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, 272 insertions, 0 deletions

diff --git a/drivers/usb/misc/emi62.c b/drivers/usb/misc/emi62.c
new file mode 100644
index 000000000..3eea60437
--- /dev/null
+++ b/drivers/usb/misc/emi62.c
@@ -0,0 +1,272 @@
+// SPDX-License-Identifier: GPL-2.0
+/* 
+ * Emagic EMI 2|6 usb audio interface firmware loader.
+ * Copyright (C) 2002
+ * 	Tapio Laxström (tapio.laxstrom@iptime.fi)
+ */
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/usb.h>
+#include <linux/delay.h>
+#include <linux/firmware.h>
+#include <linux/ihex.h>
+
+/* include firmware (variables)*/
+
+/* FIXME: This is quick and dirty solution! */
+#define SPDIF	/* if you want SPDIF comment next line */
+//#undef SPDIF	/* if you want MIDI uncomment this line */ 
+
+#ifdef SPDIF
+#define FIRMWARE_FW "emi62/spdif.fw"
+#else
+#define FIRMWARE_FW "emi62/midi.fw"
+#endif
+
+#define EMI62_VENDOR_ID 		0x086a  /* Emagic Soft-und Hardware GmBH */
+#define EMI62_PRODUCT_ID		0x0110	/* EMI 6|2m without firmware */
+
+#define ANCHOR_LOAD_INTERNAL	0xA0	/* Vendor specific request code for Anchor Upload/Download (This one is implemented in the core) */
+#define ANCHOR_LOAD_EXTERNAL	0xA3	/* This command is not implemented in the core. Requires firmware */
+#define ANCHOR_LOAD_FPGA	0xA5	/* This command is not implemented in the core. Requires firmware. Emagic extension */
+#define MAX_INTERNAL_ADDRESS	0x1B3F	/* This is the highest internal RAM address for the AN2131Q */
+#define CPUCS_REG		0x7F92  /* EZ-USB Control and Status Register.  Bit 0 controls 8051 reset */ 
+#define INTERNAL_RAM(address)   (address <= MAX_INTERNAL_ADDRESS)
+
+static int emi62_writememory(struct usb_device *dev, int address,
+			     const unsigned char *data, int length,
+			     __u8 bRequest);
+static int emi62_set_reset(struct usb_device *dev, unsigned char reset_bit);
+static int emi62_load_firmware (struct usb_device *dev);
+static int emi62_probe(struct usb_interface *intf, const struct usb_device_id *id);
+static void emi62_disconnect(struct usb_interface *intf);
+
+/* thanks to drivers/usb/serial/keyspan_pda.c code */
+static int emi62_writememory(struct usb_device *dev, int address,
+			     const unsigned char *data, int length,
+			     __u8 request)
+{
+	int result;
+	unsigned char *buffer =  kmemdup(data, length, GFP_KERNEL);
+
+	if (!buffer) {
+		dev_err(&dev->dev, "kmalloc(%d) failed.\n", length);
+		return -ENOMEM;
+	}
+	/* Note: usb_control_msg returns negative value on error or length of the
+	 * 		 data that was written! */
+	result = usb_control_msg (dev, usb_sndctrlpipe(dev, 0), request, 0x40, address, 0, buffer, length, 300);
+	kfree (buffer);
+	return result;
+}
+
+/* thanks to drivers/usb/serial/keyspan_pda.c code */
+static int emi62_set_reset (struct usb_device *dev, unsigned char reset_bit)
+{
+	int response;
+	dev_info(&dev->dev, "%s - %d\n", __func__, reset_bit);
+	
+	response = emi62_writememory (dev, CPUCS_REG, &reset_bit, 1, 0xa0);
+	if (response < 0)
+		dev_err(&dev->dev, "set_reset (%d) failed\n", reset_bit);
+	return response;
+}
+
+#define FW_LOAD_SIZE		1023
+
+static int emi62_load_firmware (struct usb_device *dev)
+{
+	const struct firmware *loader_fw = NULL;
+	const struct firmware *bitstream_fw = NULL;
+	const struct firmware *firmware_fw = NULL;
+	const struct ihex_binrec *rec;
+	int err = -ENOMEM;
+	int i;
+	__u32 addr;	/* Address to write */
+	__u8 *buf;
+
+	dev_dbg(&dev->dev, "load_firmware\n");
+	buf = kmalloc(FW_LOAD_SIZE, GFP_KERNEL);
+	if (!buf)
+		goto wraperr;
+
+	err = request_ihex_firmware(&loader_fw, "emi62/loader.fw", &dev->dev);
+	if (err)
+		goto nofw;
+
+	err = request_ihex_firmware(&bitstream_fw, "emi62/bitstream.fw",
+				    &dev->dev);
+	if (err)
+		goto nofw;
+
+	err = request_ihex_firmware(&firmware_fw, FIRMWARE_FW, &dev->dev);
+	if (err) {
+	nofw:
+		goto wraperr;
+	}
+
+	/* Assert reset (stop the CPU in the EMI) */
+	err = emi62_set_reset(dev,1);
+	if (err < 0)
+		goto wraperr;
+
+	rec = (const struct ihex_binrec *)loader_fw->data;
+
+	/* 1. We need to put the loader for the FPGA into the EZ-USB */
+	while (rec) {
+		err = emi62_writememory(dev, be32_to_cpu(rec->addr),
