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, 102 insertions, 0 deletions

diff --git a/drivers/accessibility/speakup/utils.h b/drivers/accessibility/speakup/utils.h
new file mode 100644
index 000000000..db00c962f
--- /dev/null
+++ b/drivers/accessibility/speakup/utils.h
@@ -0,0 +1,102 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/* utils.h
+ * originally written by: Kirk Reiser.
+ *
+ ** Copyright (C) 2002  Kirk Reiser.
+ *  Copyright (C) 2003  David Borowski.
+ */
+
+#include <stdio.h>
+
+#define MAXKEYS 512
+#define MAXKEYVAL 160
+#define HASHSIZE 101
+#define is_shift -3
+#define is_spk -2
+#define is_input -1
+
+struct st_key {
+	char *name;
+	struct st_key *next;
+	int value, shift;
+};
+
+struct st_key key_table[MAXKEYS];
+struct st_key *extra_keys = key_table+HASHSIZE;
+char *def_name, *def_val;
+FILE *infile;
+int lc;
+
+char filename[256];
+
+static inline void open_input(const char *dir_name, const char *name)
+{
+	if (dir_name)
+		snprintf(filename, sizeof(filename), "%s/%s", dir_name, name);
+	else
+		snprintf(filename, sizeof(filename), "%s", name);
+	infile = fopen(filename, "r");
+	if (!infile) {
+		fprintf(stderr, "can't open %s\n", filename);
+		exit(1);
+	}
+	lc = 0;
+}
+
+static inline int oops(const char *msg, const char *info)
+{
+	if (info == NULL)
+		info = "";
+	fprintf(stderr, "error: file %s line %d\n", filename, lc);
+	fprintf(stderr, "%s %s\n", msg, info);
+	exit(1);
+}
+
+static inline struct st_key *hash_name(char *name)
+{
+	unsigned char *pn = (unsigned char *)name;
+	int hash = 0;
+
+	while (*pn) {
+		hash = (hash * 17) & 0xfffffff;
+		if (isupper(*pn))
+			*pn = tolower(*pn);
+		hash += (int)*pn;
+		pn++;
+	}
+	hash %= HASHSIZE;
+	return &key_table[hash];
+}
+
+static inline struct st_key *find_key(char *name)
+{
+	struct st_key *this = hash_name(name);
+
+	while (this) {
+		if (this->name && !strcmp(name, this->name))
+			return this;
+		this = this->next;
+	}
+	return this;
+}
+
+static inline struct st_key *add_key(char *name, int value, int shift)
+{
+	struct st_key *this = hash_name(name);
+
+	if (extra_keys-key_table >= MAXKEYS)
+		oops("out of key table space, enlarge MAXKEYS", NULL);
+	if (this->name != NULL) {
+		while (this->next) {
+			if (!strcmp(name, this->name))
+				oops("attempt to add duplicate key", name);
+			this = this->next;
+		}
+		this->next = extra_keys++;
+		this = this->next;
+	}
+	this->name = strdup(name);
+	this->value = value;
+	this->shift = shift;
+	return this;
+}