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, 136 insertions, 0 deletions

diff --git a/fs/jfs/jfs_unicode.h b/fs/jfs/jfs_unicode.h
new file mode 100644
index 000000000..b6a78d4ae
--- /dev/null
+++ b/fs/jfs/jfs_unicode.h
@@ -0,0 +1,136 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ *   Copyright (C) International Business Machines Corp., 2000-2002
+ *   Portions Copyright (C) Christoph Hellwig, 2001-2002
+ */
+#ifndef _H_JFS_UNICODE
+#define _H_JFS_UNICODE
+
+#include <linux/slab.h>
+#include <asm/byteorder.h>
+#include "../nls/nls_ucs2_data.h"
+#include "jfs_types.h"
+
+extern int get_UCSname(struct component_name *, struct dentry *);
+extern int jfs_strfromUCS_le(char *, const __le16 *, int, struct nls_table *);
+
+#define free_UCSname(COMP) kfree((COMP)->name)
+
+/*
+ * UniStrcpy:  Copy a string
+ */
+static inline wchar_t *UniStrcpy(wchar_t * ucs1, const wchar_t * ucs2)
+{
+	wchar_t *anchor = ucs1;	/* save the start of result string */
+
+	while ((*ucs1++ = *ucs2++));
+	return anchor;
+}
+
+
+
+/*
+ * UniStrncpy:  Copy length limited string with pad
+ */
+static inline __le16 *UniStrncpy_le(__le16 * ucs1, const __le16 * ucs2,
+				  size_t n)
+{
+	__le16 *anchor = ucs1;
+
+	while (n-- && *ucs2)	/* Copy the strings */
+		*ucs1++ = *ucs2++;
+
+	n++;
+	while (n--)		/* Pad with nulls */
+		*ucs1++ = 0;
+	return anchor;
+}
+
+/*
+ * UniStrncmp_le:  Compare length limited string - native to little-endian
+ */
+static inline int UniStrncmp_le(const wchar_t * ucs1, const __le16 * ucs2,
+				size_t n)
+{
+	if (!n)
+		return 0;	/* Null strings are equal */
+	while ((*ucs1 == __le16_to_cpu(*ucs2)) && *ucs1 && --n) {
+		ucs1++;
+		ucs2++;
+	}
+	return (int) *ucs1 - (int) __le16_to_cpu(*ucs2);
+}
+
+/*
+ * UniStrncpy_to_le:  Copy length limited string with pad to little-endian
+ */
+static inline __le16 *UniStrncpy_to_le(__le16 * ucs1, const wchar_t * ucs2,
+				       size_t n)
+{
+	__le16 *anchor = ucs1;
+
+	while (n-- && *ucs2)	/* Copy the strings */
+		*ucs1++ = cpu_to_le16(*ucs2++);
+
+	n++;
+	while (n--)		/* Pad with nulls */
+		*ucs1++ = 0;
+	return anchor;
+}
+
+/*
+ * UniStrncpy_from_le:  Copy length limited string with pad from little-endian
+ */
+static inline wchar_t *UniStrncpy_from_le(wchar_t * ucs1, const __le16 * ucs2,
+					  size_t n)
+{
+	wchar_t *anchor = ucs1;
+
+	while (n-- && *ucs2)	/* Copy the strings */
+		*ucs1++ = __le16_to_cpu(*ucs2++);
+
+	n++;
+	while (n--)		/* Pad with nulls */
+		*ucs1++ = 0;
+	return anchor;
+}
+
+/*
+ * UniToupper:  Convert a unicode character to upper case
+ */
+static inline wchar_t UniToupper(wchar_t uc)
+{
+	const struct UniCaseRange *rp;
+
+	if (uc < sizeof(NlsUniUpperTable)) {	/* Latin characters */
+		return uc + NlsUniUpperTable[uc];	/* Use base tables */
+	} else {
+		rp = NlsUniUpperRange;	/* Use range tables */
+		while (rp->start) {
+			if (uc < rp->start)	/* Before start of range */
+				return uc;	/* Uppercase = input */
+			if (uc <= rp->end)	/* In range */
+				return uc + rp->table[uc - rp->start];
+			rp++;	/* Try next range */
+		}
+	}
+	return uc;		/* Past last range */
+}
+
+
+/*
+ * UniStrupr:  Upper case a unicode string
+ */
+static inline wchar_t *UniStrupr(wchar_t * upin)
+{
+	wchar_t *up;
+
+	up = upin;
+	while (*up) {		/* For all characters */
+		*up = UniToupper(*up);
+		up++;
+	}
+	return upin;		/* Return input pointer */
+}
+
+#endif				/* !_H_JFS_UNICODE */