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, 250 insertions, 0 deletions

diff --git a/drivers/media/firewire/firedtv-fe.c b/drivers/media/firewire/firedtv-fe.c
new file mode 100644
index 000000000..a73c1aefd
--- /dev/null
+++ b/drivers/media/firewire/firedtv-fe.c
@@ -0,0 +1,250 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * FireDTV driver (formerly known as FireSAT)
+ *
+ * Copyright (C) 2004 Andreas Monitzer <andy@monitzer.com>
+ * Copyright (C) 2008 Henrik Kurelid <henrik@kurelid.se>
+ */
+
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/types.h>
+
+#include <media/dvb_frontend.h>
+
+#include "firedtv.h"
+
+static int fdtv_dvb_init(struct dvb_frontend *fe)
+{
+	struct firedtv *fdtv = fe->sec_priv;
+	int err;
+
+	/* FIXME - allocate free channel at IRM */
+	fdtv->isochannel = fdtv->adapter.num;
+
+	err = cmp_establish_pp_connection(fdtv, fdtv->subunit,
+					  fdtv->isochannel);
+	if (err) {
+		dev_err(fdtv->device,
+			"could not establish point to point connection\n");
+		return err;
+	}
+
+	return fdtv_start_iso(fdtv);
+}
+
+static int fdtv_sleep(struct dvb_frontend *fe)
+{
+	struct firedtv *fdtv = fe->sec_priv;
+
+	fdtv_stop_iso(fdtv);
+	cmp_break_pp_connection(fdtv, fdtv->subunit, fdtv->isochannel);
+	fdtv->isochannel = -1;
+	return 0;
+}
+
+#define LNBCONTROL_DONTCARE 0xff
+
+static int fdtv_diseqc_send_master_cmd(struct dvb_frontend *fe,
+				       struct dvb_diseqc_master_cmd *cmd)
+{
+	struct firedtv *fdtv = fe->sec_priv;
+
+	return avc_lnb_control(fdtv, LNBCONTROL_DONTCARE, LNBCONTROL_DONTCARE,
+			       LNBCONTROL_DONTCARE, 1, cmd);
+}
+
+static int fdtv_diseqc_send_burst(struct dvb_frontend *fe,
+				  enum fe_sec_mini_cmd minicmd)
+{
+	return 0;
+}
+
+static int fdtv_set_tone(struct dvb_frontend *fe, enum fe_sec_tone_mode tone)
+{
+	struct firedtv *fdtv = fe->sec_priv;
+
+	fdtv->tone = tone;
+	return 0;
+}
+
+static int fdtv_set_voltage(struct dvb_frontend *fe,
+			    enum fe_sec_voltage voltage)
+{
+	struct firedtv *fdtv = fe->sec_priv;
+
+	fdtv->voltage = voltage;
+	return 0;
+}
+
+static int fdtv_read_status(struct dvb_frontend *fe, enum fe_status *status)
+{
+	struct firedtv *fdtv = fe->sec_priv;
+	struct firedtv_tuner_status stat;
+
+	if (avc_tuner_status(fdtv, &stat))
+		return -EINVAL;
+
+	if (stat.no_rf)
+		*status = 0;
+	else
+		*status = FE_HAS_SIGNAL | FE_HAS_VITERBI | FE_HAS_SYNC |
+			  FE_HAS_CARRIER | FE_HAS_LOCK;
+	return 0;
+}
+
+static int fdtv_read_ber(struct dvb_frontend *fe, u32 *ber)
+{
+	struct firedtv *fdtv = fe->sec_priv;
+	struct firedtv_tuner_status stat;
+
+	if (avc_tuner_status(fdtv, &stat))
+		return -EINVAL;
+
+	*ber = stat.ber;
+	return 0;
+}
+
+static int fdtv_read_signal_strength(struct dvb_frontend *fe, u16 *strength)
+{
+	struct firedtv *fdtv = fe->sec_priv;
+	struct firedtv_tuner_status stat;
+
+	if (avc_tuner_status(fdtv, &stat))
+		return -EINVAL;
+
+	*strength = stat.signal_strength << 8;
+	return 0;
+}
+
+static int fdtv_read_snr(struct dvb_frontend *fe, u16 *snr)
+{
+	struct firedtv *fdtv = fe->sec_priv;
+	struct firedtv_tuner_status stat;
+
+	if (avc_tuner_status(fdtv, &stat))
+		return -EINVAL;
+
+	/* C/N[dB] = -10 * log10(snr / 65535) */
