Chamberlain mcgrof@kernel.org +L: linux-kernel@vger.kernel.org +S: Maintained +F: lib/test_sysfs.c +F: tools/testing/selftests/sysfs/ + SYSTEM CONFIGURATION (SYSCON) M: Lee Jones lee.jones@linaro.org M: Arnd Bergmann arnd@arndb.de diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 44a6df361016..ec531b423c0e 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -2344,6 +2344,18 @@ config TEST_SYSCTL

If unsure, say N.

+config TEST_SYSFS + tristate "sysfs test driver" + depends on SYSFS + depends on NET + depends on BLOCK + help + This builds the "test_sysfs" module. This driver enables to test the + sysfs file system safely without affecting production knobs which + might alter system functionality. + + If unsure, say N. + config BITFIELD_KUNIT tristate "KUnit test bitfield functions at runtime" depends on KUNIT diff --git a/lib/Makefile b/lib/Makefile index 364c23f15578..741c1be29781 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -61,6 +61,7 @@ obj-$(CONFIG_TEST_FIRMWARE) += test_firmware.o obj-$(CONFIG_TEST_BITOPS) += test_bitops.o CFLAGS_test_bitops.o += -Werror obj-$(CONFIG_TEST_SYSCTL) += test_sysctl.o +obj-$(CONFIG_TEST_SYSFS) += test_sysfs.o obj-$(CONFIG_TEST_HASH) += test_hash.o test_siphash.o obj-$(CONFIG_TEST_IDA) += test_ida.o obj-$(CONFIG_KASAN_KUNIT_TEST) += test_kasan.o diff --git a/lib/test_sysfs.c b/lib/test_sysfs.c new file mode 100644 index 000000000000..2a6ec072da60 --- /dev/null +++ b/lib/test_sysfs.c @@ -0,0 +1,894 @@ +// SPDX-License-Identifier: GPL-2.0-or-later OR copyleft-next-0.3.1 +/* + * Copyright (C) 2021 Luis Chamberlain mcgrof@kernel.org + * + * sysfs test driver + * + * This module allows us to add race conditions which we can test for + * against the sysfs filesystem. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/init.h> +#include <linux/list.h> +#include <linux/module.h> +#include <linux/printk.h> +#include <linux/fs.h> +#include <linux/miscdevice.h> +#include <linux/slab.h> +#include <linux/uaccess.h> +#include <linux/async.h> +#include <linux/delay.h> +#include <linux/vmalloc.h> +#include <linux/debugfs.h> +#include <linux/rtnetlink.h> +#include <linux/genhd.h> +#include <linux/blkdev.h> + +static bool enable_lock; +module_param(enable_lock, bool_enable_only, 0644); +MODULE_PARM_DESC(enable_lock, + "enable locking on reads / stores from the start"); + +static bool enable_lock_on_rmmod; +module_param(enable_lock_on_rmmod, bool_enable_only, 0644); +MODULE_PARM_DESC(enable_lock_on_rmmod, + "enable locking on rmmod"); + +static bool use_rtnl_lock; +module_param(use_rtnl_lock, bool_enable_only, 0644); +MODULE_PARM_DESC(use_rtnl_lock, + "use an rtnl_lock instead of the device mutex_lock"); + +static unsigned int write_delay_msec_y = 500; +module_param_named(write_delay_msec_y, write_delay_msec_y, uint, 0644); +MODULE_PARM_DESC(write_delay_msec_y, "msec write delay for writes to y"); + +static unsigned int test_devtype; +module_param_named(devtype, test_devtype, uint, 0644); +MODULE_PARM_DESC(devtype, "device type to register"); + +static bool enable_busy_alloc; +module_param(enable_busy_alloc, bool_enable_only, 0644); +MODULE_PARM_DESC(enable_busy_alloc, "do a fake allocation during writes"); + +static bool enable_debugfs; +module_param(enable_debugfs, bool_enable_only, 0644); +MODULE_PARM_DESC(enable_debugfs, "enable a few debugfs files"); + +static bool enable_verbose_writes; +module_param(enable_verbose_writes, bool_enable_only, 0644); +MODULE_PARM_DESC(enable_debugfs, "enable stores to print verbose information"); + +static unsigned int delay_rmmod_ms; +module_param_named(delay_rmmod_ms, delay_rmmod_ms, uint, 0644); +MODULE_PARM_DESC(delay_rmmod_ms, "if set how many ms to delay rmmod before device deletion"); + +static bool enable_verbose_rmmod; +module_param(enable_verbose_rmmod, bool_enable_only, 0644); +MODULE_PARM_DESC(enable_verbose_rmmod, "enable verbose print messages on rmmod"); + +static int sysfs_test_major; + +/** + * test_config - used for configuring how the sysfs test device will behave + * + * @enable_lock: if enabled a lock will be used when reading/storing variables + * @enable_lock_on_rmmod: if enabled a lock will be used when reading/storing + * sysfs attributes, but it will also be used to lock on rmmod. This is + * useful to test for a deadlock and should serve as an example of what + * drivers should *not* do. + * @use_rtnl_lock: if enabled instead of configuration specific mutex, we'll + * use the rtnl_lock. If your test case is modifying this on the fly + * while doing other stores / reads, things will break as a lock can be + * left contending. Best is that tests use this knob serially, without + * allowing userspace to modify other knobs while this one changes. + * @write_delay_msec_y: the amount of delay to use when writing to y + * @enable_busy_alloc: if enabled we'll do a large allocation between + * writes. We immediately free right away. We also schedule to give the + * kernel some time to re-use any memory we don't need. This is intened + * to mimic typical driver behaviour. + */ +struct test_config { + bool enable_lock; + bool enable_lock_on_rmmod; + bool use_rtnl_lock; + unsigned int write_delay_msec_y; + bool enable_busy_alloc; +}; + +/** + * enum sysfs_test_devtype - sysfs device type + * @TESTDEV_TYPE_MISC: misc device type + * @TESTDEV_TYPE_BLOCK: use a block device for the sysfs test device. + */ +enum sysfs_test_devtype { + TESTDEV_TYPE_MISC = 0, + TESTDEV_TYPE_BLOCK, +}; + +/** + * sysfs_test_device - test device to help test sysfs + * + * @devtype: the type of device to use + * @config: configuration for the test + * @config_mutex: protects configuration of test + * @misc_dev: we use a misc device under the hood + * @disk: represents a disk when used as a block device + * @dev: pointer to misc_dev's own struct device + * @dev_idx: unique ID for test device + * @x: variable we can use to test read / store + * @y: slow variable we can use to test read / store + */ +struct sysfs_test_device { + enum sysfs_test_devtype devtype; + struct test_config config; + struct mutex config_mutex; + struct miscdevice misc_dev; + struct gendisk *disk; + struct device *dev; + int dev_idx; + int x; + int y; +}; + +static struct sysfs_test_device *first_test_dev; + +static struct miscdevice *dev_to_misc_dev(struct device *dev) +{ + return dev_get_drvdata(dev); +} + +static struct sysfs_test_device *misc_dev_to_test_dev(struct miscdevice *misc_dev) +{ + return container_of(misc_dev, struct sysfs_test_device, misc_dev); +} + +static struct sysfs_test_device *devblock_to_test_dev(struct device *dev) +{ + return (struct sysfs_test_device *)dev_to_disk(dev)->private_data; +} + +static struct sysfs_test_device *devmisc_to_testdev(struct device *dev) +{ + struct miscdevice *misc_dev; + + misc_dev = dev_to_misc_dev(dev); + return misc_dev_to_test_dev(misc_dev); +} + +static struct sysfs_test_device *dev_to_test_dev(struct device *dev) +{ + if (test_devtype == TESTDEV_TYPE_MISC) + return devmisc_to_testdev(dev); + else if (test_devtype == TESTDEV_TYPE_BLOCK) + return devblock_to_test_dev(dev); + return NULL; +} + +static void test_dev_config_lock(struct sysfs_test_device *test_dev) +{ + struct test_config *config = &test_dev->config; + + if (config->enable_lock) { + if (config->use_rtnl_lock) + rtnl_lock(); + else + mutex_lock(&test_dev->config_mutex); + } +} + +static void test_dev_config_unlock(struct sysfs_test_device *test_dev) +{ + struct test_config *config = &test_dev->config; + + if (config->enable_lock) { + if (config->use_rtnl_lock) + rtnl_unlock(); + else + mutex_unlock(&test_dev->config_mutex); + } +} + +static void test_dev_config_lock_rmmod(struct sysfs_test_device *test_dev) +{ + struct test_config *config = &test_dev->config; + + if (config->enable_lock_on_rmmod) + test_dev_config_lock(test_dev); +} + +static void test_dev_config_unlock_rmmod(struct sysfs_test_device *test_dev) +{ + struct test_config *config = &test_dev->config; + + if (config->enable_lock_on_rmmod) + test_dev_config_unlock(test_dev); +} + +static void free_test_dev_sysfs(struct sysfs_test_device *test_dev) +{ + if (test_dev) { + kfree_const(test_dev->misc_dev.name); + test_dev->misc_dev.name = NULL; + kfree(test_dev); + test_dev = NULL; + } +} + +static void test_sysfs_reset_vals(struct sysfs_test_device *test_dev) +{ + test_dev->x = 3; + test_dev->y = 4; +} + +static ssize_t config_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct sysfs_test_device *test_dev = dev_to_test_dev(dev); + struct test_config *config = &test_dev->config; + int len = 0; + + test_dev_config_lock(test_dev); + + len += sysfs_emit_at(buf, len, "Configuration