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, 89 insertions, 0 deletions

diff --git a/drivers/media/dvb-frontends/bsbe1.h b/drivers/media/dvb-frontends/bsbe1.h
new file mode 100644
index 000000000..b4b81e1dd
--- /dev/null
+++ b/drivers/media/dvb-frontends/bsbe1.h
@@ -0,0 +1,89 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * bsbe1.h - ALPS BSBE1 tuner support
+ *
+ * the project's page is at https://linuxtv.org
+ */
+
+#ifndef BSBE1_H
+#define BSBE1_H
+
+static u8 alps_bsbe1_inittab[] = {
+	0x01, 0x15,   /* XTAL = 4MHz, VCO = 352 MHz */
+	0x02, 0x30,   /* MCLK = 88 MHz */
+	0x03, 0x00,   /* ACR output 0 */
+	0x04, 0x7d,   /* F22FR = 0x7d, F22 = f_VCO / 128 / 0x7d = 22 kHz */
+	0x05, 0x05,   /* I2CT = 0, SCLT = 1, SDAT = 1 */
+	0x06, 0x00,   /* DAC output 0 */
+	0x08, 0x40,   /* DiSEqC off, LNB power on OP2/LOCK pin on */
+	0x09, 0x00,   /* FIFO */
+	0x0c, 0x51,   /* OP1/OP0 normal, val = 1 (LNB power on) */
+	0x0d, 0x82,   /* DC offset compensation = on, beta_agc1 = 2 */
+	0x0f, 0x92,   /* AGC1R */
+	0x10, 0x34,   /* AGC2O */
+	0x11, 0x84,   /* TLSR */
+	0x12, 0xb9,   /* CFD */
+	0x15, 0xc9,   /* lock detector threshold */
+	0x28, 0x00,   /* out imp: normal, type: parallel, FEC mode: QPSK */
+	0x33, 0xfc,   /* RS control */
+	0x34, 0x93,   /* count viterbi bit errors per 2E18 bytes */
+	0xff, 0xff
+};
+
+
+static int alps_bsbe1_set_symbol_rate(struct dvb_frontend* fe, u32 srate, u32 ratio)
+{
+	u8 aclk = 0;
+	u8 bclk = 0;
+
+	if (srate < 1500000) { aclk = 0xb7; bclk = 0x47; }
+	else if (srate < 3000000) { aclk = 0xb7; bclk = 0x4b; }
+	else if (srate < 7000000) { aclk = 0xb7; bclk = 0x4f; }
+	else if (srate < 14000000) { aclk = 0xb7; bclk = 0x53; }
+	else if (srate < 30000000) { aclk = 0xb6; bclk = 0x53; }
+	else if (srate < 45000000) { aclk = 0xb4; bclk = 0x51; }
+
+	stv0299_writereg(fe, 0x13, aclk);
+	stv0299_writereg(fe, 0x14, bclk);
+	stv0299_writereg(fe, 0x1f, (ratio >> 16) & 0xff);
+	stv0299_writereg(fe, 0x20, (ratio >>  8) & 0xff);
+	stv0299_writereg(fe, 0x21, (ratio      ) & 0xf0);
+
+	return 0;
+}
+
+static int alps_bsbe1_tuner_set_params(struct dvb_frontend *fe)
+{
+	struct dtv_frontend_properties *p = &fe->dtv_property_cache;
+	int ret;
+	u8 data[4];
+	u32 div;
+	struct i2c_msg msg = { .addr = 0x61, .flags = 0, .buf = data, .len = sizeof(data) };
+	struct i2c_adapter *i2c = fe->tuner_priv;
+
+	if ((p->frequency < 950000) || (p->frequency > 2150000))
+		return -EINVAL;
+
+	div = p->frequency / 1000;
+	data[0] = (div >> 8) & 0x7f;
+	data[1] = div & 0xff;
+	data[2] = 0x80 | ((div & 0x18000) >> 10) | 0x1;
+	data[3] = 0xe0;
+
+	if (fe->ops.i2c_gate_ctrl)
+		fe->ops.i2c_gate_ctrl(fe, 1);
+	ret = i2c_transfer(i2c, &msg, 1);
+	return (ret != 1) ? -EIO : 0;
+}
+
+static struct stv0299_config alps_bsbe1_config = {
+	.demod_address = 0x68,
+	.inittab = alps_bsbe1_inittab,
+	.mclk = 88000000UL,
+	.invert = 1,
+	.skip_reinit = 0,
+	.min_delay_ms = 100,
+	.set_symbol_rate = alps_bsbe1_set_symbol_rate,
+};
+
+#endif