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/minix/dir.c | 458 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 458 insertions(+) create mode 100644 fs/minix/dir.c (limited to 'fs/minix/dir.c') diff --git a/fs/minix/dir.c b/fs/minix/dir.c new file mode 100644 index 000000000..2ca16f849 --- /dev/null +++ b/fs/minix/dir.c @@ -0,0 +1,458 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * linux/fs/minix/dir.c + * + * Copyright (C) 1991, 1992 Linus Torvalds + * + * minix directory handling functions + * + * Updated to filesystem version 3 by Daniel Aragones + */ + +#include "minix.h" +#include +#include +#include + +typedef struct minix_dir_entry minix_dirent; +typedef struct minix3_dir_entry minix3_dirent; + +static int minix_readdir(struct file *, struct dir_context *); + +const struct file_operations minix_dir_operations = { + .llseek = generic_file_llseek, + .read = generic_read_dir, + .iterate_shared = minix_readdir, + .fsync = simple_fsync, +}; + +/* + * Return the offset into page `page_nr' of the last valid + * byte in that page, plus one. + */ +static unsigned +minix_last_byte(struct inode *inode, unsigned long page_nr) +{ + unsigned last_byte = PAGE_SIZE; + + if (page_nr == (inode->i_size >> PAGE_SHIFT)) + last_byte = inode->i_size & (PAGE_SIZE - 1); + return last_byte; +} + +static void dir_commit_chunk(struct folio *folio, loff_t pos, unsigned len) +{ + struct address_space *mapping = folio->mapping; + struct inode *dir = mapping->host; + + block_write_end(pos, len, len, folio); + + if (pos+len > dir->i_size) { + i_size_write(dir, pos+len); + mark_inode_dirty(dir); + } + folio_unlock(folio); +} + +static int minix_handle_dirsync(struct inode *dir) +{ + int err; + + err = filemap_write_and_wait(dir->i_mapping); + if (!err) + err = sync_inode_metadata(dir, 1); + return err; +} + +static void *dir_get_folio(struct inode *dir, unsigned long n, + struct folio **foliop) +{ + struct folio *folio = read_mapping_folio(dir->i_mapping, n, NULL); + + if (IS_ERR(folio)) + return ERR_CAST(folio); + *foliop = folio; + return kmap_local_folio(folio, 0); +} + +static inline void *minix_next_entry(void *de, struct minix_sb_info *sbi) +{ + return (void*)((char*)de + sbi->s_dirsize); +} + +static int minix_readdir(struct file *file, struct dir_context *ctx) +{ + struct inode *inode = file_inode(file); + struct super_block *sb = inode->i_sb; + struct minix_sb_info *sbi = minix_sb(sb); + unsigned chunk_size = sbi->s_dirsize; + unsigned long npages = dir_pages(inode); + unsigned long pos = ctx->pos; + unsigned offset; + unsigned long n; + + ctx->pos = pos = ALIGN(pos, chunk_size); + if (pos >= inode->i_size) + return 0; + + offset = pos & ~PAGE_MASK; + n = pos >> PAGE_SHIFT; + + for ( ; n < npages; n++, offset = 0) { + char *p, *kaddr, *limit; + struct folio *folio; + + kaddr = dir_get_folio(inode, n, &folio); + if (IS_ERR(kaddr)) + continue; + p = kaddr+offset; + limit = kaddr + minix_last_byte(inode, n) - chunk_size; + for ( ; p <= limit; p = minix_next_entry(p, sbi)) { + const char *name; + __u32 inumber; + if (sbi->s_version == MINIX_V3) { + minix3_dirent *de3 = (minix3_dirent *)p; + name = de3->name; + inumber = de3->inode; + } else { + minix_dirent *de = (minix_dirent *)p; + name = de->name; + inumber = de->inode; + } + if (inumber) { + unsigned l = strnlen(name, sbi->s_namelen); + if (!dir_emit(ctx, name, l, + inumber, DT_UNKNOWN)) { + folio_release_kmap(folio, p); + return 0; + } + } + ctx->pos += chunk_size; + } + folio_release_kmap(folio, kaddr); + } + return 0; +} + +static inline int namecompare(int len, int maxlen, + const char * name, const char * buffer) +{ + if (len < maxlen && buffer[len]) + return 0; + return !memcmp(name, buffer, len); +} + +/* + * minix_find_entry() + * + * finds an entry in the specified directory with the wanted name. + * It does NOT read the inode