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, 65 insertions, 0 deletions

diff --git a/drivers/reset/sti/reset-syscfg.h b/drivers/reset/sti/reset-syscfg.h
new file mode 100644
index 000000000..4e3e69de1
--- /dev/null
+++ b/drivers/reset/sti/reset-syscfg.h
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2013 STMicroelectronics (R&D) Limited
+ * Author: Stephen Gallimore <stephen.gallimore@st.com>
+ */
+#ifndef __STI_RESET_SYSCFG_H
+#define __STI_RESET_SYSCFG_H
+
+#include <linux/device.h>
+#include <linux/regmap.h>
+#include <linux/reset-controller.h>
+
+/**
+ * Reset channel description for a system configuration register based
+ * reset controller.
+ *
+ * @compatible: Compatible string of the syscon regmap containing this
+ *              channel's control and ack (status) bits.
+ * @reset: Regmap field description of the channel's reset bit.
+ * @ack: Regmap field description of the channel's acknowledge bit.
+ */
+struct syscfg_reset_channel_data {
+	const char *compatible;
+	struct reg_field reset;
+	struct reg_field ack;
+};
+
+#define _SYSCFG_RST_CH(_c, _rr, _rb, _ar, _ab)		\
+	{ .compatible	= _c,				\
+	  .reset	= REG_FIELD(_rr, _rb, _rb),	\
+	  .ack		= REG_FIELD(_ar, _ab, _ab), }
+
+#define _SYSCFG_RST_CH_NO_ACK(_c, _rr, _rb)		\
+	{ .compatible	= _c,			\
+	  .reset	= REG_FIELD(_rr, _rb, _rb), }
+
+/**
+ * Description of a system configuration register based reset controller.
+ *
+ * @wait_for_ack: The controller will wait for reset assert and de-assert to
+ *                be "ack'd" in a channel's ack field.
+ * @active_low: Are the resets in this controller active low, i.e. clearing
+ *              the reset bit puts the hardware into reset.
+ * @nr_channels: The number of reset channels in this controller.
+ * @channels: An array of reset channel descriptions.
+ */
+struct syscfg_reset_controller_data {
+	bool wait_for_ack;
+	bool active_low;
+	int nr_channels;
+	const struct syscfg_reset_channel_data *channels;
+};
+
+/**
+ * syscfg_reset_probe(): platform device probe function used by syscfg
+ *                       reset controller drivers. This registers a reset
+ *                       controller configured by the OF match data for
+ *                       the compatible device which should be of type
+ *                       "struct syscfg_reset_controller_data".
+ *
+ * @pdev: platform device
+ */
+int syscfg_reset_probe(struct platform_device *pdev);
+
+#endif /* __STI_RESET_SYSCFG_H */