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, 229 insertions, 0 deletions

diff --git a/drivers/media/rc/ir-jvc-decoder.c b/drivers/media/rc/ir-jvc-decoder.c
new file mode 100644
index 000000000..8b10954d2
--- /dev/null
+++ b/drivers/media/rc/ir-jvc-decoder.c
@@ -0,0 +1,229 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* ir-jvc-decoder.c - handle JVC IR Pulse/Space protocol
+ *
+ * Copyright (C) 2010 by David Härdeman <david@hardeman.nu>
+ */
+
+#include <linux/bitrev.h>
+#include <linux/module.h>
+#include "rc-core-priv.h"
+
+#define JVC_NBITS		16		/* dev(8) + func(8) */
+#define JVC_UNIT		525		/* us */
+#define JVC_HEADER_PULSE	(16 * JVC_UNIT) /* lack of header -> repeat */
+#define JVC_HEADER_SPACE	(8  * JVC_UNIT)
+#define JVC_BIT_PULSE		(1  * JVC_UNIT)
+#define JVC_BIT_0_SPACE		(1  * JVC_UNIT)
+#define JVC_BIT_1_SPACE		(3  * JVC_UNIT)
+#define JVC_TRAILER_PULSE	(1  * JVC_UNIT)
+#define	JVC_TRAILER_SPACE	(35 * JVC_UNIT)
+
+enum jvc_state {
+	STATE_INACTIVE,
+	STATE_HEADER_SPACE,
+	STATE_BIT_PULSE,
+	STATE_BIT_SPACE,
+	STATE_TRAILER_PULSE,
+	STATE_TRAILER_SPACE,
+	STATE_CHECK_REPEAT,
+};
+
+/**
+ * ir_jvc_decode() - Decode one JVC pulse or space
+ * @dev:	the struct rc_dev descriptor of the device
+ * @ev:   the struct ir_raw_event descriptor of the pulse/space
+ *
+ * This function returns -EINVAL if the pulse violates the state machine
+ */
+static int ir_jvc_decode(struct rc_dev *dev, struct ir_raw_event ev)
+{
+	struct jvc_dec *data = &dev->raw->jvc;
+
+	if (!is_timing_event(ev)) {
+		if (ev.overflow)
+			data->state = STATE_INACTIVE;
+		return 0;
+	}
+
+	if (!geq_margin(ev.duration, JVC_UNIT, JVC_UNIT / 2))
+		goto out;
+
+	dev_dbg(&dev->dev, "JVC decode started at state %d (%uus %s)\n",
+		data->state, ev.duration, TO_STR(ev.pulse));
+
+again:
+	switch (data->state) {
+
+	case STATE_INACTIVE:
+		if (!ev.pulse)
+			break;
+
+		if (!eq_margin(ev.duration, JVC_HEADER_PULSE, JVC_UNIT / 2))
+			break;
+
+		data->count = 0;
+		data->first = true;
+		data->toggle = !data->toggle;
+		data->state = STATE_HEADER_SPACE;
+		return 0;
+
+	case STATE_HEADER_SPACE:
+		if (ev.pulse)
+			break;
+
+		if (!eq_margin(ev.duration, JVC_HEADER_SPACE, JVC_UNIT / 2))
+			break;
+
+		data->state = STATE_BIT_PULSE;
+		return 0;
+
+	case STATE_BIT_PULSE:
+		if (!ev.pulse)
+			break;
+
+		if (!eq_margin(ev.duration, JVC_BIT_PULSE, JVC_UNIT / 2))
+			break;
+
+		data->state = STATE_BIT_SPACE;
+		return 0;
+
+	case STATE_BIT_SPACE:
+		if (ev.pulse)
+			break;
+
+		data->bits <<= 1;
+		if (eq_margin(ev.duration, JVC_BIT_1_SPACE, JVC_UNIT / 2)) {
+			data->bits |= 1;
+			decrease_duration(&ev, JVC_BIT_1_SPACE);
+		} else if (eq_margin(ev.duration, JVC_BIT_0_SPACE, JVC_UNIT / 2))
+			decrease_duration(&ev, JVC_BIT_0_SPACE);
+		else
+			break;
+		data->count++;
+
+		if (data->count == JVC_NBITS)
+			data->state = STATE_TRAILER_PULSE;
+		else
+			data->state = STATE_BIT_PULSE;
+		return 0;
+
+	case STATE_TRAILER_PULSE:
+		if (!ev.pulse)
+			break;
+
