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, 213 insertions, 0 deletions

diff --git a/drivers/usb/gadget/config.c b/drivers/usb/gadget/config.c
new file mode 100644
index 000000000..256364d4b
--- /dev/null
+++ b/drivers/usb/gadget/config.c
@@ -0,0 +1,213 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * usb/gadget/config.c -- simplify building config descriptors
+ *
+ * Copyright (C) 2003 David Brownell
+ */
+
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/string.h>
+#include <linux/device.h>
+
+#include <linux/usb/ch9.h>
+#include <linux/usb/gadget.h>
+#include <linux/usb/composite.h>
+#include <linux/usb/otg.h>
+
+/**
+ * usb_descriptor_fillbuf - fill buffer with descriptors
+ * @buf: Buffer to be filled
+ * @buflen: Size of buf
+ * @src: Array of descriptor pointers, terminated by null pointer.
+ *
+ * Copies descriptors into the buffer, returning the length or a
+ * negative error code if they can't all be copied.  Useful when
+ * assembling descriptors for an associated set of interfaces used
+ * as part of configuring a composite device; or in other cases where
+ * sets of descriptors need to be marshaled.
+ */
+int
+usb_descriptor_fillbuf(void *buf, unsigned buflen,
+		const struct usb_descriptor_header **src)
+{
+	u8	*dest = buf;
+
+	if (!src)
+		return -EINVAL;
+
+	/* fill buffer from src[] until null descriptor ptr */
+	for (; NULL != *src; src++) {
+		unsigned		len = (*src)->bLength;
+
+		if (len > buflen)
+			return -EINVAL;
+		memcpy(dest, *src, len);
+		buflen -= len;
+		dest += len;
+	}
+	return dest - (u8 *)buf;
+}
+EXPORT_SYMBOL_GPL(usb_descriptor_fillbuf);
+
+/**
+ * usb_copy_descriptors - copy a vector of USB descriptors
+ * @src: null-terminated vector to copy
+ * Context: initialization code, which may sleep
+ *
+ * This makes a copy of a vector of USB descriptors.  Its primary use
+ * is to support usb_function objects which can have multiple copies,
+ * each needing different descriptors.  Functions may have static
+ * tables of descriptors, which are used as templates and customized
+ * with identifiers (for interfaces, strings, endpoints, and more)
+ * as needed by a given function instance.
+ */
+struct usb_descriptor_header **
+usb_copy_descriptors(struct usb_descriptor_header **src)
+{
+	struct usb_descriptor_header **tmp;
+	unsigned bytes;
+	unsigned n_desc;
+	void *mem;
+	struct usb_descriptor_header **ret;
+
+	/* count descriptors and their sizes; then add vector size */
+	for (bytes = 0, n_desc = 0, tmp = src; *tmp; tmp++, n_desc++)
+		bytes += (*tmp)->bLength;
+	bytes += (n_desc + 1) * sizeof(*tmp);
+
+	mem = kmalloc(bytes, GFP_KERNEL);
+	if (!mem)
+		return NULL;
+
+	/* fill in pointers starting at "tmp",
+	 * to descriptors copied starting at "mem";
+	 * and return "ret"
+	 */
+	tmp = mem;
+	ret = mem;
+	mem += (n_desc + 1) * sizeof(*tmp);
+	while (*src) {
+		memcpy(mem, *src, (*src)->bLength);
+		*tmp = mem;
+		tmp++;
+		mem += (*src)->bLength;
+		src++;
+	}
+	*tmp = NULL;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(usb_copy_descriptors);
+
+int usb_assign_descriptors(struct usb_function *f,