for: %s\n", + dev_name(dev)); + len += sysfs_emit_at(buf, len, "x:\t%d\n", test_dev->x); + len += sysfs_emit_at(buf, len, "y:\t%d\n", test_dev->y); + len += sysfs_emit_at(buf, len, "enable_lock:\t%s\n", + config->enable_lock ? "true" : "false"); + len += sysfs_emit_at(buf, len, "enable_lock_on_rmmmod:\t%s\n", + config->enable_lock_on_rmmod ? "true" : "false"); + len += sysfs_emit_at(buf, len, "use_rtnl_lock:\t%s\n", + config->use_rtnl_lock ? "true" : "false"); + len += sysfs_emit_at(buf, len, "write_delay_msec_y:\t%d\n", + config->write_delay_msec_y); + len += sysfs_emit_at(buf, len, "enable_busy_alloc:\t%s\n", + config->enable_busy_alloc ? "true" : "false"); + len += sysfs_emit_at(buf, len, "enable_debugfs:\t%s\n", + enable_debugfs ? "true" : "false"); + len += sysfs_emit_at(buf, len, "enable_verbose_writes:\t%s\n", + enable_verbose_writes ? "true" : "false"); + + test_dev_config_unlock(test_dev); + + return len; +} +static DEVICE_ATTR_RO(config); + +static ssize_t reset_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct sysfs_test_device *test_dev = dev_to_test_dev(dev); + struct test_config *config = &test_dev->config; + + /* + * We compromise and simplify this condition and do not use a lock + * here as the lock type can change. + */ + config->enable_lock = false; + config->enable_lock_on_rmmod = false; + config->use_rtnl_lock = false; + config->enable_busy_alloc = false; + test_sysfs_reset_vals(test_dev); + + dev_info(dev, "reset\n"); + + return count; +} +static DEVICE_ATTR_WO(reset); + +static void test_dev_busy_alloc(struct sysfs_test_device *test_dev) +{ + struct test_config *config = &test_dev->config; + char *ignore; + + if (!config->enable_busy_alloc) + return; + + ignore = kzalloc(sizeof(struct sysfs_test_device) * 10, GFP_KERNEL); + kfree(ignore); + + schedule(); +} + +static ssize_t test_dev_x_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct sysfs_test_device *test_dev = dev_to_test_dev(dev); + int ret; + + test_dev_busy_alloc(test_dev); + test_dev_config_lock(test_dev); + + ret = kstrtoint(buf, 10, &test_dev->x); + if (ret) + count = ret; + + if (enable_verbose_writes) + dev_info(test_dev->dev, "wrote x = %d\n", test_dev->x); + + test_dev_config_unlock(test_dev); + + return count; +} + +static ssize_t test_dev_x_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct sysfs_test_device *test_dev = dev_to_test_dev(dev); + int ret; + + test_dev_config_lock(test_dev); + ret = sysfs_emit(buf, "%d\n", test_dev->x); + test_dev_config_unlock(test_dev); + + return ret; +} +static DEVICE_ATTR_RW(test_dev_x); + +static ssize_t test_dev_y_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct sysfs_test_device *test_dev = dev_to_test_dev(dev); + struct test_config *config; + int y; + int ret; + + test_dev_busy_alloc(test_dev); + test_dev_config_lock(test_dev); + + config = &test_dev->config; + + ret = kstrtoint(buf, 10, &y); + if (ret) + count = ret; + + msleep(config->write_delay_msec_y); + test_dev->y = test_dev->x + y + 7; + + if (enable_verbose_writes) + dev_info(test_dev->dev, "wrote y = %d\n", test_dev->y); + + test_dev_config_unlock(test_dev); + + return count; +} + +static ssize_t test_dev_y_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct sysfs_test_device *test_dev = dev_to_test_dev(dev); + int ret; + + test_dev_config_lock(test_dev); + ret = sysfs_emit(buf, "%d\n", test_dev->y); + test_dev_config_unlock(test_dev); + + return ret; +} +static DEVICE_ATTR_RW(test_dev_y); + +static ssize_t config_enable_lock_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct sysfs_test_device *test_dev = dev_to_test_dev(dev); + struct test_config *config = &test_dev->config; + int ret; + int val; + + ret = kstrtoint(buf, 10, &val); + if (ret) + return ret; + + /* + * We compromise for simplicty and do not lock when changing + * locking configuration, with the assumption userspace tests + * will know this. + */ + if (val) + config->enable_lock = true; + else + config->enable_lock = false; + + return count; +} + +static ssize_t config_enable_lock_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct sysfs_test_device *test_dev = dev_to_test_dev(dev); + struct test_config *config = &test_dev->config; + ssize_t ret; + + test_dev_config_lock(test_dev); + ret = sysfs_emit(buf, "%d\n", config->enable_lock); + test_dev_config_unlock(test_dev); + + return ret; +} +static DEVICE_ATTR_RW(config_enable_lock); + +static ssize_t config_enable_lock_on_rmmod_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct sysfs_test_device *test_dev = dev_to_test_dev(dev); + struct test_config *config = &test_dev->config; + int ret; + int val; + + ret = kstrtoint(buf, 10, &val); + if (ret) + return ret; + + test_dev_config_lock(test_dev); + if (val) + config->enable_lock_on_rmmod = true; + else + config->enable_lock_on_rmmod = false; + test_dev_config_unlock(test_dev); + + return count; +} + +static ssize_t config_enable_lock_on_rmmod_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct sysfs_test_device *test_dev = dev_to_test_dev(dev); + struct test_config *config = &test_dev->config; + ssize_t ret; + + test_dev_config_lock(test_dev); + ret = sysfs_emit(buf, "%d\n", config->enable_lock_on_rmmod); + test_dev_config_unlock(test_dev); + + return ret; +} +static DEVICE_ATTR_RW(config_enable_lock_on_rmmod); + +static ssize_t config_use_rtnl_lock_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct sysfs_test_device *test_dev = dev_to_test_dev(dev); + struct test_config *config = &test_dev->config; + int ret; + int val; + + ret = kstrtoint(buf, 10, &val); + if (ret) + return ret; + + /* + * We compromise and simplify this condition and do not use a lock + * here as the lock type can change. + */ + if (val) + config->use_rtnl_lock = true; + else + config->use_rtnl_lock = false; + + return count; +} + +static ssize_t config_use_rtnl_lock_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct sysfs_test_device *test_dev = dev_to_test_dev(dev); + struct test_config *config = &test_dev->config; + + return sysfs_emit(buf, "%d\n", config->use_rtnl_lock); +} +static DEVICE_ATTR_RW(config_use_rtnl_lock); + +static ssize_t config_write_delay_msec_y_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct sysfs_test_device *test_dev = dev_to_test_dev(dev); + struct test_config *config = &test_dev->config; + int ret; + int val; + + ret = kstrtoint(buf, 10, &val); + if (ret) + return ret; + + test_dev_config_lock(test_dev); + config->write_delay_msec_y = val; + test_dev_config_unlock(test_dev); + + return count; +} + +static ssize_t config_write_delay_msec_y_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct sysfs_test_device *test_dev = dev_to_test_dev(dev); + struct test_config *config = &test_dev->config; + + return sysfs_emit(buf, "%d\n", config->write_delay_msec_y); +} +static DEVICE_ATTR_RW(config_write_delay_msec_y); + +static ssize_t config_enable_busy_alloc_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct sysfs_test_device *test_dev = dev_to_test_dev(dev); + struct test_config *config = &test_dev->config; + int ret; + int val; + + ret = kstrtoint(buf, 10, &val); + if (ret) + return ret; + + test_dev_config_lock(test_dev); + config->enable_busy_alloc = val; + test_dev_config_unlock(test_dev); + + return count; +} + +static ssize_t config_enable_busy_alloc_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct sysfs_test_device *test_dev = dev_to_test_dev(dev); + struct test_config *config = &test_dev->config; + + return sysfs_emit(buf, "%d\n", config->enable_busy_alloc); +} +static DEVICE_ATTR_RW(config_enable_busy_alloc); + +#define TEST_SYSFS_DEV_ATTR(name) (&dev_attr_##name.attr) + +static struct attribute *test_dev_attrs[] = { + /* Generic driver knobs go here */ + TEST_SYSFS_DEV_ATTR(config), + TEST_SYSFS_DEV_ATTR(reset), + + /* These are used to test sysfs */ + TEST_SYSFS_DEV_ATTR(test_dev_x), + TEST_SYSFS_DEV_ATTR(test_dev_y), + + /* + * These are configuration knobs to modify how we test sysfs when + * doing reads / stores. + */ + TEST_SYSFS_DEV_ATTR(config_enable_lock), + TEST_SYSFS_DEV_ATTR(config_enable_lock_on_rmmod), + TEST_SYSFS_DEV_ATTR(config_use_rtnl_lock), + TEST_SYSFS_DEV_ATTR(config_write_delay_msec_y), + TEST_SYSFS_DEV_ATTR(config_enable_busy_alloc), + + NULL, +}; + +ATTRIBUTE_GROUPS(test_dev); + +static int sysfs_test_dev_alloc_miscdev(struct sysfs_test_device *test_dev) +{ + struct miscdevice *misc_dev; + + misc_dev = &test_dev->misc_dev; + misc_dev->minor = MISC_DYNAMIC_MINOR; + misc_dev->name = kasprintf(GFP_KERNEL, "test_sysfs%d", test_dev->dev_idx); + if (!misc_dev->name) { + pr_err("Cannot alloc misc_dev->name\n"); + return -ENOMEM; + } + misc_dev->groups = test_dev_groups; + + return 0; +} + +static int testdev_open(struct block_device *bdev, fmode_t mode) +{ + return -EINVAL; +} + +static void testdev_submit_bio(struct bio *bio) +{ +} + +static void testdev_slot_free_notify(struct block_device *bdev, + unsigned long index) +{ +} + +static int testdev_rw_page(struct block_device *bdev, sector_t sector, + struct page *page, unsigned int op) +{ + return -EOPNOTSUPP; +} + +static const struct block_device_operations sysfs_testdev_ops = { + .open = testdev_open, + .submit_bio = testdev_submit_bio, + .swap_slot_free_notify = testdev_slot_free_notify, + .rw_page = testdev_rw_page, + .owner = THIS_MODULE +}; + +static int sysfs_test_dev_alloc_blockdev(struct sysfs_test_device *test_dev) +{ + int ret = -ENOMEM; + + test_dev->disk = blk_alloc_disk(NUMA_NO_NODE); + if (!test_dev->disk) { + pr_err("Error allocating disk structure for device %d\n", + test_dev->dev_idx); + goto out; + } + + test_dev->disk->major = sysfs_test_major; + test_dev->disk->first_minor = test_dev->dev_idx + 1; + test_dev->disk->fops = &sysfs_testdev_ops; + test_dev->disk->private_data = test_dev; + snprintf(test_dev->disk->disk_name, sizeof(test_dev->disk->disk_name), + "test_sysfs%d", test_dev->dev_idx); + set_capacity(test_dev->disk, 0); + blk_queue_flag_set(QUEUE_FLAG_NONROT, test_dev->disk->queue); + blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, test_dev->disk->queue); + blk_queue_physical_block_size(test_dev->disk->queue, PAGE_SIZE); + blk_queue_max_discard_sectors(test_dev->disk->queue, UINT_MAX); + blk_queue_flag_set(QUEUE_FLAG_DISCARD, test_dev->disk->queue); + + return 0; +out: + return ret; +} + +static struct sysfs_test_device *alloc_test_dev_sysfs(int idx) +{ + struct sysfs_test_device *test_dev; + int ret; + + switch (test_devtype) { + case TESTDEV_TYPE_MISC: + fallthrough; + case TESTDEV_TYPE_BLOCK: + break; + default: + return NULL; + } + + test_dev = kzalloc(sizeof(struct sysfs_test_device), GFP_KERNEL); + if (!test_dev) + goto err_out; + + mutex_init(&test_dev->config_mutex); + test_dev->dev_idx = idx; + test_dev->devtype = test_devtype; + + if (test_dev->devtype == TESTDEV_TYPE_MISC) { + ret = sysfs_test_dev_alloc_miscdev(test_dev); + if (ret) + goto err_out_free; + } else if (test_dev->devtype == TESTDEV_TYPE_BLOCK) { + ret = sysfs_test_dev_alloc_blockdev(test_dev); + if (ret) + goto err_out_free; + } + return test_dev; + +err_out_free: + kfree(test_dev); + test_dev = NULL; +err_out: + return NULL; +} + +static int register_test_dev_sysfs_misc(struct sysfs_test_device *test_dev) +{ + int ret; + + ret = misc_register(&test_dev->misc_dev); + if (ret) + return ret; + + test_dev->dev = test_dev->misc_dev.this_device; + + return 0; +} + +static int register_test_dev_sysfs_block(struct sysfs_test_device *test_dev) +{ + int ret; + + ret = device_add_disk(NULL, test_dev->disk, test_dev_groups); + if (ret) { + blk_cleanup_disk(test_dev->disk); + return ret; + } + + test_dev->dev = disk_to_dev(test_dev->disk); + + return 0; +} + +static struct sysfs_test_device *register_test_dev_sysfs(void) +{ + struct sysfs_test_device *test_dev = NULL; + int ret; + + test_dev = alloc_test_dev_sysfs(0); + if (!test_dev) + goto out; + + if (test_dev->devtype == TESTDEV_TYPE_MISC) { + ret = register_test_dev_sysfs_misc(test_dev); + if (ret) { + pr_err("could not register misc device: %d\n", ret); + goto out_free_dev; + } + } else if (test_dev->devtype == TESTDEV_TYPE_BLOCK) { + ret = register_test_dev_sysfs_block(test_dev); + if (ret) { + pr_err("could not register block device: %d\n", ret); + goto out_free_dev; + } + } + + dev_info(test_dev->dev, "interface ready\n"); + +out: + return test_dev; +out_free_dev: + free_test_dev_sysfs(test_dev); + return NULL; +} + +static struct sysfs_test_device *register_test_dev_set_config(void) +{ + struct sysfs_test_device *test_dev; + struct test_config *config; + + test_dev = register_test_dev_sysfs(); + if (!test_dev) + return NULL; + + config = &test_dev->config; + + if (enable_lock) + config->enable_lock = true; + if (enable_lock_on_rmmod) + config->enable_lock_on_rmmod = true; + if (use_rtnl_lock) + config->use_rtnl_lock = true; + if (enable_busy_alloc) + config->enable_busy_alloc = true; + + config->write_delay_msec_y = write_delay_msec_y; + test_sysfs_reset_vals(test_dev); + + return test_dev; +} + +static void unregister_test_dev_sysfs_misc(struct sysfs_test_device *test_dev) +{ + misc_deregister(&test_dev->misc_dev); +} + +static void unregister_test_dev_sysfs_block(struct sysfs_test_device *test_dev) +{ + del_gendisk(test_dev->disk); + blk_cleanup_disk(test_dev->disk); +} + +static void unregister_test_dev_sysfs(struct sysfs_test_device *test_dev) +{ + test_dev_config_lock_rmmod(test_dev); + + dev_info(test_dev->dev, "removing interface\n"); + + if (test_dev->devtype == TESTDEV_TYPE_MISC) + unregister_test_dev_sysfs_misc(test_dev); + else if (test_dev->devtype == TESTDEV_TYPE_BLOCK) + unregister_test_dev_sysfs_block(test_dev); + + test_dev_config_unlock_rmmod(test_dev); + + free_test_dev_sysfs(test_dev); +} + +static struct dentry *debugfs_dir; + +/* When read represents how many times we have reset the first_test_dev */ +static u8 reset_first_test_dev; + +static ssize_t read_reset_first_test_dev(struct file *file, + char __user *user_buf, + size_t count, loff_t *ppos) +{ + ssize_t len; + char buf[32]; + + reset_first_test_dev++; + len = sprintf(buf, "%d\n", reset_first_test_dev); + return simple_read_from_buffer(user_buf, count, ppos, buf, len); +} + +static ssize_t write_reset_first_test_dev(struct file *file, + const char __user *user_buf, + size_t count, loff_t *ppos) +{ + if (!try_module_get(THIS_MODULE)) + return -ENODEV; + + if (!first_test_dev) { + module_put(THIS_MODULE); + return -ENODEV; + } + + dev_info(first_test_dev->dev, "going to reset first interface ...\n"); + + unregister_test_dev_sysfs(first_test_dev); + first_test_dev = register_test_dev_set_config(); + + dev_info(first_test_dev->dev, "first interface reset complete\n"); + + module_put(THIS_MODULE); + + return count; +} + +static const struct file_operations fops_reset_first_test_dev = { + .read = read_reset_first_test_dev, + .write = write_reset_first_test_dev, + .open = simple_open, + .owner = THIS_MODULE, + .llseek = default_llseek, +}; + +static int __init test_sysfs_init(void) +{ + first_test_dev = register_test_dev_set_config(); + if (!first_test_dev) + return -ENOMEM; + + if (!enable_debugfs) + return 0; + + debugfs_dir = debugfs_create_dir("test_sysfs", NULL); + if (!debugfs_dir) { + unregister_test_dev_sysfs(first_test_dev); + return -ENOMEM; + } + + debugfs_create_file("reset_first_test_dev", 0600, debugfs_dir, + NULL, &fops_reset_first_test_dev); + return 0; +} +module_init(test_sysfs_init); + +static void __exit test_sysfs_exit(void) +{ + if (enable_debugfs) + debugfs_remove(debugfs_dir); + if (delay_rmmod_ms) + msleep(delay_rmmod_ms); + unregister_test_dev_sysfs(first_test_dev); + if (enable_verbose_rmmod) + pr_info("unregister_test_dev_sysfs() completed\n"); + first_test_dev = NULL; +} +module_exit(test_sysfs_exit); + +MODULE_AUTHOR("Luis Chamberlain mcgrof@kernel.org"); +MODULE_LICENSE("GPL"); diff --git a/tools/testing/selftests/sysfs/Makefile b/tools/testing/selftests/sysfs/Makefile new file mode 100644 index 000000000000..fde99caa2338 --- /dev/null +++ b/tools/testing/selftests/sysfs/Makefile @@ -0,0 +1,12 @@ +# SPDX-License-Identifier: GPL-2.0-only +# Makefile for sysfs selftests. + +# No binaries, but make sure arg-less "make" doesn't trigger "run_tests". +all: + +TEST_PROGS := sysfs.sh + +include ../lib.mk + +# Nothing to clean up. +clean: diff --git a/tools/testing/selftests/sysfs/config b/tools/testing/selftests/sysfs/config new file mode 100644 index 000000000000..9196f452ecd5 --- /dev/null +++ b/tools/testing/selftests/sysfs/config @@ -0,0 +1,2 @@ +CONFIG_SYSFS=m +CONFIG_TEST_SYSFS=m diff --git a/tools/testing/selftests/sysfs/settings b/tools/testing/selftests/sysfs/settings new file mode 100644 index 000000000000..ae36db2b3200 --- /dev/null +++ b/tools/testing/selftests/sysfs/settings @@ -0,0 +1 @@ +timeout=200 diff --git a/tools/testing/selftests/sysfs/sysfs.sh b/tools/testing/selftests/sysfs/sysfs.sh new file mode 100755 index 000000000000..802651d78427 --- /dev/null +++ b/tools/testing/selftests/sysfs/sysfs.sh @@ -0,0 +1,1197 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0-or-later +# Copyright (C) 2021 Luis Chamberlain mcgrof@kernel.org +# +# This performs a series tests against the sysfs filesystem. + +# Kselftest framework requirement - SKIP code is 4. +ksft_skip=4 + +TEST_NAME="sysfs" +TEST_DRIVER="test_${TEST_NAME}" +TEST_DIR=$(dirname $0) +TEST_FILE=$(mktemp) + +# This represents +# +# TEST_ID:TEST_COUNT:ENABLED:TARGET +# +# TEST_ID: is the test id number +# TEST_COUNT: number of times we should run the test +# ENABLED: 1 if enabled, 0 otherwise +# TARGET: test target file required on the test_sysfs module +# +# Once these are enabled please leave them as-is. Write your own test, +# we have tons of space. +ALL_TESTS="0001:3:1:test_dev_x:misc" +ALL_TESTS="$ALL_TESTS 0002:3:1:test_dev_y:misc" +ALL_TESTS="$ALL_TESTS 0003:3:1:test_dev_x:misc" +ALL_TESTS="$ALL_TESTS 0004:3:1:test_dev_y:misc" +ALL_TESTS="$ALL_TESTS 0005:1:1:test_dev_x:misc" +ALL_TESTS="$ALL_TESTS 0006:1:1:test_dev_y:misc" +ALL_TESTS="$ALL_TESTS 0007:1:1:test_dev_y:misc" +ALL_TESTS="$ALL_TESTS 0008:1:1:test_dev_x:misc" +ALL_TESTS="$ALL_TESTS 0009:1:1:test_dev_y:misc" +ALL_TESTS="$ALL_TESTS 0010:1:1:test_dev_y:misc" +ALL_TESTS="$ALL_TESTS 0011:1:1:test_dev_x:misc" +ALL_TESTS="$ALL_TESTS 0012:1:1:test_dev_y:misc" +ALL_TESTS="$ALL_TESTS 0013:1:1:test_dev_y:misc" +ALL_TESTS="$ALL_TESTS 0014:3:1:test_dev_x:block" # block equivalent set +ALL_TESTS="$ALL_TESTS 0015:3:1:test_dev_x:block" +ALL_TESTS="$ALL_TESTS 0016:3:1:test_dev_x:block" +ALL_TESTS="$ALL_TESTS 0017:3:1:test_dev_y:block" +ALL_TESTS="$ALL_TESTS 0018:1:1:test_dev_x:block" +ALL_TESTS="$ALL_TESTS 0019:1:1:test_dev_y:block" +ALL_TESTS="$ALL_TESTS 0020:1:1:test_dev_y:block" +ALL_TESTS="$ALL_TESTS 0021:1:1:test_dev_x:block" +ALL_TESTS="$ALL_TESTS 0022:1:1:test_dev_y:block" +ALL_TESTS="$ALL_TESTS 0023:1:1:test_dev_y:block" +ALL_TESTS="$ALL_TESTS 0024:1:1:test_dev_x:block" +ALL_TESTS="$ALL_TESTS 0025:1:1:test_dev_y:block" +ALL_TESTS="$ALL_TESTS 0026:1:1:test_dev_y:block" +ALL_TESTS="$ALL_TESTS 0027:1:0:test_dev_x:block" # deadlock test +ALL_TESTS="$ALL_TESTS 0028:1:0:test_dev_x:block" # deadlock test with rntl_lock + +allow_user_defaults() +{ + if [ -z $DIR ]; then + case $TEST_DEV_TYPE in + misc) + DIR="/sys/devices/virtual/misc/${TEST_DRIVER}0" + ;; + block) + DIR="/sys/devices/virtual/block/${TEST_DRIVER}0" + ;; + *) + DIR="/sys/devices/virtual/misc/${TEST_DRIVER}0" + ;; + esac + fi + case $TEST_DEV_TYPE in + misc) + MODPROBE_TESTDEV_TYPE="" + ;; + block) + MODPROBE_TESTDEV_TYPE="devtype=1" + ;; + *) + MODPROBE_TESTDEV_TYPE="" + ;; + esac + if [ -z $SYSFS_DEBUGFS_DIR ]; then + SYSFS_DEBUGFS_DIR="/sys/kernel/debug/test_sysfs" + fi + if [ -z $PAGE_SIZE ]; then + PAGE_SIZE=$(getconf PAGESIZE) + fi + if [ -z $MAX_DIGITS ]; then + MAX_DIGITS=$(($PAGE_SIZE/8)) + fi + if [ -z $INT_MAX ]; then + INT_MAX=$(getconf INT_MAX) + fi + if [ -z $UINT_MAX ]; then + UINT_MAX=$(getconf UINT_MAX) + fi +} + +test_reqs() +{ + uid=$(id -u) + if [ $uid -ne 0 ]; then + echo $msg must be run as root >&2 + exit $ksft_skip + fi + + if ! which modprobe 2> /dev/null > /dev/null; then + echo "$0: You need modprobe installed" >&2 + exit $ksft_skip + fi + if ! which getconf 2> /dev/null > /dev/null; then + echo "$0: You need getconf installed" + exit $ksft_skip + fi + if ! which diff 2> /dev/null > /dev/null; then + echo "$0: You need diff installed" + exit $ksft_skip + fi + if ! which perl 2> /dev/null > /dev/null; then + echo "$0: You need perl installed" + exit $ksft_skip + fi +} + +call_modprobe() +{ + modprobe $TEST_DRIVER $MODPROBE_TESTDEV_TYPE $FIRST_MODPROBE_ARGS $MODPROBE_ARGS + return $? +} + +modprobe_reset() +{ + modprobe -q -r $TEST_DRIVER + call_modprobe + return $? +} + +modprobe_reset_enable_debugfs() +{ + FIRST_MODPROBE_ARGS="enable_debugfs=1" + modprobe_reset + unset FIRST_MODPROBE_ARGS +} + +modprobe_reset_enable_lock_on_rmmod() +{ + FIRST_MODPROBE_ARGS="enable_lock=1 enable_lock_on_rmmod=1 enable_verbose_writes=1" + modprobe_reset + unset FIRST_MODPROBE_ARGS +} + +modprobe_reset_enable_rtnl_lock_on_rmmod() +{ + FIRST_MODPROBE_ARGS="enable_lock=1 use_rtnl_lock=1 enable_lock_on_rmmod=1" + FIRST_MODPROBE_ARGS="$FIRST_MODPROBE_ARGS enable_verbose_writes=1" + modprobe_reset + unset FIRST_MODPROBE_ARGS +} + +load_req_mod() +{ + modprobe_reset + if [ ! -d $DIR ]; then + if ! modprobe -q -n $TEST_DRIVER; then + echo "$0: module $TEST_DRIVER not found [SKIP]" + echo "You must set CONFIG_TEST_SYSFS=m in your kernel" >&2 + exit $ksft_skip + fi + call_modprobe + if [ $? -ne 0 ]; then + echo "$0: modprobe $TEST_DRIVER failed." + exit + fi + fi +} + +config_reset() +{ + if ! echo -n "1" >"$DIR"/reset; then + echo "$0: reset should have worked" >&2 + exit 1 + fi +} + +debugfs_reset_first_test_dev_ignore_errors() +{ + echo -n "1" >"$SYSFS_DEBUGFS_DIR"/reset_first_test_dev +} + +set_orig() +{ + if [[ ! -z $TARGET ]] && [[ ! -z $ORIG ]]; then + if [ -f ${TARGET} ]; then + echo "${ORIG}" > "${TARGET}" + fi + fi +} + +set_test() +{ + echo "${TEST_STR}" > "${TARGET}" +} + +set_test_ignore_errors() +{ + echo "${TEST_STR}" > "${TARGET}" 2> /dev/null +} + +verify() +{ + local seen + seen=$(cat "$1") + target_short=$(basename $TARGET) + case $target_short in + test_dev_x) + if [ "${seen}" != "${TEST_STR}" ]; then + return 1 + fi + ;; + test_dev_y) + DIRNAME=$(dirname $1) + EXPECTED_RESULT="" + # If our target was the test file then what we write to it + # is the same as what that we expect when we read from it. + # When we write to test_dev_y directly though we expect + # a computed value which is driver specific. + if [[ "$DIRNAME" == "/tmp" ]]; then + let EXPECTED_RESULT="${TEST_STR}" + else + x=$(cat ${DIR}/test_dev_x) + let EXPECTED_RESULT="$x+${TEST_STR}+7" + fi + + if [[ "${seen}" != "${EXPECTED_RESULT}" ]]; then + return 1 + fi + ;; + *) + echo "Unsupported target type update test script: $target_short" + exit 1 + esac + return 0 +} + +verify_diff_w() +{ + echo "$TEST_STR" | diff -q -w -u - $1 > /dev/null + return $? +} + +test_rc() +{ + if [[ $rc != 0 ]]; then + echo "Failed test, return value: $rc" >&2 + exit $rc + fi +} + +test_finish() +{ + set_orig + rm -f "${TEST_FILE}" + + if [ ! -z ${old_strict} ]; then + echo ${old_strict} > ${WRITES_STRICT} + fi + exit $rc +} + +# kernfs requires us to write everything we want in one shot because +# There is no easy way for us to know if userspace is only doing a partial +# write, so we don't support them. We expect the entire buffer to come on +# the first write. If you're writing a value, first read the file, +# modify only the value you're changing, then write entire buffer back. +# Since we are only testing digits we just full single writes and old stuff. +# For more details, refer to kernfs_fop_write_iter(). +run_numerictests_single_write() +{ + echo "== Testing sysfs behavior against ${TARGET} ==" + + rc=0 + + echo -n "Writing test file ... " + echo "${TEST_STR}" > "${TEST_FILE}" + if ! verify "${TEST_FILE}"; then + echo "FAIL" >&2 + exit 1 + else + echo "ok" + fi + + echo -n "Checking the sysfs file is not set to test value ... " + if verify "${TARGET}"; then + echo "FAIL" >&2 + exit 1 + else + echo "ok" + fi + + echo -n "Writing to sysfs file from shell ... " + set_test + if ! verify "${TARGET}"; then + echo "FAIL" >&2 + exit 1 + else + echo "ok" + fi + + echo -n "Resetting sysfs file to original value ... " + set_orig + if verify "${TARGET}"; then + echo "FAIL" >&2 + exit 1 + else + echo "ok" + fi + + # Now that we've validated the sanity of "set_test" and "set_orig", + # we can use those functions to set starting states before running + # specific behavioral tests. + + echo -n "Writing to the entire sysfs file in a single write ... " + set_orig + dd if="${TEST_FILE}" of="${TARGET}" bs=4096 2>/dev/null + if ! verify "${TARGET}"; then + echo "FAIL" >&2 + rc=1 + else + echo "ok" + fi + + echo -n "Writing to the sysfs file with multiple long writes ... " + set_orig + (perl -e 'print "A" x 50;'; echo "${TEST_STR}") | \ + dd of="${TARGET}" bs=50 2>/dev/null + if verify "${TARGET}"; then + echo "FAIL" >&2 + rc=1 + else + echo "ok" + fi + test_rc +} + +reset_vals() +{ + echo -n 3 > $DIR/test_dev_x + echo -n 4 > $DIR/test_dev_x +} + +check_failure() +{ + echo -n "Testing that $1 fails as expected..." + reset_vals + TEST_STR="$1" + orig="$(cat $TARGET)" + echo -n "$TEST_STR" > $TARGET 2> /dev/null + + # write should fail and $TARGET should retain its original value + if [ $? = 0 ] || [ "$(cat $TARGET)" != "$orig" ]; then + echo "FAIL" >&2 + rc=1 + else + echo "ok" + fi + test_rc +} + +load_modreqs() +{ + export TEST_DEV_TYPE=$(get_test_type $1) + unset DIR + allow_user_defaults + load_req_mod +} + +target_exists() +{ + TARGET="${DIR}/$1" + TEST_ID="$2" + + if [ ! -f ${TARGET} ] ; then + echo "Target for test $TEST_ID: $TARGET does not exist, skipping test ..." + return 0 + fi + return 1 +} + +config_enable_lock() +{ + if ! echo -n 1 > $DIR/config_enable_lock; then + echo "$0: Unable to enable locks" >&2 + exit 1 + fi +} + +config_write_delay_msec_y() +{ + if ! echo -n $1 > $DIR/config_write_delay_msec_y ; then + echo "$0: Unable to set write_delay_msec_y to $1" >&2 + exit 1 + fi +} + +# Default filter for dmesg scanning. +# Ignore lockdep complaining about its own bugginess when scanning dmesg +# output, because we shouldn't be failing filesystem tests on account of +# lockdep. +_check_dmesg_filter() +{ + egrep -v -e "BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low" \ + -e "BUG: MAX_STACK_TRACE_ENTRIES too low" +} + +check_dmesg() +{ + # filter out intentional WARNINGs or Oopses + local filter=${1:-_check_dmesg_filter} + + _dmesg_since_test_start | $filter >$seqres.dmesg + egrep -q -e "kernel BUG at" \ + -e "WARNING:" \ + -e "\bBUG:" \ + -e "Oops:" \ + -e "possible recursive locking detected" \ + -e "Internal error" \ + -e "(INFO|ERR): suspicious RCU usage" \ + -e "INFO: possible circular locking dependency detected" \ + -e "general protection fault:" \ + -e "BUG .