+					rec->data, be16_to_cpu(rec->len),
+					ANCHOR_LOAD_INTERNAL);
+		if (err < 0)
+			goto wraperr;
+		rec = ihex_next_binrec(rec);
+	}
+
+	/* De-assert reset (let the CPU run) */
+	err = emi62_set_reset(dev,0);
+	if (err < 0)
+		goto wraperr;
+	msleep(250);	/* let device settle */
+
+	/* 2. We upload the FPGA firmware into the EMI
+	 * Note: collect up to 1023 (yes!) bytes and send them with
+	 * a single request. This is _much_ faster! */
+	rec = (const struct ihex_binrec *)bitstream_fw->data;
+	do {
+		i = 0;
+		addr = be32_to_cpu(rec->addr);
+
+		/* intel hex records are terminated with type 0 element */
+		while (rec && (i + be16_to_cpu(rec->len) < FW_LOAD_SIZE)) {
+			memcpy(buf + i, rec->data, be16_to_cpu(rec->len));
+			i += be16_to_cpu(rec->len);
+			rec = ihex_next_binrec(rec);
+		}
+		err = emi62_writememory(dev, addr, buf, i, ANCHOR_LOAD_FPGA);
+		if (err < 0)
+			goto wraperr;
+	} while (rec);
+
+	/* Assert reset (stop the CPU in the EMI) */
+	err = emi62_set_reset(dev,1);
+	if (err < 0)
+		goto wraperr;
+
+	/* 3. We need to put the loader for the firmware into the EZ-USB (again...) */
+	for (rec = (const struct ihex_binrec *)loader_fw->data;
+	     rec; rec = ihex_next_binrec(rec)) {
+		err = emi62_writememory(dev, be32_to_cpu(rec->addr),
+					rec->data, be16_to_cpu(rec->len),
+					ANCHOR_LOAD_INTERNAL);
+		if (err < 0)
+			goto wraperr;
+	}
+
+	/* De-assert reset (let the CPU run) */
+	err = emi62_set_reset(dev,0);
+	if (err < 0)
+		goto wraperr;
+	msleep(250);	/* let device settle */
+
+	/* 4. We put the part of the firmware that lies in the external RAM into the EZ-USB */
+
+	for (rec = (const struct ihex_binrec *)firmware_fw->data;
+	     rec; rec = ihex_next_binrec(rec)) {
+		if (!INTERNAL_RAM(be32_to_cpu(rec->addr))) {
+			err = emi62_writememory(dev, be32_to_cpu(rec->addr),
+						rec->data, be16_to_cpu(rec->len),
+						ANCHOR_LOAD_EXTERNAL);
+			if (err < 0)
+				goto wraperr;
+		}
+	}
+
+	/* Assert reset (stop the CPU in the EMI) */
+	err = emi62_set_reset(dev,1);
+	if (err < 0)
+		goto wraperr;
+
+	for (rec = (const struct ihex_binrec *)firmware_fw->data;
+	     rec; rec = ihex_next_binrec(rec)) {
+		if (INTERNAL_RAM(be32_to_cpu(rec->addr))) {
+			err = emi62_writememory(dev, be32_to_cpu(rec->addr),
+						rec->data, be16_to_cpu(rec->len),
+						ANCHOR_LOAD_EXTERNAL);
+			if (err < 0)
+				goto wraperr;
+		}
+	}
+
+	/* De-assert reset (let the CPU run) */
+	err = emi62_set_reset(dev,0);
+	if (err < 0)
+		goto wraperr;
+	msleep(250);	/* let device settle */
+
+	release_firmware(loader_fw);
+	release_firmware(bitstream_fw);
+	release_firmware(firmware_fw);
+
+	kfree(buf);
+
+	/* return 1 to fail the driver inialization
+	 * and give real driver change to load */
+	return 1;
+
+wraperr:
+	if (err < 0)
+		dev_err(&dev->dev,"%s - error loading firmware: error = %d\n",
+			__func__, err);
+	release_firmware(loader_fw);
+	release_firmware(bitstream_fw);
+	release_firmware(firmware_fw);
+
+	kfree(buf);
+	dev_err(&dev->dev, "Error\n");
+	return err;
+}
+
+static const struct usb_device_id id_table[] = {
+	{ USB_DEVICE(EMI62_VENDOR_ID, EMI62_PRODUCT_ID) },
+	{ }                                             /* Terminating entry */
+};
+
+MODULE_DEVICE_TABLE (usb, id_table);
+
+static int emi62_probe(struct usb_interface *intf, const struct usb_device_id *id)
+{
+	struct usb_device *dev = interface_to_usbdev(intf);
+	dev_dbg(&intf->dev, "emi62_probe\n");
+
+	dev_info(&intf->dev, "%s start\n", __func__);
+
+	emi62_load_firmware(dev);
+
+	/* do not return the driver context, let real audio driver do that */
+	return -EIO;
+}
+
+static void emi62_disconnect(struct usb_interface *intf)
+{
+}
+
+static struct usb_driver emi62_driver = {
+	.name		= "emi62 - firmware loader",
+	.probe		= emi62_probe,
+	.disconnect	= emi62_disconnect,
+	.id_table	= id_table,
+};
+
+module_usb_driver(emi62_driver);
+
+MODULE_AUTHOR("Tapio Laxström");
+MODULE_DESCRIPTION("Emagic EMI 6|2m firmware loader.");
+MODULE_LICENSE("GPL");
+
+MODULE_FIRMWARE("emi62/loader.fw");
+MODULE_FIRMWARE("emi62/bitstream.fw");
+MODULE_FIRMWARE(FIRMWARE_FW);
+/* vi:ai:syntax=c:sw=8:ts=8:tw=80
+ */