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, 212 insertions, 0 deletions

diff --git a/drivers/hid/hid-wiimote-debug.c b/drivers/hid/hid-wiimote-debug.c
new file mode 100644
index 000000000..5f7491778
--- /dev/null
+++ b/drivers/hid/hid-wiimote-debug.c
@@ -0,0 +1,212 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Debug support for HID Nintendo Wii / Wii U peripherals
+ * Copyright (c) 2011-2013 David Herrmann <dh.herrmann@gmail.com>
+ */
+
+/*
+ */
+
+#include <linux/debugfs.h>
+#include <linux/module.h>
+#include <linux/seq_file.h>
+#include <linux/spinlock.h>
+#include <linux/uaccess.h>
+#include "hid-wiimote.h"
+
+struct wiimote_debug {
+	struct wiimote_data *wdata;
+	struct dentry *eeprom;
+	struct dentry *drm;
+};
+
+static ssize_t wiidebug_eeprom_read(struct file *f, char __user *u, size_t s,
+								loff_t *off)
+{
+	struct wiimote_debug *dbg = f->private_data;
+	struct wiimote_data *wdata = dbg->wdata;
+	unsigned long flags;
+	ssize_t ret;
+	char buf[16];
+	__u16 size = 0;
+
+	if (s == 0)
+		return -EINVAL;
+	if (*off > 0xffffff)
+		return 0;
+	if (s > 16)
+		s = 16;
+
+	ret = wiimote_cmd_acquire(wdata);
+	if (ret)
+		return ret;
+
+	spin_lock_irqsave(&wdata->state.lock, flags);
+	wdata->state.cmd_read_size = s;
+	wdata->state.cmd_read_buf = buf;
+	wiimote_cmd_set(wdata, WIIPROTO_REQ_RMEM, *off & 0xffff);
+	wiiproto_req_reeprom(wdata, *off, s);
+	spin_unlock_irqrestore(&wdata->state.lock, flags);
+
+	ret = wiimote_cmd_wait(wdata);
+	if (!ret)
+		size = wdata->state.cmd_read_size;
+
+	spin_lock_irqsave(&wdata->state.lock, flags);
+	wdata->state.cmd_read_buf = NULL;
+	spin_unlock_irqrestore(&wdata->state.lock, flags);
+
+	wiimote_cmd_release(wdata);
+
+	if (ret)
+		return ret;
+	else if (size == 0)
+		return -EIO;
+
+	if (copy_to_user(u, buf, size))
+		return -EFAULT;
+
+	*off += size;
+	ret = size;
+
+	return ret;
+}
+
+static const struct file_operations wiidebug_eeprom_fops = {
+	.owner = THIS_MODULE,
+	.open = simple_open,
+	.read = wiidebug_eeprom_read,
+	.llseek = generic_file_llseek,
+};
+
+static const char *wiidebug_drmmap[] = {
+	[WIIPROTO_REQ_NULL] = "NULL",
+	[WIIPROTO_REQ_DRM_K] = "K",
+	[WIIPROTO_REQ_DRM_KA] = "KA",
+	[WIIPROTO_REQ_DRM_KE] = "KE",
+	[WIIPROTO_REQ_DRM_KAI] = "KAI",
+	[WIIPROTO_REQ_DRM_KEE] = "KEE",
+	[WIIPROTO_REQ_DRM_KAE] = "KAE",
+	[WIIPROTO_REQ_DRM_KIE] = "KIE",
+	[WIIPROTO_REQ_DRM_KAIE] = "KAIE",
+	[WIIPROTO_REQ_DRM_E] = "E",
+	[WIIPROTO_REQ_DRM_SKAI1] = "SKAI1",
+	[WIIPROTO_REQ_DRM_SKAI2] = "SKAI2",
+	[WIIPROTO_REQ_MAX] = NULL
+};
+
+static int wiidebug_drm_show(struct seq_file *f, void *p)
+{
+	struct wiimote_debug *dbg = f->private;
+	const char *str = NULL;
+	unsigned long flags;
+	__u8 drm;
+
+	spin_lock_irqsave(&dbg->wdata->state.lock, flags);
+	drm = dbg->wdata->state.drm;
+	spin_unlock_irqrestore(&dbg->wdata->state.lock, flags);
+
+	if (drm < WIIPROTO_REQ_MAX)
+		str = wiidebug_drmmap[drm];
+	if (!str)
+		str = "unknown";
+
+	seq_printf(f, "%s\n", str);
+
+	return 0;
+}
+
+static int wiidebug_drm_open(struct inode *i, struct file *f)
+{
+	return single_open(f, wiidebug_drm_show, i->i_private);
+}
+
+static ssize_t wiidebug_drm_write(struct file *f, const char __user *u,
+							size_t s, loff_t *off)
+{
+	struct seq_file *sf = f->private_data;
+	struct wiimote_debug *dbg = sf->private;
+	unsigned long flags;
+	char buf[16];
+	ssize_t len;
+	int i;
+
+	if (s == 0)
+		return -EINVAL;
+
+	len = min((size_t) 15, s);
+	if (copy_from_user(buf, u, len))
+		return -EFAULT;
+
+	buf[len] = 0;
+
+	for (i = 0; i < WIIPROTO_REQ_MAX; ++i) {
+		if (!wiidebug_drmmap[i])
+			continue;
+		if (!strcasecmp(buf, wiidebug_drmmap[i]))
+			break;
+	}
+
+	if (i == WIIPROTO_REQ_MAX)
+		i = simple_strtoul(buf, NULL, 16);
+
+	spin_lock_irqsave(&dbg->wdata->state.lock, flags);
+	dbg->wdata->state.flags &= ~WIIPROTO_FLAG_DRM_LOCKED;
+	wiiproto_req_drm(dbg->wdata, (__u8) i);
+	if (i != WIIPROTO_REQ_NULL)
+		dbg->wdata->state.flags |= WIIPROTO_FLAG_DRM_LOCKED;
+	spin_unlock_irqrestore(&dbg->wdata->state.lock, flags);
+
+	return len;
+}
+
+static const struct file_operations wiidebug_drm_fops = {
+	.owner = THIS_MODULE,
+	.open = wiidebug_drm_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.write = wiidebug_drm_write,
+	.release = single_release,
+};
+
+int wiidebug_init(struct wiimote_data *wdata)
+{
+	struct wiimote_debug *dbg;
+	unsigned long flags;
+
+	dbg = kzalloc_obj(*dbg);
+	if (!dbg)
+		return -ENOMEM;
+
+	dbg->wdata = wdata;
+
+	dbg->eeprom = debugfs_create_file("eeprom", S_IRUSR,
+		dbg->wdata->hdev->debug_dir, dbg, &wiidebug_eeprom_fops);
+
+	dbg->drm = debugfs_create_file("drm", S_IRUSR,
+			dbg->wdata->hdev->debug_dir, dbg, &wiidebug_drm_fops);
+
+	spin_lock_irqsave(&wdata->state.lock, flags);
+	wdata->debug = dbg;
+	spin_unlock_irqrestore(&wdata->state.lock, flags);
+
+	return 0;
+
+}
+
+void wiidebug_deinit(struct wiimote_data *wdata)
+{
+	struct wiimote_debug *dbg = wdata->debug;
+	unsigned long flags;
+
+	if (!dbg)
+		return;
+
+	spin_lock_irqsave(&wdata->state.lock, flags);
+	wdata->debug = NULL;
+	spin_unlock_irqrestore(&wdata->state.lock, flags);
+
+	debugfs_remove(dbg->drm);
+	debugfs_remove(dbg->eeprom);
+	kfree(dbg);
+}