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, 351 insertions, 0 deletions

diff --git a/sound/firewire/cmp.c b/sound/firewire/cmp.c
new file mode 100644
index 000000000..b2b76c7c7
--- /dev/null
+++ b/sound/firewire/cmp.c
@@ -0,0 +1,351 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Connection Management Procedures (IEC 61883-1) helper functions
+ *
+ * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
+ */
+
+#include <linux/device.h>
+#include <linux/firewire.h>
+#include <linux/firewire-constants.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include "lib.h"
+#include "iso-resources.h"
+#include "cmp.h"
+
+/* MPR common fields */
+#define MPR_SPEED_MASK		0xc0000000
+#define MPR_SPEED_SHIFT		30
+#define MPR_XSPEED_MASK		0x00000060
+#define MPR_XSPEED_SHIFT	5
+#define MPR_PLUGS_MASK		0x0000001f
+
+/* PCR common fields */
+#define PCR_ONLINE		0x80000000
+#define PCR_BCAST_CONN		0x40000000
+#define PCR_P2P_CONN_MASK	0x3f000000
+#define PCR_P2P_CONN_SHIFT	24
+#define PCR_CHANNEL_MASK	0x003f0000
+#define PCR_CHANNEL_SHIFT	16
+
+/* oPCR specific fields */
+#define OPCR_XSPEED_MASK	0x00C00000
+#define OPCR_XSPEED_SHIFT	22
+#define OPCR_SPEED_MASK		0x0000C000
+#define OPCR_SPEED_SHIFT	14
+#define OPCR_OVERHEAD_ID_MASK	0x00003C00
+#define OPCR_OVERHEAD_ID_SHIFT	10
+
+enum bus_reset_handling {
+	ABORT_ON_BUS_RESET,
+	SUCCEED_ON_BUS_RESET,
+};
+
+static __printf(2, 3)
+void cmp_error(struct cmp_connection *c, const char *fmt, ...)
+{
+	va_list va;
+
+	va_start(va, fmt);
+	dev_err(&c->resources.unit->device, "%cPCR%u: %pV",
+		(c->direction == CMP_INPUT) ? 'i' : 'o',
+		c->pcr_index, &(struct va_format){ fmt, &va });
+	va_end(va);
+}
+
+static u64 mpr_address(struct cmp_connection *c)
+{
+	if (c->direction == CMP_INPUT)
+		return CSR_REGISTER_BASE + CSR_IMPR;
+	else
+		return CSR_REGISTER_BASE + CSR_OMPR;
+}
+
+static u64 pcr_address(struct cmp_connection *c)
+{
+	if (c->direction == CMP_INPUT)
+		return CSR_REGISTER_BASE + CSR_IPCR(c->pcr_index);
+	else
+		return CSR_REGISTER_BASE + CSR_OPCR(c->pcr_index);
+}
+
+static int pcr_modify(struct cmp_connection *c,
+		      __be32 (*modify)(struct cmp_connection *c, __be32 old),
+		      int (*check)(struct cmp_connection *c, __be32 pcr),
+		      enum bus_reset_handling bus_reset_handling)
+{
+	__be32 old_arg, buffer[2];
+	int err;
+
+	buffer[0] = c->last_pcr_value;
+	for (;;) {
+		old_arg = buffer[0];
+		buffer[1] = modify(c, buffer[0]);
+
+		err = snd_fw_transaction(
+				c->resources.unit, TCODE_LOCK_COMPARE_SWAP,
+				pcr_address(c), buffer, 8,
+				FW_FIXED_GENERATION | c->resources.generation);
+
+		if (err < 0) {
+			if (err == -EAGAIN &&
+			    bus_reset_handling == SUCCEED_ON_BUS_RESET)
+				err = 0;
+			return err;
+		}
+
+		if (buffer[0] == old_arg) /* success? */
+			break;
+
+		if (check) {
+			err = check(c, buffer[0]);
+			if (err < 0)
+				return err;
+		}
+	}
+	c->last_pcr_value = buffer[1];
+
+	return 0;
+}
+
+
+/**
+ * cmp_connection_init - initializes a connection manager