+	*snr = stat.carrier_noise_ratio * 257;
+	return 0;
+}
+
+static int fdtv_read_uncorrected_blocks(struct dvb_frontend *fe, u32 *ucblocks)
+{
+	return -EOPNOTSUPP;
+}
+
+static int fdtv_set_frontend(struct dvb_frontend *fe)
+{
+	struct dtv_frontend_properties *p = &fe->dtv_property_cache;
+	struct firedtv *fdtv = fe->sec_priv;
+
+	return avc_tuner_dsd(fdtv, p);
+}
+
+void fdtv_frontend_init(struct firedtv *fdtv, const char *name)
+{
+	struct dvb_frontend_ops *ops = &fdtv->fe.ops;
+	struct dvb_frontend_internal_info *fi = &ops->info;
+
+	ops->init			= fdtv_dvb_init;
+	ops->sleep			= fdtv_sleep;
+
+	ops->set_frontend		= fdtv_set_frontend;
+
+	ops->read_status		= fdtv_read_status;
+	ops->read_ber			= fdtv_read_ber;
+	ops->read_signal_strength	= fdtv_read_signal_strength;
+	ops->read_snr			= fdtv_read_snr;
+	ops->read_ucblocks		= fdtv_read_uncorrected_blocks;
+
+	ops->diseqc_send_master_cmd	= fdtv_diseqc_send_master_cmd;
+	ops->diseqc_send_burst		= fdtv_diseqc_send_burst;
+	ops->set_tone			= fdtv_set_tone;
+	ops->set_voltage		= fdtv_set_voltage;
+
+	switch (fdtv->type) {
+	case FIREDTV_DVB_S:
+		ops->delsys[0]		= SYS_DVBS;
+
+		fi->frequency_min_hz	=   950 * MHz;
+		fi->frequency_max_hz	=  2150 * MHz;
+		fi->frequency_stepsize_hz = 125 * kHz;
+		fi->symbol_rate_min	= 1000000;
+		fi->symbol_rate_max	= 40000000;
+
+		fi->caps		= FE_CAN_INVERSION_AUTO |
+					  FE_CAN_FEC_1_2	|
+					  FE_CAN_FEC_2_3	|
+					  FE_CAN_FEC_3_4	|
+					  FE_CAN_FEC_5_6	|
+					  FE_CAN_FEC_7_8	|
+					  FE_CAN_FEC_AUTO	|
+					  FE_CAN_QPSK;
+		break;
+
+	case FIREDTV_DVB_S2:
+		ops->delsys[0]		= SYS_DVBS;
+		ops->delsys[1]		= SYS_DVBS2;
+
+		fi->frequency_min_hz	=   950 * MHz;
+		fi->frequency_max_hz	=  2150 * MHz;
+		fi->frequency_stepsize_hz = 125 * kHz;
+		fi->symbol_rate_min	= 1000000;
+		fi->symbol_rate_max	= 40000000;
+
+		fi->caps		= FE_CAN_INVERSION_AUTO |
+					  FE_CAN_FEC_1_2        |
+					  FE_CAN_FEC_2_3        |
+					  FE_CAN_FEC_3_4        |
+					  FE_CAN_FEC_5_6        |
+					  FE_CAN_FEC_7_8        |
+					  FE_CAN_FEC_AUTO       |
+					  FE_CAN_QPSK           |
+					  FE_CAN_2G_MODULATION;
+		break;
+
+	case FIREDTV_DVB_C:
+		ops->delsys[0]		= SYS_DVBC_ANNEX_A;
+
+		fi->frequency_min_hz	=      47 * MHz;
+		fi->frequency_max_hz	=     866 * MHz;
+		fi->frequency_stepsize_hz = 62500;
+		fi->symbol_rate_min	= 870000;
+		fi->symbol_rate_max	= 6900000;
+
+		fi->caps		= FE_CAN_INVERSION_AUTO |
+					  FE_CAN_QAM_16		|
+					  FE_CAN_QAM_32		|
+					  FE_CAN_QAM_64		|
+					  FE_CAN_QAM_128	|
+					  FE_CAN_QAM_256	|
+					  FE_CAN_QAM_AUTO;
+		break;
+
+	case FIREDTV_DVB_T:
+		ops->delsys[0]		= SYS_DVBT;
+
+		fi->frequency_min_hz	=  49 * MHz;
+		fi->frequency_max_hz	= 861 * MHz;
+		fi->frequency_stepsize_hz = 62500;
+
+		fi->caps		= FE_CAN_INVERSION_AUTO		|
+					  FE_CAN_FEC_2_3		|
+					  FE_CAN_TRANSMISSION_MODE_AUTO |
+					  FE_CAN_GUARD_INTERVAL_AUTO	|
+					  FE_CAN_HIERARCHY_AUTO;
+		break;
+
+	default:
+		dev_err(fdtv->device, "no frontend for model type %d\n",
+			fdtv->type);
+	}
+	strscpy(fi->name, name, sizeof(fi->name));
+
+	fdtv->fe.dvb = &fdtv->adapter;
+	fdtv->fe.sec_priv = fdtv;
+}