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, 244 insertions, 0 deletions

diff --git a/drivers/media/rc/ir-sharp-decoder.c b/drivers/media/rc/ir-sharp-decoder.c
new file mode 100644
index 000000000..3311099cb
--- /dev/null
+++ b/drivers/media/rc/ir-sharp-decoder.c
@@ -0,0 +1,244 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* ir-sharp-decoder.c - handle Sharp IR Pulse/Space protocol
+ *
+ * Copyright (C) 2013-2014 Imagination Technologies Ltd.
+ *
+ * Based on NEC decoder:
+ * Copyright (C) 2010 by Mauro Carvalho Chehab
+ */
+
+#include <linux/bitrev.h>
+#include <linux/module.h>
+#include "rc-core-priv.h"
+
+#define SHARP_NBITS		15
+#define SHARP_UNIT		40  /* us */
+#define SHARP_BIT_PULSE		(8    * SHARP_UNIT) /* 320us */
+#define SHARP_BIT_0_PERIOD	(25   * SHARP_UNIT) /* 1ms (680us space) */
+#define SHARP_BIT_1_PERIOD	(50   * SHARP_UNIT) /* 2ms (1680us space) */
+#define SHARP_BIT_0_SPACE	(17   * SHARP_UNIT) /* 680us space */
+#define SHARP_BIT_1_SPACE	(42   * SHARP_UNIT) /* 1680us space */
+#define SHARP_ECHO_SPACE	(1000 * SHARP_UNIT) /* 40 ms */
+#define SHARP_TRAILER_SPACE	(125  * SHARP_UNIT) /* 5 ms (even longer) */
+
+enum sharp_state {
+	STATE_INACTIVE,
+	STATE_BIT_PULSE,
+	STATE_BIT_SPACE,
+	STATE_TRAILER_PULSE,
+	STATE_ECHO_SPACE,
+	STATE_TRAILER_SPACE,
+};
+
+/**
+ * ir_sharp_decode() - Decode one Sharp 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_sharp_decode(struct rc_dev *dev, struct ir_raw_event ev)
+{
+	struct sharp_dec *data = &dev->raw->sharp;
+	u32 msg, echo, address, command, scancode;
+
+	if (!is_timing_event(ev)) {
+		if (ev.overflow)
+			data->state = STATE_INACTIVE;
+		return 0;
+	}
+
+	dev_dbg(&dev->dev, "Sharp decode started at state %d (%uus %s)\n",
+		data->state, ev.duration, TO_STR(ev.pulse));
+
+	switch (data->state) {
+
+	case STATE_INACTIVE:
+		if (!ev.pulse)
+			break;
+
+		if (!eq_margin(ev.duration, SHARP_BIT_PULSE,
+			       SHARP_BIT_PULSE / 2))
+			break;
+
+		data->count = 0;
+		data->pulse_len = ev.duration;
+		data->state = STATE_BIT_SPACE;
+		return 0;
+
+	case STATE_BIT_PULSE:
+		if (!ev.pulse)
+			break;
+
+		if (!eq_margin(ev.duration, SHARP_BIT_PULSE,
+			       SHARP_BIT_PULSE / 2))
+			break;
+
+		data->pulse_len = ev.duration;
+		data->state = STATE_BIT_SPACE;
+		return 0;
+
+	case STATE_BIT_SPACE:
+		if (ev.pulse)
+			break;
+
+		data->bits <<= 1;
+		if (eq_margin(data->pulse_len + ev.duration, SHARP_BIT_1_PERIOD,
+			      SHARP_BIT_PULSE * 2))
+			data->bits |= 1;
+		else if (!eq_margin(data->pulse_len + ev.duration,
+				    SHARP_BIT_0_PERIOD, SHARP_BIT_PULSE * 2))
+			break;
+		data->count++;
+
+		if (data->count == SHARP_NBITS ||
+		    data->count == SHARP_NBITS * 2)
+			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, SHARP_BIT_PULSE,
+			       SHARP_BIT_PULSE / 2))
+			break;
+
+		if (data->count == SHARP_NBITS) {
+			/* exp,chk bits should be 1,0 */