+ * @c: the connection manager to initialize
+ * @unit: a unit of the target device
+ * @direction: input or output
+ * @pcr_index: the index of the iPCR/oPCR on the target device
+ */
+int cmp_connection_init(struct cmp_connection *c,
+			struct fw_unit *unit,
+			enum cmp_direction direction,
+			unsigned int pcr_index)
+{
+	__be32 mpr_be;
+	u32 mpr;
+	int err;
+
+	c->direction = direction;
+	err = snd_fw_transaction(unit, TCODE_READ_QUADLET_REQUEST,
+				 mpr_address(c), &mpr_be, 4, 0);
+	if (err < 0)
+		return err;
+	mpr = be32_to_cpu(mpr_be);
+
+	if (pcr_index >= (mpr & MPR_PLUGS_MASK))
+		return -EINVAL;
+
+	err = fw_iso_resources_init(&c->resources, unit);
+	if (err < 0)
+		return err;
+
+	c->connected = false;
+	mutex_init(&c->mutex);
+	c->last_pcr_value = cpu_to_be32(0x80000000);
+	c->pcr_index = pcr_index;
+	c->max_speed = (mpr & MPR_SPEED_MASK) >> MPR_SPEED_SHIFT;
+	if (c->max_speed == SCODE_BETA)
+		c->max_speed += (mpr & MPR_XSPEED_MASK) >> MPR_XSPEED_SHIFT;
+
+	return 0;
+}
+EXPORT_SYMBOL(cmp_connection_init);
+
+/**
+ * cmp_connection_check_used - check connection is already esablished or not
+ * @c: the connection manager to be checked
+ * @used: the pointer to store the result of checking the connection
+ */
+int cmp_connection_check_used(struct cmp_connection *c, bool *used)
+{
+	__be32 pcr;
+	int err;
+
+	err = snd_fw_transaction(
+			c->resources.unit, TCODE_READ_QUADLET_REQUEST,
+			pcr_address(c), &pcr, 4, 0);
+	if (err >= 0)
+		*used = !!(pcr & cpu_to_be32(PCR_BCAST_CONN |
+					     PCR_P2P_CONN_MASK));
+
+	return err;
+}
+EXPORT_SYMBOL(cmp_connection_check_used);
+
+/**
+ * cmp_connection_destroy - free connection manager resources
+ * @c: the connection manager
+ */
+void cmp_connection_destroy(struct cmp_connection *c)
+{
+	WARN_ON(c->connected);
+	mutex_destroy(&c->mutex);
+	fw_iso_resources_destroy(&c->resources);
+}
+EXPORT_SYMBOL(cmp_connection_destroy);
+
+int cmp_connection_reserve(struct cmp_connection *c,
+			   unsigned int max_payload_bytes)
+{
+	guard(mutex)(&c->mutex);
+
+	if (WARN_ON(c->resources.allocated))
+		return -EBUSY;
+
+	c->speed = min(c->max_speed,
+		       fw_parent_device(c->resources.unit)->max_speed);
+
+	return fw_iso_resources_allocate(&c->resources, max_payload_bytes,
+					 c->speed);
+}
+EXPORT_SYMBOL(cmp_connection_reserve);
+
+void cmp_connection_release(struct cmp_connection *c)
+{
+	guard(mutex)(&c->mutex);
+	fw_iso_resources_free(&c->resources);
+}
+EXPORT_SYMBOL(cmp_connection_release);
+
+static __be32 ipcr_set_modify(struct cmp_connection *c, __be32 ipcr)
+{
+	ipcr &= ~cpu_to_be32(PCR_BCAST_CONN |
+			     PCR_P2P_CONN_MASK |
+			     PCR_CHANNEL_MASK);
+	ipcr |= cpu_to_be32(1 << PCR_P2P_CONN_SHIFT);
+	ipcr |= cpu_to_be32(c->resources.channel << PCR_CHANNEL_SHIFT);
+
+	return ipcr;
+}
+
+static int get_overhead_id(struct cmp_connection *c)
+{
+	int id;
+
+	/*
+	 * apply "oPCR overhead ID encoding"
+	 * the encoding table can convert up to 512.
+	 * here the value over 512 is converted as the same way as 512.