+		struct usb_descriptor_header **fs,
+		struct usb_descriptor_header **hs,
+		struct usb_descriptor_header **ss,
+		struct usb_descriptor_header **ssp)
+{
+	/* super-speed-plus descriptor falls back to super-speed one,
+	 * if such a descriptor was provided, thus avoiding a NULL
+	 * pointer dereference if a 5gbps capable gadget is used with
+	 * a 10gbps capable config (device port + cable + host port)
+	 */
+	if (!ssp)
+		ssp = ss;
+
+	if (fs) {
+		f->fs_descriptors = usb_copy_descriptors(fs);
+		if (!f->fs_descriptors)
+			goto err;
+	}
+	if (hs) {
+		f->hs_descriptors = usb_copy_descriptors(hs);
+		if (!f->hs_descriptors)
+			goto err;
+	}
+	if (ss) {
+		f->ss_descriptors = usb_copy_descriptors(ss);
+		if (!f->ss_descriptors)
+			goto err;
+	}
+	if (ssp) {
+		f->ssp_descriptors = usb_copy_descriptors(ssp);
+		if (!f->ssp_descriptors)
+			goto err;
+	}
+	return 0;
+err:
+	usb_free_all_descriptors(f);
+	return -ENOMEM;
+}
+EXPORT_SYMBOL_GPL(usb_assign_descriptors);
+
+void usb_free_all_descriptors(struct usb_function *f)
+{
+	usb_free_descriptors(f->fs_descriptors);
+	f->fs_descriptors = NULL;
+	usb_free_descriptors(f->hs_descriptors);
+	f->hs_descriptors = NULL;
+	usb_free_descriptors(f->ss_descriptors);
+	f->ss_descriptors = NULL;
+	usb_free_descriptors(f->ssp_descriptors);
+	f->ssp_descriptors = NULL;
+}
+EXPORT_SYMBOL_GPL(usb_free_all_descriptors);
+
+struct usb_descriptor_header *usb_otg_descriptor_alloc(
+				struct usb_gadget *gadget)
+{
+	struct usb_descriptor_header *otg_desc;
+	unsigned length = 0;
+
+	if (gadget->otg_caps && (gadget->otg_caps->otg_rev >= 0x0200))
+		length = sizeof(struct usb_otg20_descriptor);
+	else
+		length = sizeof(struct usb_otg_descriptor);
+
+	otg_desc = kzalloc(length, GFP_KERNEL);
+	return otg_desc;
+}
+EXPORT_SYMBOL_GPL(usb_otg_descriptor_alloc);
+
+int usb_otg_descriptor_init(struct usb_gadget *gadget,
+		struct usb_descriptor_header *otg_desc)
+{
+	struct usb_otg_descriptor *otg1x_desc;
+	struct usb_otg20_descriptor *otg20_desc;
+	struct usb_otg_caps *otg_caps = gadget->otg_caps;
+	u8 otg_attributes = 0;
+
+	if (!otg_desc)
+		return -EINVAL;
+
+	if (otg_caps && otg_caps->otg_rev) {
+		if (otg_caps->hnp_support)
+			otg_attributes |= USB_OTG_HNP;
+		if (otg_caps->srp_support)
+			otg_attributes |= USB_OTG_SRP;
+		if (otg_caps->adp_support && (otg_caps->otg_rev >= 0x0200))
+			otg_attributes |= USB_OTG_ADP;
+	} else {
+		otg_attributes = USB_OTG_SRP | USB_OTG_HNP;
+	}
+
+	if (otg_caps && (otg_caps->otg_rev >= 0x0200)) {
+		otg20_desc = (struct usb_otg20_descriptor *)otg_desc;
+		otg20_desc->bLength = sizeof(struct usb_otg20_descriptor);
+		otg20_desc->bDescriptorType = USB_DT_OTG;
+		otg20_desc->bmAttributes = otg_attributes;
+		otg20_desc->bcdOTG = cpu_to_le16(otg_caps->otg_rev);
+	} else {
+		otg1x_desc = (struct usb_otg_descriptor *)otg_desc;
+		otg1x_desc->bLength = sizeof(struct usb_otg_descriptor);
+		otg1x_desc->bDescriptorType = USB_DT_OTG;
+		otg1x_desc->bmAttributes = otg_attributes;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usb_otg_descriptor_init);