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, 114 insertions, 0 deletions

diff --git a/fs/hpfs/name.c b/fs/hpfs/name.c
new file mode 100644
index 000000000..ef7ba77f3
--- /dev/null
+++ b/fs/hpfs/name.c
@@ -0,0 +1,114 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  linux/fs/hpfs/name.c
+ *
+ *  Mikulas Patocka (mikulas@artax.karlin.mff.cuni.cz), 1998-1999
+ *
+ *  operations with filenames
+ */
+
+#include "hpfs_fn.h"
+
+static inline int not_allowed_char(unsigned char c)
+{
+	return c<' ' || c=='"' || c=='*' || c=='/' || c==':' || c=='<' ||
+	      c=='>' || c=='?' || c=='\\' || c=='|';
+}
+
+static inline int no_dos_char(unsigned char c)
+{	/* Characters that are allowed in HPFS but not in DOS */
+	return c=='+' || c==',' || c==';' || c=='=' || c=='[' || c==']';
+}
+
+static inline unsigned char upcase(unsigned char *dir, unsigned char a)
+{
+	if (a<128 || a==255) return a>='a' && a<='z' ? a - 0x20 : a;
+	if (!dir) return a;
+	return dir[a-128];
+}
+
+unsigned char hpfs_upcase(unsigned char *dir, unsigned char a)
+{
+	return upcase(dir, a);
+}
+
+static inline unsigned char locase(unsigned char *dir, unsigned char a)
+{
+	if (a<128 || a==255) return a>='A' && a<='Z' ? a + 0x20 : a;
+	if (!dir) return a;
+	return dir[a];
+}
+
+int hpfs_chk_name(const unsigned char *name, unsigned *len)
+{
+	int i;
+	if (*len > 254) return -ENAMETOOLONG;
+	hpfs_adjust_length(name, len);
+	if (!*len) return -EINVAL;
+	for (i = 0; i < *len; i++) if (not_allowed_char(name[i])) return -EINVAL;
+	if (*len == 1) if (name[0] == '.') return -EINVAL;
+	if (*len == 2) if (name[0] == '.' && name[1] == '.') return -EINVAL;
+	return 0;
+}
+
+unsigned char *hpfs_translate_name(struct super_block *s, unsigned char *from,
+			  unsigned len, int lc, int lng)
+{
+	unsigned char *to;
+	int i;
+	if (hpfs_sb(s)->sb_chk >= 2) if (hpfs_is_name_long(from, len) != lng) {
+		pr_err("Long name flag mismatch - name ");
+		for (i = 0; i < len; i++)
+			pr_cont("%c", from[i]);
+		pr_cont(" misidentified as %s.\n", lng ? "short" : "long");
+		pr_err("It's nothing serious. It could happen because of bug in OS/2.\nSet checks=normal to disable this message.\n");
+	}
+	if (!lc) return from;
+	if (!(to = kmalloc(len, GFP_KERNEL))) {
+		pr_err("can't allocate memory for name conversion buffer\n");
+		return from;
+	}
+	for (i = 0; i < len; i++) to[i] = locase(hpfs_sb(s)->sb_cp_table,from[i]);
+	return to;
+}
+
+int hpfs_compare_names(struct super_block *s,
+		       const unsigned char *n1, unsigned l1,
+		       const unsigned char *n2, unsigned l2, int last)
+{
+	unsigned l = l1 < l2 ? l1 : l2;
+	unsigned i;
+	if (last) return -1;
+	for (i = 0; i < l; i++) {
+		unsigned char c1 = upcase(hpfs_sb(s)->sb_cp_table,n1[i]);
+		unsigned char c2 = upcase(hpfs_sb(s)->sb_cp_table,n2[i]);
+		if (c1 < c2) return -1;
+		if (c1 > c2) return 1;
+	}
+	if (l1 < l2) return -1;
+	if (l1 > l2) return 1;
+	return 0;
+}
+
+int hpfs_is_name_long(const unsigned char *name, unsigned len)
+{
+	int i,j;
+	for (i = 0; i < len && name[i] != '.'; i++)
+		if (no_dos_char(name[i])) return 1;
+	if (!i || i > 8) return 1;
+	if (i == len) return 0;
+	for (j = i + 1; j < len; j++)
+		if (name[j] == '.' || no_dos_char(name[i])) return 1;
+	return j - i > 4;
+}
+
+/* OS/2 clears dots and spaces at the end of file name, so we have to */
+
+void hpfs_adjust_length(const unsigned char *name, unsigned *len)
+{
+	if (!*len) return;
+	if (*len == 1 && name[0] == '.') return;
+	if (*len == 2 && name[0] == '.' && name[1] == '.') return;
+	while (*len && (name[*len - 1] == '.' || name[*len - 1] == ' '))
+		(*len)--;
+}