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, 193 insertions, 0 deletions

diff --git a/drivers/bluetooth/btmrvl_debugfs.c b/drivers/bluetooth/btmrvl_debugfs.c
new file mode 100644
index 000000000..9b3e768c0
--- /dev/null
+++ b/drivers/bluetooth/btmrvl_debugfs.c
@@ -0,0 +1,193 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Marvell Bluetooth driver: debugfs related functions
+ *
+ * Copyright (C) 2009, Marvell International Ltd.
+ **/
+
+#include <linux/debugfs.h>
+#include <linux/slab.h>
+
+#include <net/bluetooth/bluetooth.h>
+#include <net/bluetooth/hci_core.h>
+
+#include "btmrvl_drv.h"
+
+struct btmrvl_debugfs_data {
+	struct dentry *config_dir;
+	struct dentry *status_dir;
+};
+
+static ssize_t btmrvl_hscfgcmd_write(struct file *file,
+			const char __user *ubuf, size_t count, loff_t *ppos)
+{
+	struct btmrvl_private *priv = file->private_data;
+	long result, ret;
+
+	ret = kstrtol_from_user(ubuf, count, 10, &result);
+	if (ret)
+		return ret;
+
+	priv->btmrvl_dev.hscfgcmd = result;
+
+	if (priv->btmrvl_dev.hscfgcmd) {
+		btmrvl_prepare_command(priv);
+		wake_up_interruptible(&priv->main_thread.wait_q);
+	}
+
+	return count;
+}
+
+static ssize_t btmrvl_hscfgcmd_read(struct file *file, char __user *userbuf,
+						size_t count, loff_t *ppos)
+{
+	struct btmrvl_private *priv = file->private_data;
+	char buf[16];
+	int ret;
+
+	ret = snprintf(buf, sizeof(buf) - 1, "%d\n",
+						priv->btmrvl_dev.hscfgcmd);
+
+	return simple_read_from_buffer(userbuf, count, ppos, buf, ret);
+}
+
+static const struct file_operations btmrvl_hscfgcmd_fops = {
+	.read	= btmrvl_hscfgcmd_read,
+	.write	= btmrvl_hscfgcmd_write,
+	.open	= simple_open,
+	.llseek = default_llseek,
+};
+
+static ssize_t btmrvl_pscmd_write(struct file *file, const char __user *ubuf,
+						size_t count, loff_t *ppos)
+{
+	struct btmrvl_private *priv = file->private_data;
+	long result, ret;
+
+	ret = kstrtol_from_user(ubuf, count, 10, &result);
+	if (ret)
+		return ret;
+
+	priv->btmrvl_dev.pscmd = result;
+
+	if (priv->btmrvl_dev.pscmd) {
+		btmrvl_prepare_command(priv);
+		wake_up_interruptible(&priv->main_thread.wait_q);
+	}
+
+	return count;
+
+}
+
+static ssize_t btmrvl_pscmd_read(struct file *file, char __user *userbuf,
+						size_t count, loff_t *ppos)
+{
+	struct btmrvl_private *priv = file->private_data;
+	char buf[16];
+	int ret;
+
+	ret = snprintf(buf, sizeof(buf) - 1, "%d\n", priv->btmrvl_dev.pscmd);
+
+	return simple_read_from_buffer(userbuf, count, ppos, buf, ret);
+}
+
+static const struct file_operations btmrvl_pscmd_fops = {
+	.read = btmrvl_pscmd_read,
+	.write = btmrvl_pscmd_write,
+	.open = simple_open,
+	.llseek = default_llseek,
+};
+
+static ssize_t btmrvl_hscmd_write(struct file *file, const char __user *ubuf,
+						size_t count, loff_t *ppos)
+{
+	struct btmrvl_private *priv = file->private_data;
+	long result, ret;
+
+	ret = kstrtol_from_user(ubuf, count, 10, &result);
+	if (ret)
+		return ret;
+
+	priv->btmrvl_dev.hscmd = result;
+	if (priv->btmrvl_dev.hscmd) {
+		btmrvl_prepare_command(priv);
+		wake_up_interruptible(&priv->main_thread.wait_q);
+	}
+
+	return count;
+}
+
+static ssize_t btmrvl_hscmd_read(struct file *file, char __user *userbuf,
+						size_t count, loff_t *ppos)
+{
+	struct btmrvl_private *priv = file->private_data;
+	char buf[16];
+	int ret;
+
+	ret = snprintf(buf, sizeof(buf) - 1, "%d\n", priv->btmrvl_dev.hscmd);
+
+	return simple_read_from_buffer(userbuf, count, ppos, buf, ret);
+}
+
+static const struct file_operations btmrvl_hscmd_fops = {
+	.read	= btmrvl_hscmd_read,
+	.write	= btmrvl_hscmd_write,
+	.open	= simple_open,
+	.llseek = default_llseek,
+};
+
+void btmrvl_debugfs_init(struct hci_dev *hdev)
+{
+	struct btmrvl_private *priv = hci_get_drvdata(hdev);
+	struct btmrvl_debugfs_data *dbg;
+
+	if (!hdev->debugfs)
+		return;
+
+	dbg = kzalloc_obj(*dbg);
+	priv->debugfs_data = dbg;
+
+	if (!dbg) {
+		BT_ERR("Can not allocate memory for btmrvl_debugfs_data.");
+		return;
+	}
+
+	dbg->config_dir = debugfs_create_dir("config", hdev->debugfs);
+
+	debugfs_create_u8("psmode", 0644, dbg->config_dir,
+			  &priv->btmrvl_dev.psmode);
+	debugfs_create_file("pscmd", 0644, dbg->config_dir,
+			    priv, &btmrvl_pscmd_fops);
+	debugfs_create_x16("gpiogap", 0644, dbg->config_dir,
+			   &priv->btmrvl_dev.gpio_gap);
+	debugfs_create_u8("hsmode", 0644, dbg->config_dir,
+			  &priv->btmrvl_dev.hsmode);
+	debugfs_create_file("hscmd", 0644, dbg->config_dir,
+			    priv, &btmrvl_hscmd_fops);
+	debugfs_create_file("hscfgcmd", 0644, dbg->config_dir,
+			    priv, &btmrvl_hscfgcmd_fops);
+
+	dbg->status_dir = debugfs_create_dir("status", hdev->debugfs);
+	debugfs_create_u8("curpsmode", 0444, dbg->status_dir,
+			  &priv->adapter->psmode);
+	debugfs_create_u8("psstate", 0444, dbg->status_dir,
+			  &priv->adapter->ps_state);
+	debugfs_create_u8("hsstate", 0444, dbg->status_dir,
+			  &priv->adapter->hs_state);
+	debugfs_create_u8("txdnldready", 0444, dbg->status_dir,
+			  &priv->btmrvl_dev.tx_dnld_rdy);
+}
+
+void btmrvl_debugfs_remove(struct hci_dev *hdev)
+{
+	struct btmrvl_private *priv = hci_get_drvdata(hdev);
+	struct btmrvl_debugfs_data *dbg = priv->debugfs_data;
+
+	if (!dbg)
+		return;
+
+	debugfs_remove_recursive(dbg->config_dir);
+	debugfs_remove_recursive(dbg->status_dir);
+
+	kfree(dbg);
+}