ftrace: Synchronize the initialization of ftrace_opsgrafted

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 <rostedt@goodmis.org>

1 files changed, 280 insertions, 0 deletions

diff --git a/fs/isofs/dir.c b/fs/isofs/dir.c
new file mode 100644
index 000000000..c7ca7603e
--- /dev/null
+++ b/fs/isofs/dir.c
@@ -0,0 +1,280 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  linux/fs/isofs/dir.c
+ *
+ *  (C) 1992, 1993, 1994  Eric Youngdale Modified for ISO 9660 filesystem.
+ *
+ *  (C) 1991  Linus Torvalds - minix filesystem
+ *
+ *  Steve Beynon		       : Missing last directory entries fixed
+ *  (stephen@askone.demon.co.uk)      : 21st June 1996
+ *
+ *  isofs directory handling functions
+ */
+#include <linux/gfp.h>
+#include <linux/filelock.h>
+#include <linux/slab.h>
+#include "isofs.h"
+#include <linux/fileattr.h>
+
+int isofs_name_translate(struct iso_directory_record *de, char *new, struct inode *inode)
+{
+	char * old = de->name;
+	int len = de->name_len[0];
+	int i;
+
+	for (i = 0; i < len; i++) {
+		unsigned char c = old[i];
+		if (!c)
+			break;
+
+		if (c >= 'A' && c <= 'Z')
+			c |= 0x20;	/* lower case */
+
+		/* Drop trailing '.;1' (ISO 9660:1988 7.5.1 requires period) */
+		if (c == '.' && i == len - 3 && old[i + 1] == ';' && old[i + 2] == '1')
+			break;
+
+		/* Drop trailing ';1' */
+		if (c == ';' && i == len - 2 && old[i + 1] == '1')
+			break;
+
+		/* Convert remaining ';' to '.' */
+		/* Also '/' to '.' (broken Acorn-generated ISO9660 images) */
+		if (c == ';' || c == '/')
+			c = '.';
+
+		new[i] = c;
+	}
+	return i;
+}
+
+/* Acorn extensions written by Matthew Wilcox <willy@infradead.org> 1998 */
+int get_acorn_filename(struct iso_directory_record *de,
+			    char *retname, struct inode *inode)
+{
+	int std;
+	unsigned char *chr;
+	int retnamlen = isofs_name_translate(de, retname, inode);
+
+	if (retnamlen == 0)
+		return 0;
+	std = sizeof(struct iso_directory_record) + de->name_len[0];
+	if (std & 1)
+		std++;
+	if (de->length[0] - std != 32)
+		return retnamlen;
+	chr = ((unsigned char *) de) + std;
+	if (strncmp(chr, "ARCHIMEDES", 10))
+		return retnamlen;
+	if ((*retname == '_') && ((chr[19] & 1) == 1))
+		*retname = '!';
+	if (((de->flags[0] & 2) == 0) && (chr[13] == 0xff)
+		&& ((chr[12] & 0xf0) == 0xf0)) {
+		retname[retnamlen] = ',';
+		sprintf(retname+retnamlen+1, "%3.3x",
+			((chr[12] & 0xf) << 8) | chr[11]);
+		retnamlen += 4;
+	}
+	return retnamlen;
+}
+
+/*
+ * This should _really_ be cleaned up some day..
+ */
+static int do_isofs_readdir(struct inode *inode, struct file *file,
+		struct dir_context *ctx,
+		char *tmpname)
+{
+	unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
+	unsigned char bufbits = ISOFS_BUFFER_BITS(inode);
+	unsigned long block, offset, block_saved, offset_saved;
+	unsigned long inode_number = 0;	/* Quiet GCC */
+	struct buffer_head *bh = NULL;
+	int len;
+	int map;
+	int first_de = 1;
+	char *p = NULL;		/* Quiet GCC */
+	struct iso_directory_record *de;
+	struct isofs_sb_info *sbi = ISOFS_SB(inode->i_sb);
+
+	offset = ctx->pos & (bufsize - 1);
+	block = ctx->pos >> bufbits;
+
+	while (ctx->pos < inode->i_size) {
+		int de_len;
+
+		if (!bh) {
+			bh = isofs_bread(inode, block);
+			if (!bh)
+				return 0;
+		}
+
+		de = (struct iso_directory_record *) (bh->b_data + offset);
+
+		de_len = *(unsigned char *)de;
+
+		/*
+		 * If the length byte is zero, we should move on to the next
+		 * CDROM sector.  If we are at the end of the directory, we
+		 * kick out of the while loop.
+		 */
+
+		if (de_len == 0) {
+			brelse(bh);
+			bh = NULL;
