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, 125 insertions, 0 deletions

diff --git a/fs/jfs/jfs_unicode.c b/fs/jfs/jfs_unicode.c
new file mode 100644
index 000000000..0c1e90272
--- /dev/null
+++ b/fs/jfs/jfs_unicode.c
@@ -0,0 +1,125 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *   Copyright (C) International Business Machines Corp., 2000-2004
+ */
+
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include "jfs_incore.h"
+#include "jfs_filsys.h"
+#include "jfs_unicode.h"
+#include "jfs_debug.h"
+
+/*
+ * NAME:	jfs_strfromUCS()
+ *
+ * FUNCTION:	Convert little-endian unicode string to character string
+ *
+ */
+int jfs_strfromUCS_le(char *to, const __le16 * from,
+		      int len, struct nls_table *codepage)
+{
+	int i;
+	int outlen = 0;
+	static int warn_again = 5;	/* Only warn up to 5 times total */
+	int warn = !!warn_again;	/* once per string */
+
+	if (codepage) {
+		for (i = 0; (i < len) && from[i]; i++) {
+			int charlen;
+			charlen =
+			    codepage->uni2char(le16_to_cpu(from[i]),
+					       &to[outlen],
+					       NLS_MAX_CHARSET_SIZE);
+			if (charlen > 0)
+				outlen += charlen;
+			else
+				to[outlen++] = '?';
+		}
+	} else {
+		for (i = 0; (i < len) && from[i]; i++) {
+			if (unlikely(le16_to_cpu(from[i]) & 0xff00)) {
+				to[i] = '?';
+				if (unlikely(warn)) {
+					warn--;
+					warn_again--;
+					printk(KERN_ERR
+			"non-latin1 character 0x%x found in JFS file name\n",
+					       le16_to_cpu(from[i]));
+					printk(KERN_ERR
+				"mount with iocharset=utf8 to access\n");
+				}
+
+			}
+			else
+				to[i] = (char) (le16_to_cpu(from[i]));
+		}
+		outlen = i;
+	}
+	to[outlen] = 0;
+	return outlen;
+}
+
+/*
+ * NAME:	jfs_strtoUCS()
+ *
+ * FUNCTION:	Convert character string to unicode string
+ *
+ */
+static int jfs_strtoUCS(wchar_t * to, const unsigned char *from, int len,
+		struct nls_table *codepage)
+{
+	int charlen;
+	int i;
+
+	if (codepage) {
+		for (i = 0; len && *from; i++, from += charlen, len -= charlen)
+		{
+			charlen = codepage->char2uni(from, len, &to[i]);
+			if (charlen < 1) {
+				jfs_err("jfs_strtoUCS: char2uni returned %d.",
+					charlen);
+				jfs_err("charset = %s, char = 0x%x",
+					codepage->charset, *from);
+				return charlen;
+			}
+		}
+	} else {
+		for (i = 0; (i < len) && from[i]; i++)
+			to[i] = (wchar_t) from[i];
+	}
+
+	to[i] = 0;
+	return i;
+}
+
+/*
+ * NAME:	get_UCSname()
+ *
+ * FUNCTION:	Allocate and translate to unicode string
+ *
+ */
+int get_UCSname(struct component_name * uniName, struct dentry *dentry)
+{
+	struct nls_table *nls_tab = JFS_SBI(dentry->d_sb)->nls_tab;
+	int length = dentry->d_name.len;
+
+	if (length > JFS_NAME_MAX)
+		return -ENAMETOOLONG;
+
+	uniName->name =
+	    kmalloc_array(length + 1, sizeof(wchar_t), GFP_NOFS);
+
+	if (uniName->name == NULL)
+		return -ENOMEM;
+
+	uniName->namlen = jfs_strtoUCS(uniName->name, dentry->d_name.name,
+				       length, nls_tab);
+
+	if (uniName->namlen < 0) {
+		kfree(uniName->name);
+		return uniName->namlen;
+	}
+
+	return 0;
+}