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, 72 insertions, 0 deletions

diff --git a/drivers/hwspinlock/hwspinlock_internal.h b/drivers/hwspinlock/hwspinlock_internal.h
new file mode 100644
index 000000000..f298fc0ee
--- /dev/null
+++ b/drivers/hwspinlock/hwspinlock_internal.h
@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Hardware spinlocks internal header
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
+ *
+ * Contact: Ohad Ben-Cohen <ohad@wizery.com>
+ */
+
+#ifndef __HWSPINLOCK_HWSPINLOCK_H
+#define __HWSPINLOCK_HWSPINLOCK_H
+
+#include <linux/spinlock.h>
+#include <linux/device.h>
+
+struct hwspinlock_device;
+
+/**
+ * struct hwspinlock_ops - platform-specific hwspinlock handlers
+ *
+ * @trylock: make a single attempt to take the lock. returns 0 on
+ *	     failure and true on success. may _not_ sleep.
+ * @unlock:  release the lock. always succeed. may _not_ sleep.
+ * @bust:    optional, platform-specific bust handler, called by hwspinlock
+ *	     core to bust a specific lock.
+ * @relax:   optional, platform-specific relax handler, called by hwspinlock
+ *	     core while spinning on a lock, between two successive
+ *	     invocations of @trylock. may _not_ sleep.
+ */
+struct hwspinlock_ops {
+	int (*trylock)(struct hwspinlock *lock);
+	void (*unlock)(struct hwspinlock *lock);
+	int (*bust)(struct hwspinlock *lock, unsigned int id);
+	void (*relax)(struct hwspinlock *lock);
+};
+
+/**
+ * struct hwspinlock - this struct represents a single hwspinlock instance
+ * @bank: the hwspinlock_device structure which owns this lock
+ * @lock: initialized and used by hwspinlock core
+ * @priv: private data, owned by the underlying platform-specific hwspinlock drv
+ */
+struct hwspinlock {
+	struct hwspinlock_device *bank;
+	spinlock_t lock;
+	void *priv;
+};
+
+/**
+ * struct hwspinlock_device - a device which usually spans numerous hwspinlocks
+ * @dev: underlying device, will be used to invoke runtime PM api
+ * @ops: platform-specific hwspinlock handlers
+ * @base_id: id index of the first lock in this device
+ * @num_locks: number of locks in this device
+ * @lock: dynamically allocated array of 'struct hwspinlock'
+ */
+struct hwspinlock_device {
+	struct device *dev;
+	const struct hwspinlock_ops *ops;
+	int base_id;
+	int num_locks;
+	struct hwspinlock lock[];
+};
+
+static inline int hwlock_to_id(struct hwspinlock *hwlock)
+{
+	int local_id = hwlock - &hwlock->bank->lock[0];
+
+	return hwlock->bank->base_id + local_id;
+}
+
+#endif /* __HWSPINLOCK_HWSPINLOCK_H */