+	 */
+	for (id = 1; id < 16; id++) {
+		if (c->resources.bandwidth_overhead < (id << 5))
+			break;
+	}
+	if (id == 16)
+		id = 0;
+
+	return id;
+}
+
+static __be32 opcr_set_modify(struct cmp_connection *c, __be32 opcr)
+{
+	unsigned int spd, xspd;
+
+	/* generate speed and extended speed field value */
+	if (c->speed > SCODE_400) {
+		spd  = SCODE_800;
+		xspd = c->speed - SCODE_800;
+	} else {
+		spd = c->speed;
+		xspd = 0;
+	}
+
+	opcr &= ~cpu_to_be32(PCR_BCAST_CONN |
+			     PCR_P2P_CONN_MASK |
+			     OPCR_XSPEED_MASK |
+			     PCR_CHANNEL_MASK |
+			     OPCR_SPEED_MASK |
+			     OPCR_OVERHEAD_ID_MASK);
+	opcr |= cpu_to_be32(1 << PCR_P2P_CONN_SHIFT);
+	opcr |= cpu_to_be32(xspd << OPCR_XSPEED_SHIFT);
+	opcr |= cpu_to_be32(c->resources.channel << PCR_CHANNEL_SHIFT);
+	opcr |= cpu_to_be32(spd << OPCR_SPEED_SHIFT);
+	opcr |= cpu_to_be32(get_overhead_id(c) << OPCR_OVERHEAD_ID_SHIFT);
+
+	return opcr;
+}
+
+static int pcr_set_check(struct cmp_connection *c, __be32 pcr)
+{
+	if (pcr & cpu_to_be32(PCR_BCAST_CONN |
+			      PCR_P2P_CONN_MASK)) {
+		cmp_error(c, "plug is already in use\n");
+		return -EBUSY;
+	}
+	if (!(pcr & cpu_to_be32(PCR_ONLINE))) {
+		cmp_error(c, "plug is not on-line\n");
+		return -ECONNREFUSED;
+	}
+
+	return 0;
+}
+
+/**
+ * cmp_connection_establish - establish a connection to the target
+ * @c: the connection manager
+ *
+ * This function establishes a point-to-point connection from the local
+ * computer to the target by allocating isochronous resources (channel and
+ * bandwidth) and setting the target's input/output plug control register.
+ * When this function succeeds, the caller is responsible for starting
+ * transmitting packets.
+ */
+int cmp_connection_establish(struct cmp_connection *c)
+{
+	int err;
+
+	guard(mutex)(&c->mutex);
+
+	if (WARN_ON(c->connected))
+		return -EISCONN;
+
+retry_after_bus_reset:
+	if (c->direction == CMP_OUTPUT)
+		err = pcr_modify(c, opcr_set_modify, pcr_set_check,
+				 ABORT_ON_BUS_RESET);
+	else
+		err = pcr_modify(c, ipcr_set_modify, pcr_set_check,
+				 ABORT_ON_BUS_RESET);
+
+	if (err == -EAGAIN) {
+		err = fw_iso_resources_update(&c->resources);
+		if (err >= 0)
+			goto retry_after_bus_reset;
+	}
+	if (err >= 0)
+		c->connected = true;
+
+	return err;
+}
+EXPORT_SYMBOL(cmp_connection_establish);
+
+static __be32 pcr_break_modify(struct cmp_connection *c, __be32 pcr)
+{
+	return pcr & ~cpu_to_be32(PCR_BCAST_CONN | PCR_P2P_CONN_MASK);
+}
+
+/**
+ * cmp_connection_break - break the connection to the target
+ * @c: the connection manager
+ *
+ * This function deactives the connection in the target's input/output plug
+ * control register, and frees the isochronous resources of the connection.
+ * Before calling this function, the caller should cease transmitting packets.
+ */
+void cmp_connection_break(struct cmp_connection *c)
+{
+	int err;
+
+	guard(mutex)(&c->mutex);
+
+	if (!c->connected)
+		return;
+
+	err = pcr_modify(c, pcr_break_modify, NULL, SUCCEED_ON_BUS_RESET);
+	if (err < 0)
+		cmp_error(c, "plug is still connected\n");
+
+	c->connected = false;
+}
+EXPORT_SYMBOL(cmp_connection_break);