From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- drivers/md/dm-sysfs.c | 145 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 145 insertions(+) create mode 100644 drivers/md/dm-sysfs.c (limited to 'drivers/md/dm-sysfs.c') diff --git a/drivers/md/dm-sysfs.c b/drivers/md/dm-sysfs.c new file mode 100644 index 000000000..22bc70923 --- /dev/null +++ b/drivers/md/dm-sysfs.c @@ -0,0 +1,145 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2008 Red Hat, Inc. All rights reserved. + * + * This file is released under the GPL. + */ + +#include +#include +#include "dm-core.h" +#include "dm-rq.h" + +struct dm_sysfs_attr { + struct attribute attr; + ssize_t (*show)(struct mapped_device *md, char *p); + ssize_t (*store)(struct mapped_device *md, const char *p, size_t count); +}; + +#define DM_ATTR_RO(_name) \ +struct dm_sysfs_attr dm_attr_##_name = \ + __ATTR(_name, 0444, dm_attr_##_name##_show, NULL) + +static ssize_t dm_attr_show(struct kobject *kobj, struct attribute *attr, + char *page) +{ + struct dm_sysfs_attr *dm_attr; + struct mapped_device *md; + ssize_t ret; + + dm_attr = container_of(attr, struct dm_sysfs_attr, attr); + if (!dm_attr->show) + return -EIO; + + md = dm_get_from_kobject(kobj); + if (!md) + return -EINVAL; + + ret = dm_attr->show(md, page); + dm_put(md); + + return ret; +} + +#define DM_ATTR_RW(_name) \ +struct dm_sysfs_attr dm_attr_##_name = \ + __ATTR(_name, 0644, dm_attr_##_name##_show, dm_attr_##_name##_store) + +static ssize_t dm_attr_store(struct kobject *kobj, struct attribute *attr, + const char *page, size_t count) +{ + struct dm_sysfs_attr *dm_attr; + struct mapped_device *md; + ssize_t ret; + + dm_attr = container_of(attr, struct dm_sysfs_attr, attr); + if (!dm_attr->store) + return -EIO; + + md = dm_get_from_kobject(kobj); + if (!md) + return -EINVAL; + + ret = dm_attr->store(md, page, count); + dm_put(md); + + return ret; +} + +static ssize_t dm_attr_name_show(struct mapped_device *md, char *buf) +{ + if (dm_copy_name_and_uuid(md, buf, NULL)) + return -EIO; + + strcat(buf, "\n"); + return strlen(buf); +} + +static ssize_t dm_attr_uuid_show(struct mapped_device *md, char *buf) +{ + if (dm_copy_name_and_uuid(md, NULL, buf)) + return -EIO; + + strcat(buf, "\n"); + return strlen(buf); +} + +static ssize_t dm_attr_suspended_show(struct mapped_device *md, char *buf) +{ + return sysfs_emit(buf, "%d\n", dm_suspended_md(md)); +} + +static ssize_t dm_attr_use_blk_mq_show(struct mapped_device *md, char *buf) +{ + /* Purely for userspace compatibility */ + return sysfs_emit(buf, "%d\n", true); +} + +static DM_ATTR_RO(name); +static DM_ATTR_RO(uuid); +static DM_ATTR_RO(suspended); +static DM_ATTR_RO(use_blk_mq); +static DM_ATTR_RW(rq_based_seq_io_merge_deadline); + +static struct attribute *dm_attrs[] = { + &dm_attr_name.attr, + &dm_attr_uuid.attr, + &dm_attr_suspended.attr, + &dm_attr_use_blk_mq.attr, + &dm_attr_rq_based_seq_io_merge_deadline.attr, + NULL, +}; +ATTRIBUTE_GROUPS(dm); + +static const struct sysfs_ops dm_sysfs_ops = { + .show = dm_attr_show, + .store = dm_attr_store, +}; + +static const struct kobj_type dm_ktype = { + .sysfs_ops = &dm_sysfs_ops, + .default_groups = dm_groups, + .release = dm_kobject_release, +}; + +/* + * Initialize kobj + * because nobody using md yet, no need to call explicit dm_get/put + */ +int dm_sysfs_init(struct mapped_device *md) +{ + return kobject_init_and_add(dm_kobject(md), &dm_ktype, + &disk_to_dev(dm_disk(md))->kobj, + "%s", "dm"); +} + +/* + * Remove kobj, called after all references removed + */ +void dm_sysfs_exit(struct mapped_device *md) +{ + struct kobject *kobj = dm_kobject(md); + + kobject_put(kobj); + wait_for_completion(dm_get_completion_from_kobject(kobj)); +} -- cgit v1.3.1