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, 47 insertions, 0 deletions

diff --git a/drivers/mfd/intel-lpss.h b/drivers/mfd/intel-lpss.h
new file mode 100644
index 000000000..6f8f668f4
--- /dev/null
+++ b/drivers/mfd/intel-lpss.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Intel LPSS core support.
+ *
+ * Copyright (C) 2015, Intel Corporation
+ *
+ * Authors: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
+ *          Mika Westerberg <mika.westerberg@linux.intel.com>
+ */
+
+#ifndef __MFD_INTEL_LPSS_H
+#define __MFD_INTEL_LPSS_H
+
+#include <linux/bits.h>
+#include <linux/pm.h>
+
+/*
+ * Some DSDTs have an unused GEXP ACPI device conflicting with I2C4 resources.
+ * Set to ignore resource conflicts with ACPI declared SystemMemory regions.
+ */
+#define QUIRK_IGNORE_RESOURCE_CONFLICTS BIT(0)
+/*
+ * Some devices have misconfigured clock divider due to a firmware bug.
+ * Set this to force the clock divider to 1:1 ratio.
+ */
+#define QUIRK_CLOCK_DIVIDER_UNITY		BIT(1)
+
+struct device;
+struct resource;
+struct software_node;
+
+struct intel_lpss_platform_info {
+	struct resource *mem;
+	int irq;
+	unsigned int quirks;
+	unsigned long clk_rate;
+	const char *clk_con_id;
+	const struct software_node *swnode;
+};
+
+int intel_lpss_probe(struct device *dev,
+		     const struct intel_lpss_platform_info *info);
+void intel_lpss_remove(struct device *dev);
+
+extern const struct dev_pm_ops intel_lpss_pm_ops;
+
+#endif /* __MFD_INTEL_LPSS_H */