+		if (!eq_margin(ev.duration, JVC_TRAILER_PULSE, JVC_UNIT / 2))
+			break;
+
+		data->state = STATE_TRAILER_SPACE;
+		return 0;
+
+	case STATE_TRAILER_SPACE:
+		if (ev.pulse)
+			break;
+
+		if (!geq_margin(ev.duration, JVC_TRAILER_SPACE, JVC_UNIT / 2))
+			break;
+
+		if (data->first) {
+			u32 scancode;
+			scancode = (bitrev8((data->bits >> 8) & 0xff) << 8) |
+				   (bitrev8((data->bits >> 0) & 0xff) << 0);
+			dev_dbg(&dev->dev, "JVC scancode 0x%04x\n", scancode);
+			rc_keydown(dev, RC_PROTO_JVC, scancode, data->toggle);
+			data->first = false;
+			data->old_bits = data->bits;
+		} else if (data->bits == data->old_bits) {
+			dev_dbg(&dev->dev, "JVC repeat\n");
+			rc_repeat(dev);
+		} else {
+			dev_dbg(&dev->dev, "JVC invalid repeat msg\n");
+			break;
+		}
+
+		data->count = 0;
+		data->state = STATE_CHECK_REPEAT;
+		return 0;
+
+	case STATE_CHECK_REPEAT:
+		if (!ev.pulse)
+			break;
+
+		if (eq_margin(ev.duration, JVC_HEADER_PULSE, JVC_UNIT / 2))
+			data->state = STATE_INACTIVE;
+  else
+			data->state = STATE_BIT_PULSE;
+		goto again;
+	}
+
+out:
+	dev_dbg(&dev->dev, "JVC decode failed at state %d (%uus %s)\n",
+		data->state, ev.duration, TO_STR(ev.pulse));
+	data->state = STATE_INACTIVE;
+	return -EINVAL;
+}
+
+static const struct ir_raw_timings_pd ir_jvc_timings = {
+	.header_pulse  = JVC_HEADER_PULSE,
+	.header_space  = JVC_HEADER_SPACE,
+	.bit_pulse     = JVC_BIT_PULSE,
+	.bit_space[0]  = JVC_BIT_0_SPACE,
+	.bit_space[1]  = JVC_BIT_1_SPACE,
+	.trailer_pulse = JVC_TRAILER_PULSE,
+	.trailer_space = JVC_TRAILER_SPACE,
+	.msb_first     = 1,
+};
+
+/**
+ * ir_jvc_encode() - Encode a scancode as a stream of raw events
+ *
+ * @protocol:	protocol to encode
+ * @scancode:	scancode to encode
+ * @events:	array of raw ir events to write into
+ * @max:	maximum size of @events
+ *
+ * Returns:	The number of events written.
+ *		-ENOBUFS if there isn't enough space in the array to fit the
+ *		encoding. In this case all @max events will have been written.
+ */
+static int ir_jvc_encode(enum rc_proto protocol, u32 scancode,
+			 struct ir_raw_event *events, unsigned int max)
+{
+	struct ir_raw_event *e = events;
+	int ret;
+	u32 raw = (bitrev8((scancode >> 8) & 0xff) << 8) |
+		  (bitrev8((scancode >> 0) & 0xff) << 0);
+
+	ret = ir_raw_gen_pd(&e, max, &ir_jvc_timings, JVC_NBITS, raw);
+	if (ret < 0)
+		return ret;
+
+	return e - events;
+}
+
+static struct ir_raw_handler jvc_handler = {
+	.protocols	= RC_PROTO_BIT_JVC,
+	.decode		= ir_jvc_decode,
+	.encode		= ir_jvc_encode,
+	.carrier	= 38000,
+	.min_timeout	= JVC_TRAILER_SPACE,
+};
+
+static int __init ir_jvc_decode_init(void)
+{
+	ir_raw_handler_register(&jvc_handler);
+
+	printk(KERN_INFO "IR JVC protocol handler initialized\n");
+	return 0;
+}
+
+static void __exit ir_jvc_decode_exit(void)
+{
+	ir_raw_handler_unregister(&jvc_handler);
+}
+
+module_init(ir_jvc_decode_init);
+module_exit(ir_jvc_decode_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
+MODULE_DESCRIPTION("JVC IR protocol decoder");