* remaining" \ + -e "UBSAN:" \ + $seqres.dmesg + if [ $? -eq 0 ]; then + echo "something found in dmesg (see $seqres.dmesg)" + return 1 + else + if [ "$KEEP_DMESG" != "yes" ]; then + rm -f $seqres.dmesg + fi + return 0 + fi +} + +log_kernel_fstest_dmesg() +{ + export FSTYP="$1" + export seqnum="$FSTYP/$2" + export date_time=$(date +"%F %T") + echo "run fstests $seqnum at $date_time" > /dev/kmsg +} + +modprobe_loop() +{ + while true; do + call_modprobe > /dev/null 2>&1 + modprobe -r $TEST_DRIVER > /dev/null 2>&1 + done > /dev/null 2>&1 +} + +write_loop() +{ + while true; do + set_test_ignore_errors > /dev/null 2>&1 + TEST_STR=$(( $TEST_STR + 1 )) + done > /dev/null 2>&1 +} + +write_loop_reset() +{ + while true; do + set_test_ignore_errors > /dev/null 2>&1 + debugfs_reset_first_test_dev_ignore_errors > /dev/null 2>&1 + done > /dev/null 2>&1 +} + +write_loop_bg() +{ + BG_WRITES=1000 > /dev/null 2>&1 + while true; do + for i in $(seq 1 $BG_WRITES); do + set_test_ignore_errors > /dev/null 2>&1 & + TEST_STR=$(( $TEST_STR + 1 )) + done > /dev/null 2>&1 + wait + done > /dev/null 2>&1 + wait +} + +reset_loop() +{ + while true; do + debugfs_reset_first_test_dev_ignore_errors > /dev/null 2>&1 + done > /dev/null 2>&1 +} + +kill_trigger_loop() +{ + + local my_first_loop_pid=$1 + local my_second_loop_pid=$2 + local my_sleep_max=$3 + local my_loop=0 + + while true; do + sleep 1 + if [[ $my_loop -ge $my_sleep_max ]]; then + break + fi + let my_loop=$my_loop+1 + done + + kill -s TERM $my_first_loop_pid 2>&1 > /dev/null + kill -s TERM $my_second_loop_pid 2>&1 > /dev/null +} + +_dmesg_since_test_start() +{ + # search the dmesg log of last run of $seqnum for possible failures + # use sed \cregexpc address type, since $seqnum contains "/" + dmesg | tac | sed -ne "0,#run fstests $seqnum at $date_time#p" | tac +} + +sysfs_test_0001() +{ + TARGET="${DIR}/$(get_test_target 0001)" + config_reset + reset_vals + ORIG=$(cat "${TARGET}") + TEST_STR=$(( $ORIG + 1 )) + + run_numerictests_single_write +} + +sysfs_test_0002() +{ + TARGET="${DIR}/$(get_test_target 0002)" + config_reset + ORIG=$(cat "${TARGET}") + TEST_STR=$(( $ORIG + 1 )) + + run_numerictests_single_write +} + +sysfs_test_0003() +{ + TARGET="${DIR}/$(get_test_target 0003)" + config_reset + ORIG=$(cat "${TARGET}") + TEST_STR=$(( $ORIG + 1 )) + + config_enable_lock + + run_numerictests_single_write +} + +sysfs_test_0004() +{ + TARGET="${DIR}/$(get_test_target 0004)" + config_reset + ORIG=$(cat "${TARGET}") + TEST_STR=$(( $ORIG + 1 )) + + config_enable_lock + + run_numerictests_single_write +} + +sysfs_test_0005() +{ + TARGET="${DIR}/$(get_test_target 0005)" + modprobe_reset + config_reset + ORIG=$(cat "${TARGET}") + TEST_STR=$(( $ORIG + 1 )) + WAIT_TIME=2 + + echo -n "Loop writing x while loading/unloading the module... " + + modprobe_loop & + modprobe_pid=$! + + write_loop & + write_pid=$! + + kill_trigger_loop $modprobe_pid $write_pid $WAIT_TIME > /dev/null 2>&1 & + kill_pid=$! + + wait $kill_pid > /dev/null 2>&1 + + if [[ $? -eq 0 ]]; then + echo "ok" + else + echo "FAIL" >&2 + fi +} + +sysfs_test_0006() +{ + TARGET="${DIR}/$(get_test_target 0006)" + modprobe_reset + config_reset + ORIG=$(cat "${TARGET}") + TEST_STR=$(( $ORIG + 1 )) + WAIT_TIME=2 + + echo -n "Loop writing y while loading/unloading the module... " + modprobe_loop & + modprobe_pid=$! + + write_loop & + write_pid=$! + + kill_trigger_loop $modprobe_pid $write_pid $WAIT_TIME > /dev/null 2>&1 & + kill_pid=$! + + wait $kill_pid > /dev/null 2>&1 + + if [[ $? -eq 0 ]]; then + echo "ok" + else + echo "FAIL" >&2 + fi +} + +sysfs_test_0007() +{ + TARGET="${DIR}/$(get_test_target 0007)" + modprobe_reset + config_reset + ORIG=$(cat "${TARGET}") + TEST_STR=$(( $ORIG + 1 )) + WAIT_TIME=2 + + echo -n "Loop writing y with a larger delay while loading/unloading the module... " + + MODPROBE_ARGS="write_delay_msec_y=1500" + modprobe_loop > /dev/null 2>&1 & + modprobe_pid=$! + unset MODPROBE_ARGS + + write_loop & + write_pid=$! + + kill_trigger_loop $modprobe_pid $write_pid $WAIT_TIME > /dev/null 2>&1 & + kill_pid=$! + + wait $kill_pid > /dev/null 2>&1 + + if [[ $? -eq 0 ]]; then + echo "ok" + else + echo "FAIL" >&2 + fi +} + +sysfs_test_0008() +{ + TARGET="${DIR}/$(get_test_target 0008)" + modprobe_reset + config_reset + reset_vals + ORIG=$(cat "${TARGET}") + TEST_STR=$(( $ORIG + 1 )) + WAIT_TIME=2 + + echo -n "Loop busy writing x while loading/unloading the module... " + + modprobe_loop > /dev/null 2>&1 & + modprobe_pid=$! + + write_loop_bg > /dev/null 2>&1 & + write_pid=$! + + kill_trigger_loop $modprobe_pid $write_pid $WAIT_TIME > /dev/null 2>&1 & + kill_pid=$! + + wait $kill_pid > /dev/null 2>&1 + + if [[ $? -eq 0 ]]; then + echo "ok" + else + echo "FAIL" >&2 + fi +} + +sysfs_test_0009() +{ + TARGET="${DIR}/$(get_test_target 0009)" + modprobe_reset + config_reset + reset_vals + ORIG=$(cat "${TARGET}") + TEST_STR=$(( $ORIG + 1 )) + WAIT_TIME=2 + + echo -n "Loop busy writing y while loading/unloading the module... " + + modprobe_loop > /dev/null 2>&1 & + modprobe_pid=$! + + write_loop_bg > /dev/null 2>&1 & + write_pid=$! + + kill_trigger_loop $modprobe_pid $write_pid $WAIT_TIME > /dev/null 2>&1 & + kill_pid=$! + + wait $kill_pid > /dev/null 2>&1 + + if [[ $? -eq 0 ]]; then + echo "ok" + else + echo "FAIL" >&2 + fi +} + +sysfs_test_0010() +{ + TARGET="${DIR}/$(get_test_target 0010)" + modprobe_reset + config_reset + reset_vals + ORIG=$(cat "${TARGET}") + TEST_STR=$(( $ORIG + 1 )) + WAIT_TIME=2 + + echo -n "Loop busy writing y with a larger delay while loading/unloading the module... " + modprobe -q -r $TEST_DRIVER > /dev/null 2>&1 + + MODPROBE_ARGS="write_delay_msec_y=1500" + modprobe_loop > /dev/null 2>&1 & + modprobe_pid=$! + unset MODPROBE_ARGS + + write_loop_bg > /dev/null 2>&1 & + write_pid=$! + + kill_trigger_loop $modprobe_pid $write_pid $WAIT_TIME > /dev/null 2>&1 & + kill_pid=$! + + wait $kill_pid > /dev/null 2>&1 + + if [[ $? -eq 0 ]]; then + echo "ok" + else + echo "FAIL" >&2 + fi +} + +sysfs_test_0011() +{ + TARGET="${DIR}/$(get_test_target 0011)" + modprobe_reset_enable_debugfs + config_reset + reset_vals + ORIG=$(cat "${TARGET}") + TEST_STR=$(( $ORIG + 1 )) + WAIT_TIME=2 + + echo -n "Loop writing x and resetting ... " + + write_loop > /dev/null 2>&1 & + write_pid=$! + + reset_loop > /dev/null 2>&1 & + reset_pid=$! + + kill_trigger_loop $write_pid $reset_pid $WAIT_TIME > /dev/null 2>&1 & + kill_pid=$! + + wait $kill_pid > /dev/null 2>&1 + + if [[ $? -eq 0 ]]; then + echo "ok" + else + echo "FAIL" >&2 + fi +} + +sysfs_test_0012() +{ + TARGET="${DIR}/$(get_test_target 0012)" + modprobe_reset_enable_debugfs + config_reset + reset_vals + ORIG=$(cat "${TARGET}") + TEST_STR=$(( $ORIG + 1 )) + WAIT_TIME=2 + + echo -n "Loop writing y and resetting ... " + + write_loop > /dev/null 2>&1 & + write_pid=$! + + reset_loop > /dev/null 2>&1 & + reset_pid=$! + + kill_trigger_loop $write_pid $reset_pid $WAIT_TIME > /dev/null 2>&1 & + kill_pid=$! + + wait $kill_pid > /dev/null 2>&1 + + if [[ $? -eq 0 ]]; then + echo "ok" + else + echo "FAIL" >&2 + fi +} + +sysfs_test_0013() +{ + TARGET="${DIR}/$(get_test_target 0013)" + modprobe_reset_enable_debugfs + config_reset + reset_vals + config_write_delay_msec_y 1500 + ORIG=$(cat "${TARGET}") + TEST_STR=$(( $ORIG + 1 )) + WAIT_TIME=2 + + echo -n "Loop writing y with a larger delay and resetting ... " + + write_loop > /dev/null 2>&1 & + write_pid=$! + + reset_loop > /dev/null 2>&1 & + reset_pid=$! + + kill_trigger_loop $write_pid $reset_pid $WAIT_TIME > /dev/null 2>&1 & + kill_pid=$! + + wait $kill_pid > /dev/null 2>&1 + + if [[ $? -eq 0 ]]; then + echo "ok" + else + echo "FAIL" >&2 + fi +} + +sysfs_test_0014() +{ + sysfs_test_0001 +} + +sysfs_test_0015() +{ + sysfs_test_0002 +} + +sysfs_test_0016() +{ + sysfs_test_0003 +} + +sysfs_test_0017() +{ + sysfs_test_0004 +} + +sysfs_test_0018() +{ + sysfs_test_0005 +} + +sysfs_test_0019() +{ + sysfs_test_0006 +} + +sysfs_test_0020() +{ + sysfs_test_0007 +} + +sysfs_test_0021() +{ + sysfs_test_0008 +} + +sysfs_test_0022() +{ + sysfs_test_0009 +} + +sysfs_test_0023() +{ + sysfs_test_0010 +} + +sysfs_test_0024() +{ + sysfs_test_0011 +} + +sysfs_test_0025() +{ + sysfs_test_0012 +} + +sysfs_test_0026() +{ + sysfs_test_0013 +} + +sysfs_test_0027() +{ + TARGET="${DIR}/$(get_test_target 0027)" + modprobe_reset_enable_lock_on_rmmod + ORIG=$(cat "${TARGET}") + TEST_STR=$(( $ORIG + 1 )) + WAIT_TIME=2 + + echo -n "Test for possible rmmod deadlock while writing x ... " + + write_loop > /dev/null 2>&1 & + write_pid=$! + + MODPROBE_ARGS="enable_lock=1 enable_lock_on_rmmod=1 enable_verbose_writes=1" + modprobe_loop > /dev/null 2>&1 & + modprobe_pid=$! + unset MODPROBE_ARGS + + kill_trigger_loop $modprobe_pid $write_pid $WAIT_TIME > /dev/null 2>&1 & + kill_pid=$! + + wait $kill_pid > /dev/null 2>&1 + + if [[ $? -eq 0 ]]; then + echo "ok" + else + echo "FAIL" >&2 + fi +} + +sysfs_test_0028() +{ + TARGET="${DIR}/$(get_test_target 0028)" + modprobe_reset_enable_lock_on_rmmod + ORIG=$(cat "${TARGET}") + TEST_STR=$(( $ORIG + 1 )) + WAIT_TIME=2 + + echo -n "Test for possible rmmod deadlock using rtnl_lock while writing x ... " + + write_loop > /dev/null 2>&1 & + write_pid=$! + + MODPROBE_ARGS="enable_lock=1 enable_lock_on_rmmod=1 use_rtnl_lock=1 enable_verbose_writes=1" + modprobe_loop > /dev/null 2>&1 & + modprobe_pid=$! + unset MODPROBE_ARGS + + kill_trigger_loop $modprobe_pid $write_pid $WAIT_TIME > /dev/null 2>&1 & + kill_pid=$! + + wait $kill_pid > /dev/null 2>&1 + + if [[ $? -eq 0 ]]; then + echo "ok" + else + echo "FAIL" >&2 + fi +} + +test_gen_desc() +{ + echo -n "$1 x $(get_test_count $1)" +} + +list_tests() +{ + echo "Test ID list:" + echo + echo "TEST_ID x NUM_TEST" + echo "TEST_ID: Test ID" + echo "NUM_TESTS: Number of recommended times to run the test" + echo + echo "$(test_gen_desc 0001) - misc test writing x in different ways" + echo "$(test_gen_desc 0002) - misc test writing y in different ways" + echo "$(test_gen_desc 0003) - misc test writing x in different ways using a mutex lock" + echo "$(test_gen_desc 0004) - misc test writing y in different ways using a mutex lock" + echo "$(test_gen_desc 0005) - misc test writing x load and remove the test_sysfs module" + echo "$(test_gen_desc 0006) - misc writing y load and remove the test_sysfs module" + echo "$(test_gen_desc 0007) - misc test writing y larger delay, load, remove test_sysfs" + echo "$(test_gen_desc 0008) - misc test busy writing x remove test_sysfs module" + echo "$(test_gen_desc 0009) - misc test busy writing y remove the test_sysfs module" + echo "$(test_gen_desc 0010) - misc test busy writing y larger delay, remove test_sysfs" + echo "$(test_gen_desc 0011) - misc test writing x and resetting device" + echo "$(test_gen_desc 0012) - misc test writing y and resetting device" + echo "$(test_gen_desc 0013) - misc test writing y with a larger delay and resetting device" + echo "$(test_gen_desc 0014) - block test writing x in different ways" + echo "$(test_gen_desc 0015) - block test writing y in different ways" + echo "$(test_gen_desc 0016) - block test writing x in different ways using a mutex lock" + echo "$(test_gen_desc 0017) - block test writing y in different ways using a mutex lock" + echo "$(test_gen_desc 0018) - block test writing x load and remove the test_sysfs module" + echo "$(test_gen_desc 0019) - block test writing y load and remove the test_sysfs module" + echo "$(test_gen_desc 0020) - block test writing y larger delay, load, remove test_sysfs" + echo "$(test_gen_desc 0021) - block test busy writing x remove the test_sysfs module" + echo "$(test_gen_desc 0022) - block test busy writing y remove the test_sysfs module" + echo "$(test_gen_desc 0023) - block test busy writing y larger delay, remove test_sysfs" + echo "$(test_gen_desc 0024) - block test writing x and resetting device" + echo "$(test_gen_desc 0025) - block test writing y and resetting device" + echo "$(test_gen_desc 0026) - block test writing y larger delay and resetting device" + echo "$(test_gen_desc 0027) - test rmmod deadlock while writing x ... " + echo "$(test_gen_desc 0028) - test rmmod deadlock using rtnl_lock while writing x ..." +} + +usage() +{ + NUM_TESTS=$(grep -o ' ' <<<"$ALL_TESTS" | grep -c .) + let NUM_TESTS=$NUM_TESTS+1 + MAX_TEST=$(printf "%04d\n" $NUM_TESTS) + echo "Usage: $0 [ -t <4-number-digit> ] | [ -w <4-number-digit> ] |" + echo " [ -s <4-number-digit> ] | [ -c <4-number-digit> <test- count>" + echo " [ all ] [ -h | --help ] [ -l ]" + echo "" + echo "Valid tests: 0001-$MAX_TEST" + echo "" + echo " all Runs all tests (default)" + echo " -t Run test ID the number amount of times is recommended" + echo " -w Watch test ID run until it runs into an error" + echo " -c Run test ID once" + echo " -s Run test ID x test-count number of times" + echo " -l List all test ID list" + echo " -h|--help Help" + echo + echo "If an error every occurs execution will immediately terminate." + echo "If you are adding a new test try using -w <test-ID> first to" + echo "make sure the test passes a series of tests." + echo + echo Example uses: + echo + echo "$TEST_NAME.sh -- executes all tests" + echo "$TEST_NAME.sh -t 0002 -- Executes test ID 0002 number of times is recomended" + echo "$TEST_NAME.sh -w 0002 -- Watch test ID 0002 run until an error occurs" + echo "$TEST_NAME.sh -s 0002 -- Run test ID 0002 once" + echo "$TEST_NAME.sh -c 0002 3 -- Run test ID 0002 three times" + echo + list_tests + exit 1 +} + +test_num() +{ + re='^[0-9]+$' + if ! [[ $1 =~ $re ]]; then + usage + fi +} + +get_test_count() +{ + test_num $1 + TEST_NUM=$(echo $1 | sed 's/^0*//') + TEST_DATA=$(echo $ALL_TESTS | awk '{print $'$TEST_NUM'}') + echo ${TEST_DATA} | awk -F":" '{print $2}' +} + +get_test_enabled() +{ + test_num $1 + TEST_NUM=$(echo $1 | sed 's/^0*//') + TEST_DATA=$(echo $ALL_TESTS | awk '{print $'$TEST_NUM'}') + echo ${TEST_DATA} | awk -F":" '{print $3}' +} + +get_test_target() +{ + test_num $1 + TEST_NUM=$(echo $1 | sed 's/^0*//') + TEST_DATA=$(echo $ALL_TESTS | awk '{print $'$TEST_NUM'}') + echo ${TEST_DATA} | awk -F":" '{print $4}' +} + +get_test_type() +{ + test_num $1 + TEST_NUM=$(echo $1 | sed 's/^0*//') + TEST_DATA=$(echo $ALL_TESTS | awk '{print $'$TEST_NUM'}') + echo ${TEST_DATA} | awk -F":" '{print $5}' +} + +run_all_tests() +{ + for i in $ALL_TESTS ; do + TEST_ID=$(echo $i | awk -F":" '{print $1}') + ENABLED=$(get_test_enabled $TEST_ID) + TEST_COUNT=$(get_test_count $TEST_ID) + TEST_TARGET=$(get_test_target $TEST_ID) + if [[ $ENABLED -eq "1" ]]; then + test_case $TEST_ID $TEST_COUNT $TEST_TARGET + else + echo -n "Skipping test $TEST_ID as its disabled, likely " + echo "could crash your system ..." + fi + done +} + +watch_log() +{ + if [ $# -ne 3 ]; then + clear + fi + echo "Running test: $2 - run #$1" +} + +watch_case() +{ + i=0 + while [ 1 ]; do + if [ $# -eq 1 ]; then + test_num $1 + watch_log $i ${TEST_NAME}_test_$1 + log_kernel_fstest_dmesg sysfs $1 + RUN_TEST=${TEST_NAME}_test_$1 + $RUN_TEST + check_dmesg + if [[ $? -ne 0 ]]; then + exit 1 + fi + else + watch_log $i all + run_all_tests + fi + let i=$i+1 + done +} + +test_case() +{ + NUM_TESTS=$2 + + i=0 + + load_modreqs $1 + if target_exists $3 $1; then + return + fi + + while [[ $i -lt $NUM_TESTS ]]; do + test_num $1 + watch_log $i ${TEST_NAME}_test_$1 noclear + log_kernel_fstest_dmesg sysfs $1 + RUN_TEST=${TEST_NAME}_test_$1 + $RUN_TEST + let i=$i+1 + done + check_dmesg + if [[ $? -ne 0 ]]; then + exit 1 + fi +} + +parse_args() +{ + if [ $# -eq 0 ]; then + run_all_tests + else + if [[ "$1" = "all" ]]; then + run_all_tests + elif [[ "$1" = "-w" ]]; then + shift + watch_case $@ + elif [[ "$1" = "-t" ]]; then + shift + test_num $1 + test_case $1 $(get_test_count $1) $(get_test_target $1) + shift + elif [[ "$1" = "-c" ]]; then + shift + test_num $1 + test_num $2 + test_case $1 $2 $(get_test_target $1) + shift + shift + elif [[ "$1" = "-s" ]]; then + shift + test_case $1 1 $(get_test_target $1) + shift + elif [[ "$1" = "-l" ]]; then + list_tests + shift + elif [[ "$1" = "-h" || "$1" = "--help" ]]; then + usage + else + usage + fi + fi +} + +test_reqs +allow_user_defaults + +trap "test_finish" EXIT + +parse_args $@ + +exit 0

