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, 105 insertions, 0 deletions

diff --git a/drivers/usb/usbip/stub.h b/drivers/usb/usbip/stub.h
new file mode 100644
index 000000000..d11270560
--- /dev/null
+++ b/drivers/usb/usbip/stub.h
@@ -0,0 +1,105 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2003-2008 Takahiro Hirofuchi
+ */
+
+#ifndef __USBIP_STUB_H
+#define __USBIP_STUB_H
+
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+#include <linux/usb.h>
+#include <linux/wait.h>
+
+#define STUB_BUSID_OTHER 0
+#define STUB_BUSID_REMOV 1
+#define STUB_BUSID_ADDED 2
+#define STUB_BUSID_ALLOC 3
+
+struct stub_device {
+	struct usb_device *udev;
+
+	struct usbip_device ud;
+	__u32 devid;
+
+	/*
+	 * stub_priv preserves private data of each urb.
+	 * It is allocated as stub_priv_cache and assigned to urb->context.
+	 *
+	 * stub_priv is always linked to any one of 3 lists;
+	 *	priv_init: linked to this until the comletion of a urb.
+	 *	priv_tx  : linked to this after the completion of a urb.
+	 *	priv_free: linked to this after the sending of the result.
+	 *
+	 * Any of these list operations should be locked by priv_lock.
+	 */
+	spinlock_t priv_lock;
+	struct list_head priv_init;
+	struct list_head priv_tx;
+	struct list_head priv_free;
+
+	/* see comments for unlinking in stub_rx.c */
+	struct list_head unlink_tx;
+	struct list_head unlink_free;
+
+	wait_queue_head_t tx_waitq;
+};
+
+/* private data into urb->priv */
+struct stub_priv {
+	unsigned long seqnum;
+	struct list_head list;
+	struct stub_device *sdev;
+	struct urb **urbs;
+	struct scatterlist *sgl;
+	int num_urbs;
+	int completed_urbs;
+	int urb_status;
+
+	int unlinking;
+};
+
+struct stub_unlink {
+	unsigned long seqnum;
+	struct list_head list;
+	__u32 status;
+};
+
+/* same as SYSFS_BUS_ID_SIZE */
+#define BUSID_SIZE 32
+
+struct bus_id_priv {
+	char name[BUSID_SIZE];
+	char status;
+	int interf_count;
+	struct stub_device *sdev;
+	struct usb_device *udev;
+	char shutdown_busid;
+	spinlock_t busid_lock;
+};
+
+/* stub_priv is allocated from stub_priv_cache */
+extern struct kmem_cache *stub_priv_cache;
+
+/* stub_dev.c */
+extern struct usb_device_driver stub_driver;
+
+/* stub_main.c */
+struct bus_id_priv *get_busid_priv(const char *busid);
+void put_busid_priv(struct bus_id_priv *bid);
+int del_match_busid(char *busid);
+void stub_free_priv_and_urb(struct stub_priv *priv);
+void stub_device_cleanup_urbs(struct stub_device *sdev);
+
+/* stub_rx.c */
+int stub_rx_loop(void *data);
+
+/* stub_tx.c */
+void stub_enqueue_ret_unlink(struct stub_device *sdev, __u32 seqnum,
+			     __u32 status);
+void stub_complete(struct urb *urb);
+int stub_tx_loop(void *data);
+
+#endif /* __USBIP_STUB_H */