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/iio/chemical/bme680.h b/drivers/iio/chemical/bme680.h
new file mode 100644
index 000000000..7d86ed8b0
--- /dev/null
+++ b/drivers/iio/chemical/bme680.h
@@ -0,0 +1,89 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef BME680_H_
+#define BME680_H_
+
+#include <linux/pm.h>
+#include <linux/regmap.h>
+
+#define BME680_REG_CHIP_ID			0xD0
+#define   BME680_CHIP_ID_VAL			0x61
+#define BME680_REG_SOFT_RESET			0xE0
+#define   BME680_CMD_SOFTRESET			0xB6
+#define BME680_REG_STATUS			0x73
+#define   BME680_SPI_MEM_PAGE_BIT		BIT(4)
+#define     BME680_SPI_MEM_PAGE_1_VAL		1
+
+#define BME680_REG_TEMP_MSB			0x22
+#define BME680_REG_PRESS_MSB			0x1F
+#define BME680_REG_HUMIDITY_MSB			0x25
+#define BME680_REG_GAS_MSB			0x2A
+#define BME680_REG_GAS_R_LSB			0x2B
+#define   BME680_GAS_STAB_BIT			BIT(4)
+#define   BME680_GAS_RANGE_MASK			GENMASK(3, 0)
+
+#define BME680_REG_CTRL_HUMIDITY		0x72
+#define   BME680_OSRS_HUMIDITY_MASK		GENMASK(2, 0)
+
+#define BME680_REG_CTRL_MEAS			0x74
+#define   BME680_OSRS_TEMP_MASK			GENMASK(7, 5)
+#define   BME680_OSRS_PRESS_MASK		GENMASK(4, 2)
+#define   BME680_MODE_MASK			GENMASK(1, 0)
+
+#define BME680_REG_CONFIG			0x75
+#define   BME680_FILTER_MASK			GENMASK(4, 2)
+#define     BME680_FILTER_COEFF_VAL		BIT(1)
+
+/* TEMP/PRESS/HUMID reading skipped */
+#define BME680_MEAS_SKIPPED			0x8000
+
+#define BME680_MAX_OVERFLOW_VAL			0x40000000
+#define BME680_HUM_REG_SHIFT_VAL		4
+#define BME680_BIT_H1_DATA_MASK			GENMASK(3, 0)
+
+#define   BME680_RHRANGE_MASK			GENMASK(5, 4)
+#define BME680_REG_RES_HEAT_VAL			0x00
+#define   BME680_RSERROR_MASK			GENMASK(7, 4)
+#define BME680_REG_IDAC_HEAT_0			0x50
+#define BME680_REG_RES_HEAT_0			0x5A
+#define BME680_REG_GAS_WAIT_0			0x64
+#define BME680_ADC_GAS_RES			GENMASK(15, 6)
+#define BME680_AMB_TEMP				25
+
+#define BME680_REG_CTRL_GAS_1			0x71
+#define   BME680_RUN_GAS_MASK			BIT(4)
+#define   BME680_NB_CONV_MASK			GENMASK(3, 0)
+
+#define BME680_REG_MEAS_STAT_0			0x1D
+#define   BME680_NEW_DATA_BIT			BIT(7)
+#define   BME680_GAS_MEAS_BIT			BIT(6)
+#define   BME680_MEAS_BIT			BIT(5)
+
+#define BME680_TEMP_NUM_BYTES			3
+#define BME680_PRESS_NUM_BYTES			3
+#define BME680_HUMID_NUM_BYTES			2
+#define BME680_GAS_NUM_BYTES			2
+
+#define BME680_MEAS_TRIM_MASK			GENMASK(24, 4)
+
+/* Datasheet Section 1.1, Table 1 */
+#define BME680_STARTUP_TIME_US			2000
+
+#define BME680_NUM_CHANNELS			4
+#define BME680_NUM_BULK_READ_REGS		15
+
+/* Calibration Parameters */
+#define BME680_T2_LSB_REG	0x8A
+#define BME680_H2_MSB_REG	0xE1
+#define BME680_GH3_REG		0xEE
+
+#define BME680_CALIB_RANGE_1_LEN               23
+#define BME680_CALIB_RANGE_2_LEN               14
+#define BME680_CALIB_RANGE_3_LEN               5
+
+extern const struct regmap_config bme680_regmap_config;
+extern const struct dev_pm_ops bme680_dev_pm_ops;
+
+int bme680_core_probe(struct device *dev, struct regmap *regmap,
+		      const char *name);
+
+#endif  /* BME680_H_ */