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/char/ds1620.c | 424 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 424 insertions(+) create mode 100644 drivers/char/ds1620.c (limited to 'drivers/char/ds1620.c') diff --git a/drivers/char/ds1620.c b/drivers/char/ds1620.c new file mode 100644 index 000000000..44a1cdbd4 --- /dev/null +++ b/drivers/char/ds1620.c @@ -0,0 +1,424 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * linux/drivers/char/ds1620.c: Dallas Semiconductors DS1620 + * thermometer driver (as used in the Rebel.com NetWinder) + */ +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include + +#ifdef CONFIG_PROC_FS +/* define for /proc interface */ +#define THERM_USE_PROC +#endif + +/* Definitions for DS1620 chip */ +#define THERM_START_CONVERT 0xee +#define THERM_RESET 0xaf +#define THERM_READ_CONFIG 0xac +#define THERM_READ_TEMP 0xaa +#define THERM_READ_TL 0xa2 +#define THERM_READ_TH 0xa1 +#define THERM_WRITE_CONFIG 0x0c +#define THERM_WRITE_TL 0x02 +#define THERM_WRITE_TH 0x01 + +#define CFG_CPU 2 +#define CFG_1SHOT 1 + +static DEFINE_MUTEX(ds1620_mutex); +static const char *fan_state[] = { "off", "on", "on (hardwired)" }; + +/* + * Start of NetWinder specifics + * Note! We have to hold the gpio lock with IRQs disabled over the + * whole of our transaction to the Dallas chip, since there is a + * chance that the WaveArtist driver could touch these bits to + * enable or disable the speaker. + */ +extern unsigned int system_rev; + +static inline void netwinder_ds1620_set_clk(int clk) +{ + nw_gpio_modify_op(GPIO_DSCLK, clk ? GPIO_DSCLK : 0); +} + +static inline void netwinder_ds1620_set_data(int dat) +{ + nw_gpio_modify_op(GPIO_DATA, dat ? GPIO_DATA : 0); +} + +static inline int netwinder_ds1620_get_data(void) +{ + return nw_gpio_read() & GPIO_DATA; +} + +static inline void netwinder_ds1620_set_data_dir(int dir) +{ + nw_gpio_modify_io(GPIO_DATA, dir ? GPIO_DATA : 0); +} + +static inline void netwinder_ds1620_reset(void) +{ + nw_cpld_modify(CPLD_DS_ENABLE, 0); + nw_cpld_modify(CPLD_DS_ENABLE, CPLD_DS_ENABLE); +} + +static inline void netwinder_lock(unsigned long *flags) +{ + raw_spin_lock_irqsave(&nw_gpio_lock, *flags); +} + +static inline void netwinder_unlock(unsigned long *flags) +{ + raw_spin_unlock_irqrestore(&nw_gpio_lock, *flags); +} + +static inline void netwinder_set_fan(int i) +{ + unsigned long flags; + + raw_spin_lock_irqsave(&nw_gpio_lock, flags); + nw_gpio_modify_op(GPIO_FAN, i ? GPIO_FAN : 0); + raw_spin_unlock_irqrestore(&nw_gpio_lock, flags); +} + +static inline int netwinder_get_fan(void) +{ + if ((system_rev & 0xf000) == 0x4000) + return FAN_ALWAYS_ON; + + return (nw_gpio_read() & GPIO_FAN) ? FAN_ON : FAN_OFF; +} + +/* + * End of NetWinder specifics + */ + +static void ds1620_send_bits(int nr, int value) +{ + int i; + + for (i = 0; i < nr; i++) { + netwinder_ds1620_set_data(value & 1); + netwinder_ds1620_set_clk(0); + udelay(1); + netwinder_ds1620_set_clk(1); + udelay(1); + + value >>= 1; + } +} + +static unsigned