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, 150 insertions, 0 deletions

diff --git a/fs/hfs/trans.c b/fs/hfs/trans.c
new file mode 100644
index 000000000..fdb0edb8a
--- /dev/null
+++ b/fs/hfs/trans.c
@@ -0,0 +1,150 @@
+/*
+ *  linux/fs/hfs/trans.c
+ *
+ * Copyright (C) 1995-1997  Paul H. Hargrove
+ * This file may be distributed under the terms of the GNU General Public License.
+ *
+ * This file contains routines for converting between the Macintosh
+ * character set and various other encodings.  This includes dealing
+ * with ':' vs. '/' as the path-element separator.
+ */
+
+#include <linux/types.h>
+#include <linux/nls.h>
+
+#include "hfs_fs.h"
+
+/*================ Global functions ================*/
+
+/*
+ * hfs_mac2asc()
+ *
+ * Given a 'Pascal String' (a string preceded by a length byte) in
+ * the Macintosh character set produce the corresponding filename using
+ * the 'trivial' name-mangling scheme, returning the length of the
+ * mangled filename.  Note that the output string is not NULL
+ * terminated.
+ *
+ * The name-mangling works as follows:
+ * The character '/', which is illegal in Linux filenames is replaced
+ * by ':' which never appears in HFS filenames.	 All other characters
+ * are passed unchanged from input to output.
+ */
+int hfs_mac2asc(struct super_block *sb, char *out, const struct hfs_name *in)
+{
+	struct nls_table *nls_disk = HFS_SB(sb)->nls_disk;
+	struct nls_table *nls_io = HFS_SB(sb)->nls_io;
+	const char *src;
+	char *dst;
+	int srclen, dstlen, size;
+
+	src = in->name;
+	srclen = in->len;
+	if (srclen > HFS_NAMELEN)
+		srclen = HFS_NAMELEN;
+	dst = out;
+	dstlen = HFS_MAX_NAMELEN;
+	if (nls_io) {
+		wchar_t ch;
+
+		while (srclen > 0) {
+			if (nls_disk) {
+				size = nls_disk->char2uni(src, srclen, &ch);
+				if (size <= 0) {
+					ch = '?';
+					size = 1;
+				}
+				src += size;
+				srclen -= size;
+			} else {
+				ch = *src++;
+				srclen--;
+			}
+			if (ch == '/')
+				ch = ':';
+			size = nls_io->uni2char(ch, dst, dstlen);
+			if (size < 0) {
+				if (size == -ENAMETOOLONG)
+					goto out;
+				*dst = '?';
+				size = 1;
+			}
+			dst += size;
+			dstlen -= size;
+		}
+	} else {
+		char ch;
+
+		while (--srclen >= 0)
+			*dst++ = (ch = *src++) == '/' ? ':' : ch;
+	}
+out:
+	return dst - out;
+}
+
+/*
+ * hfs_asc2mac()
+ *
+ * Given an ASCII string (not null-terminated) and its length,
+ * generate the corresponding filename in the Macintosh character set
+ * using the 'trivial' name-mangling scheme, returning the length of
+ * the mangled filename.  Note that the output string is not NULL
+ * terminated.
+ *
+ * This routine is a inverse to hfs_mac2triv().
+ * A ':' is replaced by a '/'.
+ */
+void hfs_asc2mac(struct super_block *sb, struct hfs_name *out, const struct qstr *in)
+{
+	struct nls_table *nls_disk = HFS_SB(sb)->nls_disk;
+	struct nls_table *nls_io = HFS_SB(sb)->nls_io;
+	const char *src;
+	char *dst;
+	int srclen, dstlen, size;
+
+	src = in->name;
+	srclen = in->len;
+	dst = out->name;
+	dstlen = HFS_NAMELEN;
+	if (nls_io) {
+		wchar_t ch;
+
+		while (srclen > 0 && dstlen > 0) {
+			size = nls_io->char2uni(src, srclen, &ch);
+			if (size < 0) {
+				ch = '?';
+				size = 1;
+			}
+			src += size;
+			srclen -= size;
+			if (ch == ':')
+				ch = '/';
+			if (nls_disk) {
+				size = nls_disk->uni2char(ch, dst, dstlen);
+				if (size < 0) {
+					if (size == -ENAMETOOLONG)
+						goto out;
+					*dst = '?';
+					size = 1;
+				}
+				dst += size;
+				dstlen -= size;
+			} else {
+				*dst++ = ch > 0xff ? '?' : ch;
+				dstlen--;
+			}
+		}
+	} else {
+		char ch;
+
+		if (dstlen > srclen)
+			dstlen = srclen;
+		while (--dstlen >= 0)
+			*dst++ = (ch = *src++) == ':' ? '/' : ch;
+	}
+out:
+	out->len = dst - (char *)out->name;
+	dstlen = HFS_NAMELEN - out->len;
+	while (--dstlen >= 0)
+		*dst++ = 0;
+}