This extends test_sysfs with support for using the failure injection wait completion and knobs to force a few race conditions which demonstrates that kernfs active reference protection is sufficient for kobject / device protection at higher layers.

This adds 4 new tests which tries to remove the device attribute store operation in 4 different situations:

1) at the start of kernfs_kernfs_fop_write_iter() 2) before the of->mutex is held in kernfs_kernfs_fop_write_iter() 3) after the of->mutex is held in kernfs_kernfs_fop_write_iter() 4) after the kernfs node active reference is taken with kernfs_get_active()

A write can fail or succeed before the kernfs node active reference is obtained with kernfs_get_active(), and the reason is that the del_gendisk() may happen before the write or after the write is triggered. However, regardless of the delayed used, all writes are gauranteed to succeed after kernfs_get_active(), and so del_gendisk() must wait for any pending writes to complete. The fact that you cannot remove the kernfs entry while the kenfs entry is active also implies that a module that created the respective sysfs / kernfs entry *cannot* be removed during a sysfs operation. Test number 32 provides us with proof of this. If it were not true test #32 should crash.

No null dereferences are reproduced, even though this has been observed in some complex testing cases [0]. If this issue really exists we should have enough tools on the sysfs_test toolbox now to try to reproduce this easily without having to poke around other drivers. It very likley was the case that the issue reported [0] was possibly a side issue after the first bug which was zram specific. This is why it is important to isolate the issue and try to reproduce it in a generic form using the test_sysfs driver.

[0] https://lkml.kernel.org/r/20210623215007.862787-1-mcgrof@kernel.org

Signed-off-by: Luis Chamberlain mcgrof@kernel.org --- lib/Kconfig.debug | 1 + lib/test_sysfs.c | 19 +++ tools/testing/selftests/sysfs/config | 3 + tools/testing/selftests/sysfs/sysfs.sh | 214 +++++++++++++++++++++++++ 4 files changed, 237 insertions(+)

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 04d2c3f53d2a..ab3052277f23 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -2359,6 +2359,7 @@ config TEST_SYSFS depends on SYSFS depends on NET depends on BLOCK + depends on FAIL_KERNFS_KNOBS help This builds the "test_sysfs" module. This driver enables to test the sysfs file system safely without affecting production knobs which diff --git a/lib/test_sysfs.c b/lib/test_sysfs.c index 2a6ec072da60..6918fddb1aed 100644 --- a/lib/test_sysfs.c +++ b/lib/test_sysfs.c @@ -25,6 +25,9 @@ #include <linux/rtnetlink.h> #include <linux/genhd.h> #include <linux/blkdev.h> +#include <linux/kernfs.h> + +MODULE_IMPORT_NS(KERNFS_DEBUG_PRIVATE);

static bool enable_lock; module_param(enable_lock, bool_enable_only, 0644); @@ -69,6 +72,11 @@ static bool enable_verbose_rmmod; module_param(enable_verbose_rmmod, bool_enable_only, 0644); MODULE_PARM_DESC(enable_verbose_rmmod, "enable verbose print messages on rmmod");

+static bool enable_completion_on_rmmod; +module_param(enable_completion_on_rmmod, bool_enable_only, 0644); +MODULE_PARM_DESC(enable_completion_on_rmmod, + "enable sending a kernfs completion on rmmod"); + static int sysfs_test_major;

/** @@ -251,6 +259,8 @@ static ssize_t config_show(struct device *dev, enable_debugfs ? "true" : "false"); len += sysfs_emit_at(buf, len, "enable_verbose_writes:\t%s\n", enable_verbose_writes ? "true" : "false"); + len += sysfs_emit_at(buf, len, "enable_completion_on_rmmod:\t%s\n", + enable_completion_on_rmmod ? "true" : "false");

test_dev_config_unlock(test_dev);

@@ -877,10 +887,19 @@ static int __init test_sysfs_init(void) } module_init(test_sysfs_init);

+/* The goal is to race our device removal with a pending kernfs -> store call */ +static void test_sysfs_kernfs_send_completion_rmmod(void) +{ + if (!enable_completion_on_rmmod) + return; + complete(&kernfs_debug_wait_completion); +} + static void __exit test_sysfs_exit(void) { if (enable_debugfs) debugfs_remove(debugfs_dir); + test_sysfs_kernfs_send_completion_rmmod(); if (delay_rmmod_ms) msleep(delay_rmmod_ms); unregister_test_dev_sysfs(first_test_dev); diff --git a/tools/testing/selftests/sysfs/config b/tools/testing/selftests/sysfs/config index 9196f452ecd5..2876a229f95b 100644 --- a/tools/testing/selftests/sysfs/config +++ b/tools/testing/selftests/sysfs/config @@ -1,2 +1,5 @@ CONFIG_SYSFS=m CONFIG_TEST_SYSFS=m +CONFIG_FAULT_INJECTION=y +CONFIG_FAULT_INJECTION_DEBUG_FS=y +CONFIG_FAIL_KERNFS_KNOBS=y diff --git a/tools/testing/selftests/sysfs/sysfs.sh b/tools/testing/selftests/sysfs/sysfs.sh index 802651d78427..84093ee653c6 100755 --- a/tools/testing/selftests/sysfs/sysfs.sh +++ b/tools/testing/selftests/sysfs/sysfs.sh @@ -51,6 +51,10 @@ ALL_TESTS="$ALL_TESTS 0025:1:1:test_dev_y:block" ALL_TESTS="$ALL_TESTS 0026:1:1:test_dev_y:block" ALL_TESTS="$ALL_TESTS 0027:1:0:test_dev_x:block" # deadlock test ALL_TESTS="$ALL_TESTS 0028:1:0:test_dev_x:block" # deadlock test with rntl_lock +ALL_TESTS="$ALL_TESTS 0029:1:1:test_dev_x:block" # kernfs race removal of store +ALL_TESTS="$ALL_TESTS 0030:1:1:test_dev_x:block" # kernfs race removal before mutex +ALL_TESTS="$ALL_TESTS 0031:1:1:test_dev_x:block" # kernfs race removal after mutex +ALL_TESTS="$ALL_TESTS 0032:1:1:test_dev_x:block" # kernfs race removal after active

allow_user_defaults() { @@ -81,6 +85,9 @@ allow_user_defaults() if [ -z $SYSFS_DEBUGFS_DIR ]; then SYSFS_DEBUGFS_DIR="/sys/kernel/debug/test_sysfs" fi + if [ -z $KERNFS_DEBUGFS_DIR ]; then + KERNFS_DEBUGFS_DIR="/sys/kernel/debug/fail_kernfs" + fi if [ -z $PAGE_SIZE ]; then PAGE_SIZE=$(getconf PAGESIZE) fi @@ -156,6 +163,14 @@ modprobe_reset_enable_rtnl_lock_on_rmmod() unset FIRST_MODPROBE_ARGS }

