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-88pm886.c | 96 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 96 insertions(+) create mode 100644 drivers/rtc/rtc-88pm886.c (limited to 'drivers/rtc/rtc-88pm886.c') diff --git a/drivers/rtc/rtc-88pm886.c b/drivers/rtc/rtc-88pm886.c new file mode 100644 index 000000000..71443ae1b --- /dev/null +++ b/drivers/rtc/rtc-88pm886.c @@ -0,0 +1,96 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include +#include +#include + +#include + +/* + * Time is calculated as the sum of a 32-bit read-only advancing counter and a + * writeable constant offset stored in the chip's spare registers. + */ + +static int pm886_rtc_read_time(struct device *dev, struct rtc_time *tm) +{ + struct regmap *regmap = dev_get_drvdata(dev); + u32 time; + u32 buf; + int ret; + + ret = regmap_bulk_read(regmap, PM886_REG_RTC_SPARE1, &buf, 4); + if (ret) + return ret; + time = buf; + + ret = regmap_bulk_read(regmap, PM886_REG_RTC_CNT1, &buf, 4); + if (ret) + return ret; + time += buf; + + rtc_time64_to_tm(time, tm); + + return 0; +} + +static int pm886_rtc_set_time(struct device *dev, struct rtc_time *tm) +{ + struct regmap *regmap = dev_get_drvdata(dev); + u32 buf; + int ret; + + ret = regmap_bulk_read(regmap, PM886_REG_RTC_CNT1, &buf, 4); + if (ret) + return ret; + + buf = rtc_tm_to_time64(tm) - buf; + + return regmap_bulk_write(regmap, PM886_REG_RTC_SPARE1, &buf, 4); +} + +static const struct rtc_class_ops pm886_rtc_ops = { + .read_time = pm886_rtc_read_time, + .set_time = pm886_rtc_set_time, +}; + +static int pm886_rtc_probe(struct platform_device *pdev) +{ + struct pm886_chip *chip = dev_get_drvdata(pdev->dev.parent); + struct device *dev = &pdev->dev; + struct rtc_device *rtc; + int ret; + + platform_set_drvdata(pdev, chip->regmap); + + rtc = devm_rtc_allocate_device(dev); + if (IS_ERR(rtc)) + return dev_err_probe(dev, PTR_ERR(rtc), + "Failed to allocate RTC device\n"); + + rtc->ops = &pm886_rtc_ops; + rtc->range_max = U32_MAX; + + ret = devm_rtc_register_device(rtc); + if (ret) + return dev_err_probe(dev, ret, "Failed to register RTC device\n"); + + return 0; +} + +static const struct platform_device_id pm886_rtc_id_table[] = { + { .name = "88pm886-rtc" }, + { } +}; +MODULE_DEVICE_TABLE(platform, pm886_rtc_id_table); + +static struct platform_driver pm886_rtc_driver = { + .driver = { + .name = "88pm886-rtc", + }, + .probe = pm886_rtc_probe, + .id_table = pm886_rtc_id_table, +}; +module_platform_driver(pm886_rtc_driver); + +MODULE_DESCRIPTION("Marvell 88PM886 RTC driver"); +MODULE_AUTHOR("Karel Balej "); +MODULE_LICENSE("GPL"); -- cgit v1.3.1