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, 89 insertions, 0 deletions

diff --git a/drivers/macintosh/windfarm_pid.h b/drivers/macintosh/windfarm_pid.h
new file mode 100644
index 000000000..335613a20
--- /dev/null
+++ b/drivers/macintosh/windfarm_pid.h
@@ -0,0 +1,89 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _WINDFARM_PID_H
+#define _WINDFARM_PID_H
+
+/*
+ * Windfarm PowerMac thermal control. Generic PID helpers
+ *
+ * (c) Copyright 2005 Benjamin Herrenschmidt, IBM Corp.
+ *                    <benh@kernel.crashing.org>
+ *
+ * This is a pair of generic PID helpers that can be used by
+ * control loops. One is the basic PID implementation, the
+ * other one is more specifically tailored to the loops used
+ * for CPU control with 2 input sample types (temp and power)
+ */
+
+/*
+ * *** Simple PID ***
+ */
+
+#define WF_PID_MAX_HISTORY	32
+
+/* This parameter array is passed to the PID algorithm. Currently,
+ * we don't support changing parameters on the fly as it's not needed
+ * but could be implemented (with necessary adjustment of the history
+ * buffer
+ */
+struct wf_pid_param {
+	int	interval;	/* Interval between samples in seconds */
+	int	history_len;	/* Size of history buffer */
+	int	additive;	/* 1: target relative to previous value */
+	s32	gd, gp, gr;	/* PID gains */
+	s32	itarget;	/* PID input target */
+	s32	min,max;	/* min and max target values */
+};
+
+struct wf_pid_state {
+	int	first;				/* first run of the loop */
+	int	index; 				/* index of current sample */
+	s32	target;				/* current target value */
+	s32	samples[WF_PID_MAX_HISTORY];	/* samples history buffer */
+	s32	errors[WF_PID_MAX_HISTORY];	/* error history buffer */
+
+	struct wf_pid_param param;
+};
+
+extern void wf_pid_init(struct wf_pid_state *st, struct wf_pid_param *param);
+extern s32 wf_pid_run(struct wf_pid_state *st, s32 sample);
+
+
+/*
+ * *** CPU PID ***
+ */
+
+#define WF_CPU_PID_MAX_HISTORY	32
+
+/* This parameter array is passed to the CPU PID algorithm. Currently,
+ * we don't support changing parameters on the fly as it's not needed
+ * but could be implemented (with necessary adjustment of the history
+ * buffer
+ */
+struct wf_cpu_pid_param {
+	int	interval;	/* Interval between samples in seconds */
+	int	history_len;	/* Size of history buffer */
+	s32	gd, gp, gr;	/* PID gains */
+	s32	pmaxadj;	/* PID max power adjust */
+	s32	ttarget;	/* PID input target */
+	s32	tmax;		/* PID input max */
+	s32	min,max;	/* min and max target values */
+};
+
+struct wf_cpu_pid_state {
+	int	first;				/* first run of the loop */
+	int	index; 				/* index of current power */
+	int	tindex; 			/* index of current temp */
+	s32	target;				/* current target value */
+	s32	last_delta;			/* last Tactual - Ttarget */
+	s32	powers[WF_PID_MAX_HISTORY];	/* power history buffer */
+	s32	errors[WF_PID_MAX_HISTORY];	/* error history buffer */
+	s32	temps[2];			/* temp. history buffer */
+
+	struct wf_cpu_pid_param param;
+};
+
+extern void wf_cpu_pid_init(struct wf_cpu_pid_state *st,
+			    struct wf_cpu_pid_param *param);
+extern s32 wf_cpu_pid_run(struct wf_cpu_pid_state *st, s32 power, s32 temp);
+
+#endif /* _WINDFARM_PID_H */