+			if ((data->bits & 0x3) != 0x2 &&
+			/* DENON variant, both chk bits 0 */
+			    (data->bits & 0x3) != 0x0)
+				break;
+			data->state = STATE_ECHO_SPACE;
+		} else {
+			data->state = STATE_TRAILER_SPACE;
+		}
+		return 0;
+
+	case STATE_ECHO_SPACE:
+		if (ev.pulse)
+			break;
+
+		if (!eq_margin(ev.duration, SHARP_ECHO_SPACE,
+			       SHARP_ECHO_SPACE / 4))
+			break;
+
+		data->state = STATE_BIT_PULSE;
+
+		return 0;
+
+	case STATE_TRAILER_SPACE:
+		if (ev.pulse)
+			break;
+
+		if (!geq_margin(ev.duration, SHARP_TRAILER_SPACE,
+				SHARP_BIT_PULSE / 2))
+			break;
+
+		/* Validate - command, ext, chk should be inverted in 2nd */
+		msg = (data->bits >> 15) & 0x7fff;
+		echo = data->bits & 0x7fff;
+		if ((msg ^ echo) != 0x3ff) {
+			dev_dbg(&dev->dev,
+				"Sharp checksum error: received 0x%04x, 0x%04x\n",
+				msg, echo);
+			break;
+		}
+
+		address = bitrev8((msg >> 7) & 0xf8);
+		command = bitrev8((msg >> 2) & 0xff);
+
+		scancode = address << 8 | command;
+		dev_dbg(&dev->dev, "Sharp scancode 0x%04x\n", scancode);
+
+		rc_keydown(dev, RC_PROTO_SHARP, scancode, 0);
+		data->state = STATE_INACTIVE;
+		return 0;
+	}
+
+	dev_dbg(&dev->dev, "Sharp decode failed at count %d state %d (%uus %s)\n",
+		data->count, data->state, ev.duration, TO_STR(ev.pulse));
+	data->state = STATE_INACTIVE;
+	return -EINVAL;
+}
+
+static const struct ir_raw_timings_pd ir_sharp_timings = {
+	.header_pulse  = 0,
+	.header_space  = 0,
+	.bit_pulse     = SHARP_BIT_PULSE,
+	.bit_space[0]  = SHARP_BIT_0_SPACE,
+	.bit_space[1]  = SHARP_BIT_1_SPACE,
+	.trailer_pulse = SHARP_BIT_PULSE,
+	.trailer_space = SHARP_ECHO_SPACE,
+	.msb_first     = 1,
+};
+
+/**
+ * ir_sharp_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_sharp_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;
+
+	raw = (((bitrev8(scancode >> 8) >> 3) << 8) & 0x1f00) |
+		bitrev8(scancode);
+	ret = ir_raw_gen_pd(&e, max, &ir_sharp_timings, SHARP_NBITS,
+			    (raw << 2) | 2);
+	if (ret < 0)
+		return ret;
+
+	max -= ret;
+
+	raw = (((bitrev8(scancode >> 8) >> 3) << 8) & 0x1f00) |
+		bitrev8(~scancode);
+	ret = ir_raw_gen_pd(&e, max, &ir_sharp_timings, SHARP_NBITS,
+			    (raw << 2) | 1);
+	if (ret < 0)
+		return ret;
+
+	return e - events;
+}
+
+static struct ir_raw_handler sharp_handler = {
+	.protocols	= RC_PROTO_BIT_SHARP,
+	.decode		= ir_sharp_decode,
+	.encode		= ir_sharp_encode,
+	.carrier	= 38000,
+	.min_timeout	= SHARP_ECHO_SPACE + SHARP_ECHO_SPACE / 4,
+};
+
+static int __init ir_sharp_decode_init(void)
+{
+	ir_raw_handler_register(&sharp_handler);
+
+	pr_info("IR Sharp protocol handler initialized\n");
+	return 0;
+}
+
+static void __exit ir_sharp_decode_exit(void)
+{
+	ir_raw_handler_unregister(&sharp_handler);
+}
+
+module_init(ir_sharp_decode_init);
+module_exit(ir_sharp_decode_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("James Hogan <jhogan@kernel.org>");
+MODULE_DESCRIPTION("Sharp IR protocol decoder");