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 --- fs/sysfs/dir.c | 161 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 161 insertions(+) create mode 100644 fs/sysfs/dir.c (limited to 'fs/sysfs/dir.c') diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c new file mode 100644 index 000000000..ffdcd4153 --- /dev/null +++ b/fs/sysfs/dir.c @@ -0,0 +1,161 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * fs/sysfs/dir.c - sysfs core and dir operation implementation + * + * Copyright (c) 2001-3 Patrick Mochel + * Copyright (c) 2007 SUSE Linux Products GmbH + * Copyright (c) 2007 Tejun Heo + * + * Please see Documentation/filesystems/sysfs.rst for more information. + */ + +#define pr_fmt(fmt) "sysfs: " fmt + +#include +#include +#include +#include "sysfs.h" + +DEFINE_SPINLOCK(sysfs_symlink_target_lock); + +void sysfs_warn_dup(struct kernfs_node *parent, const char *name) +{ + char *buf; + + buf = kzalloc(PATH_MAX, GFP_KERNEL); + if (buf) + kernfs_path(parent, buf, PATH_MAX); + + pr_warn("cannot create duplicate filename '%s/%s'\n", buf, name); + dump_stack(); + + kfree(buf); +} + +/** + * sysfs_create_dir_ns - create a directory for an object with a namespace tag + * @kobj: object we're creating directory for + * @ns: the namespace tag to use + */ +int sysfs_create_dir_ns(struct kobject *kobj, const struct ns_common *ns) +{ + struct kernfs_node *parent, *kn; + kuid_t uid; + kgid_t gid; + + if (WARN_ON(!kobj)) + return -EINVAL; + + if (kobj->parent) + parent = kobj->parent->sd; + else + parent = sysfs_root_kn; + + if (!parent) + return -ENOENT; + + kobject_get_ownership(kobj, &uid, &gid); + + kn = kernfs_create_dir_ns(parent, kobject_name(kobj), 0755, uid, gid, + kobj, ns); + if (IS_ERR(kn)) { + if (PTR_ERR(kn) == -EEXIST) + sysfs_warn_dup(parent, kobject_name(kobj)); + return PTR_ERR(kn); + } + + kobj->sd = kn; + return 0; +} + +/** + * sysfs_remove_dir - remove an object's directory. + * @kobj: object. + * + * The only thing special about this is that we remove any files in + * the directory before we remove the directory, and we've inlined + * what used to be sysfs_rmdir() below, instead of calling separately. + */ +void sysfs_remove_dir(struct kobject *kobj) +{ + struct kernfs_node *kn = kobj->sd; + + /* + * In general, kobject owner is responsible for ensuring removal + * doesn't race with other operations and sysfs doesn't provide any + * protection; however, when @kobj is used as a symlink target, the + * symlinking entity usually doesn't own @kobj and thus has no + * control over removal. @kobj->sd may be removed anytime + * and symlink code may end up dereferencing an already freed node. + * + * sysfs_symlink_target_lock synchronizes @kobj->sd + * disassociation against symlink operations so that symlink code + * can safely dereference @kobj->sd. + */ + spin_lock(&sysfs_symlink_target_lock); + kobj->sd = NULL; + spin_unlock(&sysfs_symlink_target_lock); + + if (kn) { + WARN_ON_ONCE(kernfs_type(kn) != KERNFS_DIR); + kernfs_remove(kn); + } +} + +int sysfs_rename_dir_ns(struct kobject *kobj, const char *new_name, + const struct ns_common *new_ns) +{ + struct kernfs_node *parent; + int ret; + + parent = kernfs_get_parent(kobj->sd); + ret = kernfs_rename_ns(kobj->sd, parent, new_name, new_ns); + kernfs_put(parent); + return ret; +} + +int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj, + const struct ns_common *new_ns) +{ + struct kernfs_node *kn = kobj->sd; + struct kernfs_node *new_parent; + + new_parent = new_parent_kobj && new_parent_kobj->sd ? + new_parent_kobj->sd : sysfs_root_kn; + + return kernfs_rename_ns(kn, new_parent, NULL, new_ns); +} + +/** + * sysfs_create_mount_point - create an always empty directory + * @parent_kobj: kobject that will contain this always empty directory + * @name: The name of the always empty directory to add + */ +int sysfs_create_mount_point(struct kobject *parent_kobj, const char *name) +{ + struct kernfs_node *kn, *parent = parent_kobj->sd; + + kn = kernfs_create_empty_dir(parent, name); + if (IS_ERR(kn)) { + if (PTR_ERR(kn) == -EEXIST) + sysfs_warn_dup(parent, name); + return PTR_ERR(kn); + } + + return 0; +} +EXPORT_SYMBOL_GPL(sysfs_create_mount_point); + +/** + * sysfs_remove_mount_point - remove an always empty directory. + * @parent_kobj: kobject that will contain this always empty directory + * @name: The name of the always empty directory to remove + * + */ +void sysfs_remove_mount_point(struct kobject *parent_kobj, const char *name) +{ + struct kernfs_node *parent = parent_kobj->sd; + + kernfs_remove_by_name_ns(parent, name, NULL); +} +EXPORT_SYMBOL_GPL(sysfs_remove_mount_point); -- cgit v1.3.1