+modprobe_reset_enable_completion() +{ + FIRST_MODPROBE_ARGS="enable_completion_on_rmmod=1 enable_verbose_writes=1" + FIRST_MODPROBE_ARGS="$FIRST_MODPROBE_ARGS enable_verbose_rmmod=1 delay_rmmod_ms=0" + modprobe_reset + unset FIRST_MODPROBE_ARGS +} + load_req_mod() { modprobe_reset @@ -186,6 +201,63 @@ debugfs_reset_first_test_dev_ignore_errors() echo -n "1" >"$SYSFS_DEBUGFS_DIR"/reset_first_test_dev }

+debugfs_kernfs_kernfs_fop_write_iter_exists() +{ + KNOB_DIR="${KERNFS_DEBUGFS_DIR}/config_fail_kernfs_fop_write_iter" + if [[ ! -d $KNOB_DIR ]]; then + echo "kernfs debugfs does not exist $KNOB_DIR" + return 0; + fi + KNOB_DEBUGFS="${KERNFS_DEBUGFS_DIR}/fail_kernfs_fop_write_iter" + if [[ ! -d $KNOB_DEBUGFS ]]; then + echo -n "kernfs debugfs for coniguring fail_kernfs_fop_write_iter " + echo "does not exist $KNOB_DIR" + return 0; + fi + return 1 +} + +debugfs_kernfs_kernfs_fop_write_iter_set_fail_once() +{ + KNOB_DEBUGFS="${KERNFS_DEBUGFS_DIR}/fail_kernfs_fop_write_iter" + echo 1 > $KNOB_DEBUGFS/interval + echo 100 > $KNOB_DEBUGFS/probability + echo 0 > $KNOB_DEBUGFS/space + # Disable verbose messages on the kernel ring buffer which may + # confuse developers with a kernel panic. + echo 0 > $KNOB_DEBUGFS/verbose + + # Fail only once + echo 1 > $KNOB_DEBUGFS/times +} + +debugfs_kernfs_kernfs_fop_write_iter_set_fail_never() +{ + KNOB_DEBUGFS="${KERNFS_DEBUGFS_DIR}/fail_kernfs_fop_write_iter" + echo 0 > $KNOB_DEBUGFS/times +} + +debugfs_kernfs_set_wait_ms() +{ + SLEEP_AFTER_WAIT_MS="${KERNFS_DEBUGFS_DIR}/sleep_after_wait_ms" + echo $1 > $SLEEP_AFTER_WAIT_MS +} + +debugfs_kernfs_disable_wait_kernfs_fop_write_iter() +{ + ENABLE_WAIT_KNOB="${KERNFS_DEBUGFS_DIR}/config_fail_kernfs_fop_write_iter/wait_" + for KNOB in ${ENABLE_WAIT_KNOB}*; do + echo 0 > $KNOB + done +} + +debugfs_kernfs_enable_wait_kernfs_fop_write_iter() +{ + ENABLE_WAIT_KNOB="${KERNFS_DEBUGFS_DIR}/config_fail_kernfs_fop_write_iter/wait_$1" + echo -n "1" > $ENABLE_WAIT_KNOB + return $? +} + set_orig() { if [[ ! -z $TARGET ]] && [[ ! -z $ORIG ]]; then @@ -961,6 +1033,144 @@ sysfs_test_0028() fi }

+sysfs_race_kernfs_kernfs_fop_write_iter() +{ + TARGET="${DIR}/$(get_test_target $1)" + WAIT_AT=$2 + EXPECT_WRITE_RETURNS=$3 + MSDELAY=$4 + + modprobe_reset_enable_completion + ORIG=$(cat "${TARGET}") + TEST_STR=$(( $ORIG + 1 )) + + echo -n "Test racing removal of sysfs store op with kernfs $WAIT_AT ... " + + if debugfs_kernfs_kernfs_fop_write_iter_exists; then + echo -n "skipping test as CONFIG_FAIL_KERNFS_KNOBS " + echo " or CONFIG_FAULT_INJECTION_DEBUG_FS is disabled" + return $ksft_skip + fi + + # Allow for failing the kernfs_kernfs_fop_write_iter call once, + # we'll provide exact context shortly afterwards. + debugfs_kernfs_kernfs_fop_write_iter_set_fail_once + + # First disable all waits + debugfs_kernfs_disable_wait_kernfs_fop_write_iter + + # Enable a wait_for_completion(&kernfs_debug_wait_completion) at the + # specified location inside the kernfs_fop_write_iter() routine + debugfs_kernfs_enable_wait_kernfs_fop_write_iter $WAIT_AT + + # Configure kernfs so that after its wait_for_completion() it + # will msleep() this amount of time and schedule(). We figure this + # will be sufficient time to allow for our module removal to complete. + debugfs_kernfs_set_wait_ms $MSDELAY + + # Now we trigger a kernfs write op, which will run kernfs_fop_write_iter, + # but will wait until our driver sends a respective completion + set_test_ignore_errors & + write_pid=$! + + # At this point kernfs_fop_write_iter() hasn't run our op, its + # waiting for our completion at the specified time $WAIT_AT. + # We now remove our module which will send a + # complete(&kernfs_debug_wait_completion) right before we deregister + # our device and the sysfs device attributes are removed. + # + # After the completion is sent, the test_sysfs driver races with + # kernfs to do the device deregistration with the kernfs msleep + # and schedule(). This should mean we've forced trying to remove the + # module prior to allowing kernfs to run our store operation. If the + # race did happen we'll panic with a null dereference on the store op. + # + # If no race happens we should see no write operation triggered. + modprobe -r $TEST_DRIVER > /dev/null 2>&1 + + debugfs_kernfs_kernfs_fop_write_iter_set_fail_never + + wait $write_pid + + check_dmesg + if [[ $? -ne 0 ]]; then + echo "FAIL" >&2 + exit 1 + fi + + # In cases where a write *can* fail or succeed, we don't care + # about the return code of the write, we just care we don't crash + # the kernel. + if [[ "$EXPECT_WRITE_RETURNS" == "2" ]]; then + echo "ok" + return + fi + + if [[ $? -eq $EXPECT_WRITE_RETURNS ]]; then + echo "ok" + else + echo "FAIL" >&2 + fi +} + +# The test cases 0029-0032 race writes issued to sysfs files exposed by a +# disk against del_gendisk() which removes these sysfs files. Each test case +# forces the race to happen at different points in time where the kernfs is +# processing a write, before the sysfs op gets called. +# +# The writes races against different parts of the kernfs_fop_write_iter(). +# A completion is sent by the test_sysfs driver on driver removal before +# del_gendisk() is called so to *start* the race. The races vary by time, +# specified in milliseconds. +# +# So for example test case 0029 will force the function kernfs_fop_write_iter() +# to wait for completion *at the start* of that function. The completion is +# issued by the test_sysfs driver on driver removal right before del_gendisk() +# is called. However test_sysfs will also wait a configurable amount of +# milliseconds before having del_gendisk() run. A long delay should ensure the +# write completes. +# +# Test case 0030 will do the same but before mutex_lock(&of->mutex) is called +# on kernfs_fop_write_iter(). And so on. Writes are only expected to *always* +# succeed once kernfs_get_active() is called successfully. Before that a write +# could succeed or fail, it will depend on what gets preempted / scheduled, and +# so the only thing we can be sure of is we should not be crashing the kernel. +# Before kernfs_get_active(), if an excessively long delay is used, then +# del_gendisk() is expected to be delayed and so writes should work. +sysfs_test_0029() +{ + for delay in 0 2 4 8 16 32 64 128 246 512 1024; do + echo "Delay-after-completion before del_gendisk(): $delay ms" + sysfs_race_kernfs_kernfs_fop_write_iter 0029 at_start 2 $delay + done +} + +sysfs_test_0030() +{ + for delay in 0 2 4 8 16 32 64 128 246 512 1024; do + echo "Delay-after-completion before del_gendisk(): $delay ms" + sysfs_race_kernfs_kernfs_fop_write_iter 0030 before_mutex 2 $delay + done +} + +sysfs_test_0031() +{ + for delay in 0 2 4 8 16 32 64 128 246 512 1024; do + echo "Delay-after-completion before del_gendisk(): $delay ms" + sysfs_race_kernfs_kernfs_fop_write_iter 0031 after_mutex 2 $delay + done +} + +# A write only guaranteed to succeed *iff* a module removal happens *after* +# the kernfs active reference is obtained with kernfs_get_active(). +sysfs_test_0032() +{ + for delay in 0 2 4 8 16 32 64 128 246 512 1024; do + echo "Delay-after-completion before del_gendisk(): $delay ms" + sysfs_race_kernfs_kernfs_fop_write_iter 0032 after_active 0 $delay + done +} + test_gen_desc() { echo -n "$1 x $(get_test_count $1)" @@ -1002,6 +1212,10 @@ list_tests() echo "$(test_gen_desc 0026) - block test writing y larger delay and resetting device" echo "$(test_gen_desc 0027) - test rmmod deadlock while writing x ... " echo "$(test_gen_desc 0028) - test rmmod deadlock using rtnl_lock while writing x ..." + echo "$(test_gen_desc 0029) - racing removal of store op with kernfs at start" + echo "$(test_gen_desc 0030) - racing removal of store op with kernfs before mutex" + echo "$(test_gen_desc 0031) - racing removal of store op with kernfs after mutex" + echo "$(test_gen_desc 0032) - racing removal of store op with kernfs after active" }

usage()