of the + * entry - you'll have to do that yourself if you want to. + * + * On Success folio_release_kmap() should be called on *foliop. + */ +minix_dirent *minix_find_entry(struct dentry *dentry, struct folio **foliop) +{ + const char * name = dentry->d_name.name; + int namelen = dentry->d_name.len; + struct inode * dir = d_inode(dentry->d_parent); + struct super_block * sb = dir->i_sb; + struct minix_sb_info * sbi = minix_sb(sb); + unsigned long n; + unsigned long npages = dir_pages(dir); + char *p; + + char *namx; + __u32 inumber; + + for (n = 0; n < npages; n++) { + char *kaddr, *limit; + + kaddr = dir_get_folio(dir, n, foliop); + if (IS_ERR(kaddr)) + continue; + + limit = kaddr + minix_last_byte(dir, n) - sbi->s_dirsize; + for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) { + if (sbi->s_version == MINIX_V3) { + minix3_dirent *de3 = (minix3_dirent *)p; + namx = de3->name; + inumber = de3->inode; + } else { + minix_dirent *de = (minix_dirent *)p; + namx = de->name; + inumber = de->inode; + } + if (!inumber) + continue; + if (namecompare(namelen, sbi->s_namelen, name, namx)) + goto found; + } + folio_release_kmap(*foliop, kaddr); + } + return NULL; + +found: + return (minix_dirent *)p; +} + +int minix_add_link(struct dentry *dentry, struct inode *inode) +{ + struct inode *dir = d_inode(dentry->d_parent); + const char * name = dentry->d_name.name; + int namelen = dentry->d_name.len; + struct super_block * sb = dir->i_sb; + struct minix_sb_info * sbi = minix_sb(sb); + struct folio *folio = NULL; + unsigned long npages = dir_pages(dir); + unsigned long n; + char *kaddr, *p; + minix_dirent *de; + minix3_dirent *de3; + loff_t pos; + int err; + char *namx = NULL; + __u32 inumber; + + /* + * We take care of directory expansion in the same loop + * This code plays outside i_size, so it locks the page + * to protect that region. + */ + for (n = 0; n <= npages; n++) { + char *limit, *dir_end; + + kaddr = dir_get_folio(dir, n, &folio); + if (IS_ERR(kaddr)) + return PTR_ERR(kaddr); + folio_lock(folio); + dir_end = kaddr + minix_last_byte(dir, n); + limit = kaddr + PAGE_SIZE - sbi->s_dirsize; + for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) { + de = (minix_dirent *)p; + de3 = (minix3_dirent *)p; + if (sbi->s_version == MINIX_V3) { + namx = de3->name; + inumber = de3->inode; + } else { + namx = de->name; + inumber = de->inode; + } + if (p == dir_end) { + /* We hit i_size */ + if (sbi->s_version == MINIX_V3) + de3->inode = 0; + else + de->inode = 0; + goto got_it; + } + if (!inumber) + goto got_it; + err = -EEXIST; + if (namecompare(namelen, sbi->s_namelen, name, namx)) + goto out_unlock; + } + folio_unlock(folio); + folio_release_kmap(folio, kaddr); + } + BUG(); + return -EINVAL; + +got_it: + pos = folio_pos(folio) + offset_in_folio(folio, p); + err = minix_prepare_chunk(folio, pos, sbi->s_dirsize); + if (err) + goto out_unlock; + memcpy (namx, name, namelen); + if (sbi->s_version == MINIX_V3) { + memset (namx + namelen, 0, sbi->s_dirsize - namelen - 4); + de3->inode = inode->i_ino; + } else { + memset (namx + namelen, 0, sbi->s_dirsize - namelen - 2); + de->inode = inode->i_ino; + } + dir_commit_chunk(folio, pos, sbi->s_dirsize); + inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir)); + mark_inode_dirty(dir); + err = minix_handle_dirsync(dir); +out_put: + folio_release_kmap(folio, kaddr); + return err; +out_unlock: + folio_unlock(folio); + goto out_put; +} + +int minix_delete_entry(struct minix_dir_entry *de, struct folio *folio) +{ + struct inode *inode = folio->mapping->host; + loff_t pos = folio_pos(folio) + offset_in_folio(folio, de); + struct minix_sb_info *sbi = minix_sb(inode->i_sb); + unsigned len = sbi->s_dirsize; + int err; + + folio_lock(folio); + err = minix_prepare_chunk(folio, pos, len); + if (err) { + folio_unlock(folio); + return err; + } + if (sbi->s_version == MINIX_V3) + ((minix3_dirent *)de)->inode = 0; + else + de->inode = 0; + dir_commit_chunk(folio, pos, len); + inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode)); + mark_inode_dirty(inode); + return minix_handle_dirsync(inode); +} + +int minix_make_empty(struct inode *inode, struct inode *dir) +{ + struct folio *folio = filemap_grab_folio(inode->i_mapping, 0); + struct minix_sb_info *sbi = minix_sb(inode->i_sb); + char *kaddr; + int err; + + if (IS_ERR(folio)) + return PTR_ERR(folio); + err = minix_prepare_chunk(folio, 0, 2 * sbi->s_dirsize); + if (err) { + folio_unlock(folio); + goto fail; + } + + kaddr = kmap_local_folio(folio, 0); + memset(kaddr, 0, folio_size(folio)); + + if (sbi->s_version == MINIX_V3) { + minix3_dirent *de3 = (minix3_dirent *)kaddr; + + de3->inode = inode->i_ino; + strcpy(de3->name, "."); + de3 = minix_next_entry(de3, sbi); + de3->inode = dir->i_ino; + strcpy(de3->name, ".."); + } else { + minix_dirent *de = (minix_dirent *)kaddr; + + de->inode = inode->i_ino; + strcpy(de->name, "."); + de = minix_next_entry(de, sbi); + de->inode = dir->i_ino; + strcpy(de->name, ".."); + } + kunmap_local(kaddr); + + dir_commit_chunk(folio, 0, 2 * sbi->s_dirsize); + err = minix_handle_dirsync(inode); +fail: + folio_put(folio); + return err; +} + +/* + * routine to check that the specified directory is empty (for rmdir) + */ +int minix_empty_dir(struct inode * inode) +{ + struct folio *folio = NULL; + unsigned long i, npages = dir_pages(inode); + struct minix_sb_info *sbi = minix_sb(inode->i_sb); + char *name, *kaddr; + __u32 inumber; + + for (i = 0; i < npages; i++) { + char *p, *limit; + + kaddr = dir_get_folio(inode, i, &folio); + if (IS_ERR(kaddr)) + continue; + + limit = kaddr + minix_last_byte(inode, i) - sbi->s_dirsize; + for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) { + if (sbi->s_version == MINIX_V3) { + minix3_dirent *de3 = (minix3_dirent *)p; + name = de3->name; + inumber = de3->inode; + } else { + minix_dirent *de = (minix_dirent *)p; + name = de->name; + inumber = de->inode; + } + + if (inumber != 0) { + /* check for . and .. */ + if (name[0] != '.') + goto not_empty; + if (!name[1]) { + if (inumber != inode->i_ino) + goto not_empty; + } else if (name[1] != '.') + goto not_empty; + else if (name[2]) + goto not_empty; + } + } + folio_release_kmap(folio, kaddr); + } + return 1; + +not_empty: + folio_release_kmap(folio, kaddr); + return 0; +} + +/* Releases the page */ +int minix_set_link(struct minix_dir_entry *de, struct folio *folio, + struct inode *inode) +{ + struct inode *dir = folio->mapping->host; + struct minix_sb_info *sbi = minix_sb(dir->i_sb); + loff_t pos = folio_pos(folio) + offset_in_folio(folio, de); + int err; + + folio_lock(folio); + err = minix_prepare_chunk(folio, pos, sbi->s_dirsize); + if (err) { + folio_unlock(folio); + return err; + } + if (sbi->s_version == MINIX_V3) + ((minix3_dirent *)de)->inode = inode->i_ino; + else + de->inode = inode->i_ino; + dir_commit_chunk(folio, pos, sbi->s_dirsize); + inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir)); + mark_inode_dirty(dir); + return minix_handle_dirsync(dir); +} + +struct minix_dir_entry *minix_dotdot(struct inode *dir, struct folio **foliop) +{ + struct minix_sb_info *sbi = minix_sb(dir->i_sb); + struct minix_dir_entry *de = dir_get_folio(dir, 0, foliop); + + if (!IS_ERR(de)) + return minix_next_entry(de, sbi); + return NULL; +} + +ino_t minix_inode_by_name(struct dentry *dentry) +{ + struct folio *folio; + struct minix_dir_entry *de = minix_find_entry(dentry, &folio); + ino_t res = 0; + + if (de) { + struct inode *inode = folio->mapping->host; + struct minix_sb_info *sbi = minix_sb(inode->i_sb); + + if (sbi->s_version == MINIX_V3) + res = ((minix3_dirent *) de)->inode; + else + res = de->inode; + folio_release_kmap(folio, de); + } + return res; +} -- cgit v1.3.1