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/configfs/mount.c | 179 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 179 insertions(+) create mode 100644 fs/configfs/mount.c (limited to 'fs/configfs/mount.c') diff --git a/fs/configfs/mount.c b/fs/configfs/mount.c new file mode 100644 index 000000000..4929f3431 --- /dev/null +++ b/fs/configfs/mount.c @@ -0,0 +1,179 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * mount.c - operations for initializing and mounting configfs. + * + * Based on sysfs: + * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel + * + * configfs Copyright (C) 2005 Oracle. All rights reserved. + */ + +#include +#include +#include +#include +#include +#include +#include + +#include +#include "configfs_internal.h" + +/* Random magic number */ +#define CONFIGFS_MAGIC 0x62656570 + +static struct vfsmount *configfs_mount = NULL; +struct kmem_cache *configfs_dir_cachep; +static int configfs_mnt_count = 0; + + +static void configfs_free_inode(struct inode *inode) +{ + if (S_ISLNK(inode->i_mode)) + kfree(inode->i_link); + free_inode_nonrcu(inode); +} + +static const struct super_operations configfs_ops = { + .statfs = simple_statfs, + .drop_inode = inode_just_drop, + .free_inode = configfs_free_inode, +}; + +static struct config_group configfs_root_group = { + .cg_item = { + .ci_namebuf = "root", + .ci_name = configfs_root_group.cg_item.ci_namebuf, + }, +}; + +int configfs_is_root(struct config_item *item) +{ + return item == &configfs_root_group.cg_item; +} + +static struct configfs_dirent configfs_root = { + .s_sibling = LIST_HEAD_INIT(configfs_root.s_sibling), + .s_children = LIST_HEAD_INIT(configfs_root.s_children), + .s_element = &configfs_root_group.cg_item, + .s_type = CONFIGFS_ROOT, + .s_iattr = NULL, +}; + +static int configfs_fill_super(struct super_block *sb, struct fs_context *fc) +{ + struct inode *inode; + struct dentry *root; + + sb->s_blocksize = PAGE_SIZE; + sb->s_blocksize_bits = PAGE_SHIFT; + sb->s_magic = CONFIGFS_MAGIC; + sb->s_op = &configfs_ops; + sb->s_time_gran = 1; + + inode = configfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO, + &configfs_root, sb); + if (inode) { + inode->i_op = &configfs_root_inode_operations; + inode->i_fop = &configfs_dir_operations; + /* directory inodes start off with i_nlink == 2 (for "." entry) */ + inc_nlink(inode); + } else { + pr_debug("could not get root inode\n"); + return -ENOMEM; + } + + root = d_make_root(inode); + if (!root) { + pr_debug("%s: could not get root dentry!\n",__func__); + return -ENOMEM; + } + config_group_init(&configfs_root_group); + configfs_root_group.cg_item.ci_dentry = root; + root->d_fsdata = &configfs_root; + sb->s_root = root; + set_default_d_op(sb, &configfs_dentry_ops); /* the rest get that */ + sb->s_d_flags |= DCACHE_DONTCACHE; + return 0; +} + +static int configfs_get_tree(struct fs_context *fc) +{ + return get_tree_single(fc, configfs_fill_super); +} + +static const struct fs_context_operations configfs_context_ops = { + .get_tree = configfs_get_tree, +}; + +static int configfs_init_fs_context(struct fs_context *fc) +{ + fc->ops = &configfs_context_ops; + return 0; +} + +static struct file_system_type configfs_fs_type = { + .owner = THIS_MODULE, + .name = "configfs", + .init_fs_context = configfs_init_fs_context, + .kill_sb = kill_anon_super, +}; +MODULE_ALIAS_FS("configfs"); + +struct dentry *configfs_pin_fs(void) +{ + int err = simple_pin_fs(&configfs_fs_type, &configfs_mount, + &configfs_mnt_count); + return err ? ERR_PTR(err) : configfs_mount->mnt_root; +} + +void configfs_release_fs(void) +{ + simple_release_fs(&configfs_mount, &configfs_mnt_count); +} + + +static int __init configfs_init(void) +{ + int err = -ENOMEM; + + configfs_dir_cachep = kmem_cache_create("configfs_dir_cache", + sizeof(struct configfs_dirent), + 0, 0, NULL); + if (!configfs_dir_cachep) + goto out; + + err = sysfs_create_mount_point(kernel_kobj, "config"); + if (err) + goto out2; + + err = register_filesystem(&configfs_fs_type); + if (err) + goto out3; + + return 0; +out3: + pr_err("Unable to register filesystem!\n"); + sysfs_remove_mount_point(kernel_kobj, "config"); +out2: + kmem_cache_destroy(configfs_dir_cachep); + configfs_dir_cachep = NULL; +out: + return err; +} + +static void __exit configfs_exit(void) +{ + unregister_filesystem(&configfs_fs_type); + sysfs_remove_mount_point(kernel_kobj, "config"); + kmem_cache_destroy(configfs_dir_cachep); + configfs_dir_cachep = NULL; +} + +MODULE_AUTHOR("Oracle"); +MODULE_LICENSE("GPL"); +MODULE_VERSION("0.0.2"); +MODULE_DESCRIPTION("Simple RAM filesystem for user driven kernel subsystem configuration."); + +core_initcall(configfs_init); +module_exit(configfs_exit); -- cgit v1.3.1