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, 152 insertions, 0 deletions

diff --git a/tools/lib/thermal/thermal.c b/tools/lib/thermal/thermal.c
new file mode 100644
index 000000000..6f02e3539
--- /dev/null
+++ b/tools/lib/thermal/thermal.c
@@ -0,0 +1,152 @@
+// SPDX-License-Identifier: LGPL-2.1+
+// Copyright (C) 2022, Linaro Ltd - Daniel Lezcano <daniel.lezcano@linaro.org>
+#include <stdio.h>
+#include <limits.h>
+#include <thermal.h>
+
+#include "thermal_nl.h"
+
+int for_each_thermal_threshold(struct thermal_threshold *th, cb_th_t cb, void *arg)
+{
+	int i, ret = 0;
+
+	if (!th)
+		return 0;
+
+	for (i = 0; th[i].temperature != INT_MAX; i++)
+		ret |= cb(&th[i], arg);
+
+	return ret;
+}
+
+int for_each_thermal_cdev(struct thermal_cdev *cdev, cb_tc_t cb, void *arg)
+{
+	int i, ret = 0;
+
+	if (!cdev)
+		return 0;
+
+	for (i = 0; cdev[i].id != -1; i++)
+		ret |= cb(&cdev[i], arg);
+
+	return ret;
+}
+
+int for_each_thermal_trip(struct thermal_trip *tt, cb_tt_t cb, void *arg)
+{
+	int i, ret = 0;
+
+	if (!tt)
+		return 0;
+
+	for (i = 0; tt[i].id != -1; i++)
+		ret |= cb(&tt[i], arg);
+
+	return ret;
+}
+
+int for_each_thermal_zone(struct thermal_zone *tz, cb_tz_t cb, void *arg)
+{
+	int i, ret = 0;
+
+	if (!tz)
+		return 0;
+
+	for (i = 0; tz[i].id != -1; i++)
+		ret |= cb(&tz[i], arg);
+
+	return ret;
+}
+
+struct thermal_zone *thermal_zone_find_by_name(struct thermal_zone *tz,
+					       const char *name)
+{
+	int i;
+
+	if (!tz || !name)
+		return NULL;
+
+	for (i = 0; tz[i].id != -1; i++) {
+		if (!strcmp(tz[i].name, name))
+			return &tz[i];
+	}
+
+	return NULL;
+}
+
+struct thermal_zone *thermal_zone_find_by_id(struct thermal_zone *tz, int id)
+{
+	int i;
+
+	if (!tz || id < 0)
+		return NULL;
+
+	for (i = 0; tz[i].id != -1; i++) {
+		if (tz[i].id == id)
+			return &tz[i];
+	}
+
+	return NULL;
+}
+
+static int __thermal_zone_discover(struct thermal_zone *tz, void *th)
+{
+	if (thermal_cmd_get_trip(th, tz) < 0)
+		return -1;
+
+	if (thermal_cmd_threshold_get(th, tz))
+		return -1;
+
+	if (thermal_cmd_get_governor(th, tz))
+		return -1;
+
+	return 0;
+}
+
+struct thermal_zone *thermal_zone_discover(struct thermal_handler *th)
+{
+	struct thermal_zone *tz;
+
+	if (thermal_cmd_get_tz(th, &tz) < 0)
+		return NULL;
+
+	if (for_each_thermal_zone(tz, __thermal_zone_discover, th))
+		return NULL;
+
+	return tz;
+}
+
+void thermal_exit(struct thermal_handler *th)
+{
+	thermal_cmd_exit(th);
+	thermal_events_exit(th);
+	thermal_sampling_exit(th);
+
+	free(th);
+}
+
+struct thermal_handler *thermal_init(struct thermal_ops *ops)
+{
+	struct thermal_handler *th;
+
+	th = malloc(sizeof(*th));
+	if (!th)
+		return NULL;
+	th->ops = ops;
+
+	if (thermal_events_init(th))
+		goto out_free;
+
+	if (thermal_sampling_init(th))
+		goto out_free;
+
+	if (thermal_cmd_init(th))
+		goto out_free;
+
+	return th;
+
+out_free:
+	free(th);
+
+	return NULL;
+}