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, 119 insertions, 0 deletions

diff --git a/fs/hfs/string.c b/fs/hfs/string.c
new file mode 100644
index 000000000..0cfa35e82
--- /dev/null
+++ b/fs/hfs/string.c
@@ -0,0 +1,119 @@
+/*
+ *  linux/fs/hfs/string.c
+ *
+ * Copyright (C) 1995-1997  Paul H. Hargrove
+ * (C) 2003 Ardis Technologies <roman@ardistech.com>
+ * This file may be distributed under the terms of the GNU General Public License.
+ *
+ * This file contains the string comparison function for the
+ * Macintosh character set.
+ *
+ * The code in this file is derived from code which is copyright
+ * 1986, 1989, 1990 by Abacus Research and Development, Inc. (ARDI)
+ * It is used here by the permission of ARDI's president Cliff Matthews.
+ */
+
+#include "hfs_fs.h"
+#include <linux/dcache.h>
+
+#include <kunit/visibility.h>
+
+/*================ File-local variables ================*/
+
+/*
+ * unsigned char caseorder[]
+ *
+ * Defines the lexical ordering of characters on the Macintosh
+ *
+ * Composition of the 'casefold' and 'order' tables from ARDI's code
+ * with the entry for 0x20 changed to match that for 0xCA to remove
+ * special case for those two characters.
+ */
+static unsigned char caseorder[256] = {
+	0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0A,0x0B,0x0C,0x0D,0x0E,0x0F,
+	0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17,0x18,0x19,0x1A,0x1B,0x1C,0x1D,0x1E,0x1F,
+	0x20,0x22,0x23,0x28,0x29,0x2A,0x2B,0x2C,0x2F,0x30,0x31,0x32,0x33,0x34,0x35,0x36,
+	0x37,0x38,0x39,0x3A,0x3B,0x3C,0x3D,0x3E,0x3F,0x40,0x41,0x42,0x43,0x44,0x45,0x46,
+	0x47,0x48,0x57,0x59,0x5D,0x5F,0x66,0x68,0x6A,0x6C,0x72,0x74,0x76,0x78,0x7A,0x7E,
+	0x8C,0x8E,0x90,0x92,0x95,0x97,0x9E,0xA0,0xA2,0xA4,0xA7,0xA9,0xAA,0xAB,0xAC,0xAD,
+	0x4E,0x48,0x57,0x59,0x5D,0x5F,0x66,0x68,0x6A,0x6C,0x72,0x74,0x76,0x78,0x7A,0x7E,
+	0x8C,0x8E,0x90,0x92,0x95,0x97,0x9E,0xA0,0xA2,0xA4,0xA7,0xAF,0xB0,0xB1,0xB2,0xB3,
+	0x4A,0x4C,0x5A,0x60,0x7B,0x7F,0x98,0x4F,0x49,0x51,0x4A,0x4B,0x4C,0x5A,0x60,0x63,
+	0x64,0x65,0x6E,0x6F,0x70,0x71,0x7B,0x84,0x85,0x86,0x7F,0x80,0x9A,0x9B,0x9C,0x98,
+	0xB4,0xB5,0xB6,0xB7,0xB8,0xB9,0xBA,0x94,0xBB,0xBC,0xBD,0xBE,0xBF,0xC0,0x4D,0x81,
+	0xC1,0xC2,0xC3,0xC4,0xC5,0xC6,0xC7,0xC8,0xC9,0xCA,0xCB,0x55,0x8A,0xCC,0x4D,0x81,
+	0xCD,0xCE,0xCF,0xD0,0xD1,0xD2,0xD3,0x26,0x27,0xD4,0x20,0x49,0x4B,0x80,0x82,0x82,
+	0xD5,0xD6,0x24,0x25,0x2D,0x2E,0xD7,0xD8,0xA6,0xD9,0xDA,0xDB,0xDC,0xDD,0xDE,0xDF,
+	0xE0,0xE1,0xE2,0xE3,0xE4,0xE5,0xE6,0xE7,0xE8,0xE9,0xEA,0xEB,0xEC,0xED,0xEE,0xEF,
+	0xF0,0xF1,0xF2,0xF3,0xF4,0xF5,0xF6,0xF7,0xF8,0xF9,0xFA,0xFB,0xFC,0xFD,0xFE,0xFF
+};
+
+/*================ Global functions ================*/
+
+/*
+ * Hash a string to an integer in a case-independent way
+ */
+int hfs_hash_dentry(const struct dentry *dentry, struct qstr *this)
+{
+	const unsigned char *name = this->name;
+	unsigned int hash, len = this->len;
+
+	if (len > HFS_NAMELEN)
+		len = HFS_NAMELEN;
+
+	hash = init_name_hash(dentry);
+	for (; len; len--)
+		hash = partial_name_hash(caseorder[*name++], hash);
+	this->hash = end_name_hash(hash);
+	return 0;
+}
+EXPORT_SYMBOL_IF_KUNIT(hfs_hash_dentry);
+
+/*
+ * Compare two strings in the HFS filename character ordering
+ * Returns positive, negative, or zero, not just 0 or (+/-)1
+ *
+ * Equivalent to ARDI's call:
+ *	ROMlib_RelString(s1+1, s2+1, true, false, (s1[0]<<16) | s2[0])
+ */
+int hfs_strcmp(const unsigned char *s1, unsigned int len1,
+	       const unsigned char *s2, unsigned int len2)
+{
+	int len, tmp;
+
+	len = (len1 > len2) ? len2 : len1;
+
+	while (len--) {
+		tmp = (int)caseorder[*(s1++)] - (int)caseorder[*(s2++)];
+		if (tmp)
+			return tmp;
+	}
+	return len1 - len2;
+}
+EXPORT_SYMBOL_IF_KUNIT(hfs_strcmp);
+
+/*
+ * Test for equality of two strings in the HFS filename character ordering.
+ * return 1 on failure and 0 on success
+ */
+int hfs_compare_dentry(const struct dentry *dentry,
+		unsigned int len, const char *str, const struct qstr *name)
+{
+	const unsigned char *n1, *n2;
+
+	if (len >= HFS_NAMELEN) {
+		if (name->len < HFS_NAMELEN)
+			return 1;
+		len = HFS_NAMELEN;
+	} else if (len != name->len)
+		return 1;
+
+	n1 = str;
+	n2 = name->name;
+	while (len--) {
+		if (caseorder[*n1++] != caseorder[*n2++])
+			return 1;
+	}
+	return 0;
+}
+EXPORT_SYMBOL_IF_KUNIT(hfs_compare_dentry);