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-r9701.c | 145 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 145 insertions(+) create mode 100644 drivers/rtc/rtc-r9701.c (limited to 'drivers/rtc/rtc-r9701.c') diff --git a/drivers/rtc/rtc-r9701.c b/drivers/rtc/rtc-r9701.c new file mode 100644 index 000000000..60a3c3d74 --- /dev/null +++ b/drivers/rtc/rtc-r9701.c @@ -0,0 +1,145 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Driver for Epson RTC-9701JE + * + * Copyright (C) 2008 Magnus Damm + * + * Based on rtc-max6902.c + * + * Copyright (C) 2006 8D Technologies inc. + * Copyright (C) 2004 Compulab Ltd. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define RSECCNT 0x00 /* Second Counter */ +#define RMINCNT 0x01 /* Minute Counter */ +#define RHRCNT 0x02 /* Hour Counter */ +#define RWKCNT 0x03 /* Week Counter */ +#define RDAYCNT 0x04 /* Day Counter */ +#define RMONCNT 0x05 /* Month Counter */ +#define RYRCNT 0x06 /* Year Counter */ +#define R100CNT 0x07 /* Y100 Counter */ +#define RMINAR 0x08 /* Minute Alarm */ +#define RHRAR 0x09 /* Hour Alarm */ +#define RWKAR 0x0a /* Week/Day Alarm */ +#define RTIMCNT 0x0c /* Interval Timer */ +#define REXT 0x0d /* Extension Register */ +#define RFLAG 0x0e /* RTC Flag Register */ +#define RCR 0x0f /* RTC Control Register */ + +static int write_reg(struct device *dev, int address, unsigned char data) +{ + struct spi_device *spi = to_spi_device(dev); + unsigned char buf[2]; + + buf[0] = address & 0x7f; + buf[1] = data; + + return spi_write(spi, buf, ARRAY_SIZE(buf)); +} + +static int read_regs(struct device *dev, unsigned char *regs, int no_regs) +{ + struct spi_device *spi = to_spi_device(dev); + u8 txbuf[1], rxbuf[1]; + int k, ret; + + ret = 0; + + for (k = 0; ret == 0 && k < no_regs; k++) { + txbuf[0] = 0x80 | regs[k]; + ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1); + regs[k] = rxbuf[0]; + } + + return ret; +} + +static int r9701_get_datetime(struct device *dev, struct rtc_time *dt) +{ + int ret; + unsigned char buf[] = { RSECCNT, RMINCNT, RHRCNT, + RDAYCNT, RMONCNT, RYRCNT }; + + ret = read_regs(dev, buf, ARRAY_SIZE(buf)); + if (ret) + return ret; + + dt->tm_sec = bcd2bin(buf[0]); /* RSECCNT */ + dt->tm_min = bcd2bin(buf[1]); /* RMINCNT */ + dt->tm_hour = bcd2bin(buf[2]); /* RHRCNT */ + + dt->tm_mday = bcd2bin(buf[3]); /* RDAYCNT */ + dt->tm_mon = bcd2bin(buf[4]) - 1; /* RMONCNT */ + dt->tm_year = bcd2bin(buf[5]) + 100; /* RYRCNT */ + + return 0; +} + +static int r9701_set_datetime(struct device *dev, struct rtc_time *dt) +{ + int ret; + + ret = write_reg(dev, RHRCNT, bin2bcd(dt->tm_hour)); + ret = ret ? ret : write_reg(dev, RMINCNT, bin2bcd(dt->tm_min)); + ret = ret ? ret : write_reg(dev, RSECCNT, bin2bcd(dt->tm_sec)); + ret = ret ? ret : write_reg(dev, RDAYCNT, bin2bcd(dt->tm_mday)); + ret = ret ? ret : write_reg(dev, RMONCNT, bin2bcd(dt->tm_mon + 1)); + ret = ret ? ret : write_reg(dev, RYRCNT, bin2bcd(dt->tm_year - 100)); + + return ret; +} + +static const struct rtc_class_ops r9701_rtc_ops = { + .read_time = r9701_get_datetime, + .set_time = r9701_set_datetime, +}; + +static int r9701_probe(struct spi_device *spi) +{ + struct rtc_device *rtc; + unsigned char tmp; + int res; + + tmp = R100CNT; + res = read_regs(&spi->dev, &tmp, 1); + if (res || tmp != 0x20) { + dev_err(&spi->dev, "cannot read RTC register\n"); + return -ENODEV; + } + + rtc = devm_rtc_allocate_device(&spi->dev); + if (IS_ERR(rtc)) + return PTR_ERR(rtc); + + spi_set_drvdata(spi, rtc); + rtc->ops = &r9701_rtc_ops; + rtc->range_min = RTC_TIMESTAMP_BEGIN_2000; + rtc->range_max = RTC_TIMESTAMP_END_2099; + + return devm_rtc_register_device(rtc); +} + +static struct spi_driver r9701_driver = { + .driver = { + .name = "rtc-r9701", + }, + .probe = r9701_probe, +}; + +module_spi_driver(r9701_driver); + +MODULE_DESCRIPTION("r9701 spi RTC driver"); +MODULE_AUTHOR("Magnus Damm "); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("spi:rtc-r9701"); -- cgit v1.3.1