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, 187 insertions, 0 deletions

diff --git a/drivers/pci/hotplug/acpiphp.h b/drivers/pci/hotplug/acpiphp.h
new file mode 100644
index 000000000..5745be601
--- /dev/null
+++ b/drivers/pci/hotplug/acpiphp.h
@@ -0,0 +1,187 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * ACPI PCI Hot Plug Controller Driver
+ *
+ * Copyright (C) 1995,2001 Compaq Computer Corporation
+ * Copyright (C) 2001 Greg Kroah-Hartman (greg@kroah.com)
+ * Copyright (C) 2001 IBM Corp.
+ * Copyright (C) 2002 Hiroshi Aono (h-aono@ap.jp.nec.com)
+ * Copyright (C) 2002,2003 Takayoshi Kochi (t-kochi@bq.jp.nec.com)
+ * Copyright (C) 2002,2003 NEC Corporation
+ * Copyright (C) 2003-2005 Matthew Wilcox (willy@infradead.org)
+ * Copyright (C) 2003-2005 Hewlett Packard
+ *
+ * All rights reserved.
+ *
+ * Send feedback to <gregkh@us.ibm.com>,
+ *		    <t-kochi@bq.jp.nec.com>
+ *
+ */
+
+#ifndef _ACPIPHP_H
+#define _ACPIPHP_H
+
+#include <linux/acpi.h>
+#include <linux/mutex.h>
+#include <linux/pci_hotplug.h>
+
+struct acpiphp_context;
+struct acpiphp_bridge;
+struct acpiphp_slot;
+
+/*
+ * struct slot - slot information for each *physical* slot
+ */
+struct slot {
+	struct hotplug_slot	hotplug_slot;
+	struct acpiphp_slot	*acpi_slot;
+	unsigned int sun;	/* ACPI _SUN (Slot User Number) value */
+};
+
+static inline const char *slot_name(struct slot *slot)
+{
+	return hotplug_slot_name(&slot->hotplug_slot);
+}
+
+static inline struct slot *to_slot(struct hotplug_slot *hotplug_slot)
+{
+	return container_of(hotplug_slot, struct slot, hotplug_slot);
+}
+
+/*
+ * struct acpiphp_bridge - PCI bridge information
+ *
+ * for each bridge device in ACPI namespace
+ */
+struct acpiphp_bridge {
+	struct list_head list;
+	struct list_head slots;
+	struct kref ref;
+
+	struct acpiphp_context *context;
+
+	int nr_slots;
+
+	/* This bus (host bridge) or Secondary bus (PCI-to-PCI bridge) */
+	struct pci_bus *pci_bus;
+
+	/* PCI-to-PCI bridge device */
+	struct pci_dev *pci_dev;
+
+	bool is_going_away;
+};
+
+
+/*
+ * struct acpiphp_slot - PCI slot information
+ *
+ * PCI slot information for each *physical* PCI slot
+ */
+struct acpiphp_slot {
+	struct list_head node;
+	struct pci_bus *bus;
+	struct list_head funcs;		/* one slot may have different
+					   objects (i.e. for each function) */
+	struct slot *slot;
+
+	u8		device;		/* pci device# */
+	u32		flags;		/* see below */
+};
+
+
+/*
+ * struct acpiphp_func - PCI function information
+ *
+ * PCI function information for each object in ACPI namespace
+ * typically 8 objects per slot (i.e. for each PCI function)
+ */
+struct acpiphp_func {
+	struct acpiphp_bridge *parent;
+	struct acpiphp_slot *slot;
+
+	struct list_head sibling;
+
+	u8		function;	/* pci function# */
+	u32		flags;		/* see below */
+};
+
+struct acpiphp_context {
+	struct acpi_hotplug_context hp;
+	struct acpiphp_func func;
+	struct acpiphp_bridge *bridge;
+	unsigned int refcount;
+};
+
+static inline struct acpiphp_context *to_acpiphp_context(struct acpi_hotplug_context *hp)
+{
+	return container_of(hp, struct acpiphp_context, hp);
+}
+
+static inline struct acpiphp_context *func_to_context(struct acpiphp_func *func)
+{
+	return container_of(func, struct acpiphp_context, func);
+}
+
+static inline struct acpi_device *func_to_acpi_device(struct acpiphp_func *func)
+{
+	return func_to_context(func)->hp.self;
+}
+
+static inline acpi_handle func_to_handle(struct acpiphp_func *func)
+{
+	return func_to_acpi_device(func)->handle;
+}
+
+struct acpiphp_root_context {
+	struct acpi_hotplug_context hp;
+	struct acpiphp_bridge *root_bridge;
+};
+
+static inline struct acpiphp_root_context *to_acpiphp_root_context(struct acpi_hotplug_context *hp)
+{
+	return container_of(hp, struct acpiphp_root_context, hp);
+}
+
+/*
+ * struct acpiphp_attention_info - device specific attention registration
+ *
+ * ACPI has no generic method of setting/getting attention status
+ * this allows for device specific driver registration
+ */
+struct acpiphp_attention_info {
+	int (*set_attn)(struct hotplug_slot *slot, u8 status);
+	int (*get_attn)(struct hotplug_slot *slot, u8 *status);
+	struct module *owner;
+};
+
+/* ACPI _STA method value (ignore bit 4; battery present) */
+#define ACPI_STA_ALL			(0x0000000f)
+
+/* slot flags */
+
+#define SLOT_ENABLED		(0x00000001)
+#define SLOT_IS_GOING_AWAY	(0x00000002)
+
+/* function flags */
+
+#define FUNC_HAS_STA		(0x00000001)
+#define FUNC_HAS_EJ0		(0x00000002)
+
+/* function prototypes */
+
+/* acpiphp_core.c */
+int acpiphp_register_attention(struct acpiphp_attention_info *info);
+int acpiphp_unregister_attention(struct acpiphp_attention_info *info);
+int acpiphp_register_hotplug_slot(struct acpiphp_slot *slot, unsigned int sun);
+void acpiphp_unregister_hotplug_slot(struct acpiphp_slot *slot);
+
+int acpiphp_enable_slot(struct acpiphp_slot *slot);
+int acpiphp_disable_slot(struct acpiphp_slot *slot);
+u8 acpiphp_get_power_status(struct acpiphp_slot *slot);
+u8 acpiphp_get_latch_status(struct acpiphp_slot *slot);
+u8 acpiphp_get_adapter_status(struct acpiphp_slot *slot);
+
+/* variables */
+extern bool acpiphp_disabled;
+
+#endif /* _ACPIPHP_H */