From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops 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 --- drivers/rtc/rtc-ds1672.c | 160 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 160 insertions(+) create mode 100644 drivers/rtc/rtc-ds1672.c (limited to 'drivers/rtc/rtc-ds1672.c') diff --git a/drivers/rtc/rtc-ds1672.c b/drivers/rtc/rtc-ds1672.c new file mode 100644 index 000000000..c610beb55 --- /dev/null +++ b/drivers/rtc/rtc-ds1672.c @@ -0,0 +1,160 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * An rtc/i2c driver for the Dallas DS1672 + * Copyright 2005-06 Tower Technologies + * + * Author: Alessandro Zummo + */ + +#include +#include +#include + +/* Registers */ + +#define DS1672_REG_CNT_BASE 0 +#define DS1672_REG_CONTROL 4 +#define DS1672_REG_TRICKLE 5 + +#define DS1672_REG_CONTROL_EOSC 0x80 + +/* + * In the routines that deal directly with the ds1672 hardware, we use + * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch + * Time is set to UTC. + */ +static int ds1672_read_time(struct device *dev, struct rtc_time *tm) +{ + struct i2c_client *client = to_i2c_client(dev); + unsigned long time; + unsigned char addr = DS1672_REG_CONTROL; + unsigned char buf[4]; + + struct i2c_msg msgs[] = { + {/* setup read ptr */ + .addr = client->addr, + .len = 1, + .buf = &addr + }, + {/* read date */ + .addr = client->addr, + .flags = I2C_M_RD, + .len = 1, + .buf = buf + }, + }; + + /* read control register */ + if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) { + dev_warn(&client->dev, "Unable to read the control register\n"); + return -EIO; + } + + if (buf[0] & DS1672_REG_CONTROL_EOSC) { + dev_warn(&client->dev, "Oscillator not enabled. Set time to enable.\n"); + return -EINVAL; + } + + addr = DS1672_REG_CNT_BASE; + msgs[1].len = 4; + + /* read date registers */ + if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) { + dev_err(&client->dev, "%s: read error\n", __func__); + return -EIO; + } + + dev_dbg(&client->dev, + "%s: raw read data - counters=%02x,%02x,%02x,%02x\n", + __func__, buf[0], buf[1], buf[2], buf[3]); + + time = ((unsigned long)buf[3] << 24) | (buf[2] << 16) | + (buf[1] << 8) | buf[0]; + + rtc_time64_to_tm(time, tm); + + dev_dbg(&client->dev, "%s: tm is %ptR\n", __func__, tm); + + return 0; +} + +static int ds1672_set_time(struct device *dev, struct rtc_time *tm) +{ + struct i2c_client *client = to_i2c_client(dev); + int xfer; + unsigned char buf[6]; + unsigned long secs = rtc_tm_to_time64(tm); + + buf[0] = DS1672_REG_CNT_BASE; + buf[1] = secs & 0x000000FF; + buf[2] = (secs & 0x0000FF00) >> 8; + buf[3] = (secs & 0x00FF0000) >> 16; + buf[4] = (secs & 0xFF000000) >> 24; + buf[5] = 0; /* set control reg to enable counting */ + + xfer = i2c_master_send(client, buf, 6); + if (xfer != 6) { + dev_err(&client->dev, "%s: send: %d\n", __func__, xfer); + return -EIO; + } + + return 0; +} + +static const struct rtc_class_ops ds1672_rtc_ops = { + .read_time = ds1672_read_time, + .set_time = ds1672_set_time, +}; + +static int ds1672_probe(struct i2c_client *client) +{ + int err = 0; + struct rtc_device *rtc; + + dev_dbg(&client->dev, "%s\n", __func__); + + if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) + return -ENODEV; + + rtc = devm_rtc_allocate_device(&client->dev); + if (IS_ERR(rtc)) + return PTR_ERR(rtc); + + rtc->ops = &ds1672_rtc_ops; + rtc->range_max = U32_MAX; + + err = devm_rtc_register_device(rtc); + if (err) + return err; + + i2c_set_clientdata(client, rtc); + + return 0; +} + +static const struct i2c_device_id ds1672_id[] = { + { .name = "ds1672" }, + { } +}; +MODULE_DEVICE_TABLE(i2c, ds1672_id); + +static const __maybe_unused struct of_device_id ds1672_of_match[] = { + { .compatible = "dallas,ds1672" }, + { } +}; +MODULE_DEVICE_TABLE(of, ds1672_of_match); + +static struct i2c_driver ds1672_driver = { + .driver = { + .name = "rtc-ds1672", + .of_match_table = of_match_ptr(ds1672_of_match), + }, + .probe = ds1672_probe, + .id_table = ds1672_id, +}; + +module_i2c_driver(ds1672_driver); + +MODULE_AUTHOR("Alessandro Zummo "); +MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1