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, 99 insertions, 0 deletions

diff --git a/drivers/pci/hotplug/rpaphp.h b/drivers/pci/hotplug/rpaphp.h
new file mode 100644
index 000000000..bdc954d70
--- /dev/null
+++ b/drivers/pci/hotplug/rpaphp.h
@@ -0,0 +1,99 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * PCI Hot Plug Controller Driver for RPA-compliant PPC64 platform.
+ *
+ * Copyright (C) 2003 Linda Xie <lxie@us.ibm.com>
+ *
+ * All rights reserved.
+ *
+ * Send feedback to <lxie@us.ibm.com>,
+ *
+ */
+
+#ifndef _PPC64PHP_H
+#define _PPC64PHP_H
+
+#include <linux/pci.h>
+#include <linux/pci_hotplug.h>
+
+#define DR_INDICATOR 9002
+#define DR_ENTITY_SENSE 9003
+
+#define POWER_ON	100
+#define POWER_OFF	0
+
+#define LED_OFF		0
+#define LED_ON		1	/* continuous on */
+#define LED_ID		2	/* slow blinking */
+#define LED_ACTION	3	/* fast blinking */
+
+/* Sensor values from rtas_get-sensor */
+#define EMPTY           0	/* No card in slot */
+#define PRESENT         1	/* Card in slot */
+
+#define MY_NAME "rpaphp"
+extern bool rpaphp_debug;
+#define dbg(format, arg...)					\
+	do {							\
+		if (rpaphp_debug)				\
+			printk(KERN_DEBUG "%s: " format,	\
+				MY_NAME, ## arg);		\
+	} while (0)
+#define err(format, arg...) printk(KERN_ERR "%s: " format, MY_NAME, ## arg)
+#define info(format, arg...) printk(KERN_INFO "%s: " format, MY_NAME, ## arg)
+#define warn(format, arg...) printk(KERN_WARNING "%s: " format, MY_NAME, ## arg)
+
+/* slot states */
+
+#define	NOT_VALID	3
+#define	NOT_CONFIGURED	2
+#define	CONFIGURED	1
+#define	EMPTY		0
+
+/* DRC constants */
+
+#define MAX_DRC_NAME_LEN 64
+
+/*
+ * struct slot - slot information for each *physical* slot
+ */
+struct slot {
+	struct list_head rpaphp_slot_list;
+	int state;
+	u32 index;
+	u32 type;
+	u32 power_domain;
+	u8 attention_status;
+	char *name;
+	struct device_node *dn;
+	struct pci_bus *bus;
+	struct list_head *pci_devs;
+	struct hotplug_slot hotplug_slot;
+};
+
+extern const struct hotplug_slot_ops rpaphp_hotplug_slot_ops;
+extern struct list_head rpaphp_slot_head;
+
+static inline struct slot *to_slot(struct hotplug_slot *hotplug_slot)
+{
+	return container_of(hotplug_slot, struct slot, hotplug_slot);
+}
+
+/* function prototypes */
+
+/* rpaphp_pci.c */
+int rpaphp_enable_slot(struct slot *slot);
+int rpaphp_get_sensor_state(struct slot *slot, int *state);
+
+/* rpaphp_core.c */
+int rpaphp_add_slot(struct device_node *dn);
+int rpaphp_check_drc_props(struct device_node *dn, char *drc_name,
+		char *drc_type);
+
+/* rpaphp_slot.c */
+void dealloc_slot_struct(struct slot *slot);
+struct slot *alloc_slot_struct(struct device_node *dn, int drc_index, char *drc_name, int power_domain);
+int rpaphp_register_slot(struct slot *slot);
+int rpaphp_deregister_slot(struct slot *slot);
+
+#endif				/* _PPC64PHP_H */