+			ctx->pos = (ctx->pos + ISOFS_BLOCK_SIZE) & ~(ISOFS_BLOCK_SIZE - 1);
+			block = ctx->pos >> bufbits;
+			offset = 0;
+			continue;
+		}
+
+		block_saved = block;
+		offset_saved = offset;
+		offset += de_len;
+
+		if (!isofs_dir_record_valid(de, offset_saved, bufsize)) {
+			printk(KERN_NOTICE "iso9660: Corrupted directory entry"
+			       " in block %lu of inode %llu\n", block,
+			       inode->i_ino);
+			brelse(bh);
+			return -EIO;
+		}
+
+		if (first_de) {
+			isofs_normalize_block_and_offset(de,
+							&block_saved,
+							&offset_saved);
+			inode_number = isofs_get_ino(block_saved,
+							offset_saved, bufbits);
+		}
+
+		if (de->flags[-sbi->s_high_sierra] & 0x80) {
+			first_de = 0;
+			ctx->pos += de_len;
+			continue;
+		}
+		first_de = 1;
+
+		/* Handle the case of the '.' directory */
+		if (de->name_len[0] == 1 && de->name[0] == 0) {
+			if (!dir_emit_dot(file, ctx))
+				break;
+			ctx->pos += de_len;
+			continue;
+		}
+
+		len = 0;
+
+		/* Handle the case of the '..' directory */
+		if (de->name_len[0] == 1 && de->name[0] == 1) {
+			if (!dir_emit_dotdot(file, ctx))
+				break;
+			ctx->pos += de_len;
+			continue;
+		}
+
+		/* Handle everything else.  Do name translation if there
+		   is no Rock Ridge NM field. */
+
+		/*
+		 * Do not report hidden files if so instructed, or associated
+		 * files unless instructed to do so
+		 */
+		if ((sbi->s_hide && (de->flags[-sbi->s_high_sierra] & 1)) ||
+		    (!sbi->s_showassoc &&
+				(de->flags[-sbi->s_high_sierra] & 4))) {
+			ctx->pos += de_len;
+			continue;
+		}
+
+		map = 1;
+		if (sbi->s_rock) {
+			len = get_rock_ridge_filename(de, tmpname, inode);
+			if (len != 0) {		/* may be -1 */
+				p = tmpname;
+				map = 0;
+			}
+		}
+		if (map) {
+#ifdef CONFIG_JOLIET
+			if (sbi->s_joliet_level) {
+				len = get_joliet_filename(de, tmpname, inode);
+				p = tmpname;
+			} else
+#endif
+			if (sbi->s_mapping == 'a') {
+				len = get_acorn_filename(de, tmpname, inode);
+				p = tmpname;
+			} else
+			if (sbi->s_mapping == 'n') {
+				len = isofs_name_translate(de, tmpname, inode);
+				p = tmpname;
+			} else {
+				p = de->name;
+				len = de->name_len[0];
+			}
+		}
+		if (len > 0) {
+			if (!dir_emit(ctx, p, len, inode_number, DT_UNKNOWN))
+				break;
+		}
+		ctx->pos += de_len;
+	}
+	if (bh)
+		brelse(bh);
+	return 0;
+}
+
+/*
+ * Handle allocation of temporary space for name translation and
+ * handling split directory entries.. The real work is done by
+ * "do_isofs_readdir()".
+ */
+static int isofs_readdir(struct file *file, struct dir_context *ctx)
+{
+	int result;
+	char *tmpname;
+	struct inode *inode = file_inode(file);
+
+	tmpname = kmalloc(1024, GFP_KERNEL);
+	if (tmpname == NULL)
+		return -ENOMEM;
+
+	result = do_isofs_readdir(inode, file, ctx, tmpname);
+
+	kfree(tmpname);
+	return result;
+}
+
+int isofs_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
+{
+	struct isofs_sb_info *sbi = ISOFS_SB(dentry->d_sb);
+
+	if (sbi->s_check == 'r') {
+		fa->fsx_xflags |= FS_XFLAG_CASEFOLD;
+		fa->flags |= FS_CASEFOLD_FL;
+	}
+	if (!sbi->s_joliet_level && !sbi->s_rock &&
+	    (sbi->s_mapping == 'n' || sbi->s_mapping == 'a'))
+		fa->fsx_xflags |= FS_XFLAG_CASENONPRESERVING;
+	return 0;
+}
+
+const struct file_operations isofs_dir_operations =
+{
+	.llseek = generic_file_llseek,
+	.read = generic_read_dir,
+	.iterate_shared = isofs_readdir,
+	.setlease = generic_setlease,
+};
+
+/*
+ * directories can handle most operations...
+ */
+const struct inode_operations isofs_dir_inode_operations =
+{
+	.lookup = isofs_lookup,
+	.fileattr_get = isofs_fileattr_get,
+};
+