int ds1620_recv_bits(int nr) +{ + unsigned int value = 0, mask = 1; + int i; + + netwinder_ds1620_set_data(0); + + for (i = 0; i < nr; i++) { + netwinder_ds1620_set_clk(0); + udelay(1); + + if (netwinder_ds1620_get_data()) + value |= mask; + + mask <<= 1; + + netwinder_ds1620_set_clk(1); + udelay(1); + } + + return value; +} + +static void ds1620_out(int cmd, int bits, int value) +{ + unsigned long flags; + + netwinder_lock(&flags); + netwinder_ds1620_set_clk(1); + netwinder_ds1620_set_data_dir(0); + netwinder_ds1620_reset(); + + udelay(1); + + ds1620_send_bits(8, cmd); + if (bits) + ds1620_send_bits(bits, value); + + udelay(1); + + netwinder_ds1620_reset(); + netwinder_unlock(&flags); + + msleep(20); +} + +static unsigned int ds1620_in(int cmd, int bits) +{ + unsigned long flags; + unsigned int value; + + netwinder_lock(&flags); + netwinder_ds1620_set_clk(1); + netwinder_ds1620_set_data_dir(0); + netwinder_ds1620_reset(); + + udelay(1); + + ds1620_send_bits(8, cmd); + + netwinder_ds1620_set_data_dir(1); + value = ds1620_recv_bits(bits); + + netwinder_ds1620_reset(); + netwinder_unlock(&flags); + + return value; +} + +static int cvt_9_to_int(unsigned int val) +{ + if (val & 0x100) + val |= 0xfffffe00; + + return val; +} + +static void ds1620_write_state(struct therm *therm) +{ + ds1620_out(THERM_WRITE_CONFIG, 8, CFG_CPU); + ds1620_out(THERM_WRITE_TL, 9, therm->lo); + ds1620_out(THERM_WRITE_TH, 9, therm->hi); + ds1620_out(THERM_START_CONVERT, 0, 0); +} + +static void ds1620_read_state(struct therm *therm) +{ + therm->lo = cvt_9_to_int(ds1620_in(THERM_READ_TL, 9)); + therm->hi = cvt_9_to_int(ds1620_in(THERM_READ_TH, 9)); +} + +static int ds1620_open(struct inode *inode, struct file *file) +{ + return stream_open(inode, file); +} + +static ssize_t +ds1620_read(struct file *file, char __user *buf, size_t count, loff_t *ptr) +{ + signed int cur_temp; + signed char cur_temp_degF; + + cur_temp = cvt_9_to_int(ds1620_in(THERM_READ_TEMP, 9)) >> 1; + + /* convert to Fahrenheit, as per wdt.c */ + cur_temp_degF = (cur_temp * 9) / 5 + 32; + + if (copy_to_user(buf, &cur_temp_degF, 1)) + return -EFAULT; + + return 1; +} + +static int +ds1620_ioctl(struct file *file, unsigned int cmd, unsigned long arg) +{ + struct therm therm; + union { + struct therm __user *therm; + int __user *i; + } uarg; + int i; + + uarg.i = (int __user *)arg; + + switch(cmd) { + case CMD_SET_THERMOSTATE: + case CMD_SET_THERMOSTATE2: + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + if (cmd == CMD_SET_THERMOSTATE) { + if (get_user(therm.hi, uarg.i)) + return -EFAULT; + therm.lo = therm.hi - 3; + } else { + if (copy_from_user(&therm, uarg.therm, sizeof(therm))) + return -EFAULT; + } + + therm.lo <<= 1; + therm.hi <<= 1; + + ds1620_write_state(&therm); + break; + + case CMD_GET_THERMOSTATE: + case CMD_GET_THERMOSTATE2: + ds1620_read_state(&therm); + + therm.lo >>= 1; + therm.hi >>= 1; + + if (cmd == CMD_GET_THERMOSTATE) { + if (put_user(therm.hi, uarg.i)) + return -EFAULT; + } else { + if (copy_to_user(uarg.therm, &therm, sizeof(therm))) + return -EFAULT; + } + break; + + case CMD_GET_TEMPERATURE: + case CMD_GET_TEMPERATURE2: + i = cvt_9_to_int(ds1620_in(THERM_READ_TEMP, 9)); + + if (cmd == CMD_GET_TEMPERATURE) + i >>= 1; + + return put_user(i, uarg.i) ? -EFAULT : 0; + + case CMD_GET_STATUS: + i = ds1620_in(THERM_READ_CONFIG, 8) & 0xe3; + + return put_user(i, uarg.i) ? -EFAULT : 0; + + case CMD_GET_FAN: + i = netwinder_get_fan(); + + return put_user(i, uarg.i) ? -EFAULT : 0; + + case CMD_SET_FAN: + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + if (get_user(i, uarg.i)) + return -EFAULT; + + netwinder_set_fan(i); + break; + + default: + return -ENOIOCTLCMD; + } + + return 0; +} + +static long +ds1620_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg) +{ + int ret; + + mutex_lock(&ds1620_mutex); + ret = ds1620_ioctl(file, cmd, arg); + mutex_unlock(&ds1620_mutex); + + return ret; +} + +#ifdef THERM_USE_PROC +static int ds1620_proc_therm_show(struct seq_file *m, void *v) +{ + struct therm th; + int temp; + + ds1620_read_state(&th); + temp = cvt_9_to_int(ds1620_in(THERM_READ_TEMP, 9)); + + seq_printf(m, "Thermostat: HI %i.%i, LOW %i.%i; temperature: %i.%i C, fan %s\n", + th.hi >> 1, th.hi & 1 ? 5 : 0, + th.lo >> 1, th.lo & 1 ? 5 : 0, + temp >> 1, temp & 1 ? 5 : 0, + fan_state[netwinder_get_fan()]); + return 0; +} +#endif + +static const struct file_operations ds1620_fops = { + .owner = THIS_MODULE, + .open = ds1620_open, + .read = ds1620_read, + .unlocked_ioctl = ds1620_unlocked_ioctl, +}; + +static struct miscdevice ds1620_miscdev = { + TEMP_MINOR, + "temp", + &ds1620_fops +}; + +static int __init ds1620_init(void) +{ + int ret; + struct therm th, th_start; + + if (!machine_is_netwinder()) + return -ENODEV; + + ds1620_out(THERM_RESET, 0, 0); + ds1620_out(THERM_WRITE_CONFIG, 8, CFG_CPU); + ds1620_out(THERM_START_CONVERT, 0, 0); + + /* + * Trigger the fan to start by setting + * temperature high point low. This kicks + * the fan into action. + */ + ds1620_read_state(&th); + th_start.lo = 0; + th_start.hi = 1; + ds1620_write_state(&th_start); + + msleep(2000); + + ds1620_write_state(&th); + + ret = misc_register(&ds1620_miscdev); + if (ret < 0) + return ret; + +#ifdef THERM_USE_PROC + if (!proc_create_single("therm", 0, NULL, ds1620_proc_therm_show)) + printk(KERN_ERR "therm: unable to register /proc/therm\n"); +#endif + + ds1620_read_state(&th); + ret = cvt_9_to_int(ds1620_in(THERM_READ_TEMP, 9)); + + printk(KERN_INFO "Thermostat: high %i.%i, low %i.%i, " + "current %i.%i C, fan %s.\n", + th.hi >> 1, th.hi & 1 ? 5 : 0, + th.lo >> 1, th.lo & 1 ? 5 : 0, + ret >> 1, ret & 1 ? 5 : 0, + fan_state[netwinder_get_fan()]); + + return 0; +} + +static void __exit ds1620_exit(void) +{ +#ifdef THERM_USE_PROC + remove_proc_entry("therm", NULL); +#endif + misc_deregister(&ds1620_miscdev); +} + +module_init(ds1620_init); +module_exit(ds1620_exit); + +MODULE_DESCRIPTION("Dallas Semiconductor DS1620 thermometer driver"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1