linux/drivers/leds/led-core.c
Hans de Goede 22720a87d0 leds: Fix oops about sleeping in led_trigger_blink()
led_trigger_blink() calls led_blink_set() from a RCU read-side critical
section so led_blink_set() must not sleep. Note sleeping was not allowed
before the switch to RCU either because a spinlock was held before.

led_blink_set() does not sleep when sw-blinking is used, but
many LED controller drivers with hw blink support have a blink_set
function which may sleep, leading to an oops like this one:

[  832.605062] ------------[ cut here ]------------
[  832.605085] Voluntary context switch within RCU read-side critical section!
[  832.605119] WARNING: CPU: 2 PID: 370 at kernel/rcu/tree_plugin.h:318 rcu_note_context_switch+0x4ee/0x690
<snip>
[  832.606453] Call Trace:
[  832.606466]  <TASK>
[  832.606487]  __schedule+0x9f/0x1480
[  832.606527]  schedule+0x5d/0xe0
[  832.606549]  schedule_timeout+0x79/0x140
[  832.606572]  ? __pfx_process_timeout+0x10/0x10
[  832.606599]  wait_for_completion_timeout+0x6f/0x140
[  832.606627]  i2c_dw_xfer+0x101/0x460
[  832.606659]  ? psi_group_change+0x168/0x400
[  832.606680]  __i2c_transfer+0x172/0x6d0
[  832.606709]  i2c_smbus_xfer_emulated+0x27d/0x9c0
[  832.606732]  ? __schedule+0x430/0x1480
[  832.606753]  ? preempt_count_add+0x6a/0xa0
[  832.606778]  ? get_nohz_timer_target+0x18/0x190
[  832.606796]  ? lock_timer_base+0x61/0x80
[  832.606817]  ? preempt_count_add+0x6a/0xa0
[  832.606842]  __i2c_smbus_xfer+0xa2/0x3f0
[  832.606862]  i2c_smbus_xfer+0x66/0xf0
[  832.606882]  i2c_smbus_read_byte_data+0x41/0x70
[  832.606901]  ? _raw_spin_unlock_irqrestore+0x23/0x40
[  832.606922]  ? __pm_runtime_suspend+0x46/0xc0
[  832.606946]  cht_wc_byte_reg_read+0x2e/0x60
[  832.606972]  _regmap_read+0x5c/0x120
[  832.606997]  _regmap_update_bits+0x96/0xc0
[  832.607023]  regmap_update_bits_base+0x5b/0x90
[  832.607053]  cht_wc_leds_brightness_get+0x412/0x910 [leds_cht_wcove]
[  832.607094]  led_blink_setup+0x28/0x100
[  832.607119]  led_trigger_blink+0x40/0x70
[  832.607145]  power_supply_update_leds+0x1b7/0x1c0
[  832.607174]  power_supply_changed_work+0x67/0xe0
[  832.607198]  process_one_work+0x1c8/0x3c0
[  832.607222]  worker_thread+0x4d/0x380
[  832.607243]  ? __pfx_worker_thread+0x10/0x10
[  832.607258]  kthread+0xe9/0x110
[  832.607279]  ? __pfx_kthread+0x10/0x10
[  832.607300]  ret_from_fork+0x2c/0x50
[  832.607337]  </TASK>
[  832.607344] ---[ end trace 0000000000000000 ]---

Add a new led_blink_set_nosleep() function which defers the actual
led_blink_set() call to a workqueue when necessary to fix this.

This also fixes an existing race where a pending led_set_brightness() has
been deferred to set_brightness_work and might then race with a later
led_cdev->blink_set() call. Note this race is only an issue with triggers
mixing led_trigger_event() and led_trigger_blink() calls, sysfs API
calls and led_trigger_blink_oneshot() are not affected.

Note rather then adding a separate blink_set_blocking callback this uses
the presence of the already existing brightness_set_blocking callback to
detect if the blinking call should be deferred to set_brightness_work.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Tested-by: Yauhen Kharuzhy <jekhor@gmail.com>
Link: https://lore.kernel.org/r/20230510162234.291439-4-hdegoede@redhat.com
Signed-off-by: Lee Jones <lee@kernel.org>
2023-05-25 12:16:31 +01:00

550 lines
15 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* LED Class Core
*
* Copyright 2005-2006 Openedhand Ltd.
*
* Author: Richard Purdie <rpurdie@openedhand.com>
*/
#include <linux/kernel.h>
#include <linux/leds.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/property.h>
#include <linux/rwsem.h>
#include <linux/slab.h>
#include <uapi/linux/uleds.h>
#include "leds.h"
DECLARE_RWSEM(leds_list_lock);
EXPORT_SYMBOL_GPL(leds_list_lock);
LIST_HEAD(leds_list);
EXPORT_SYMBOL_GPL(leds_list);
const char * const led_colors[LED_COLOR_ID_MAX] = {
[LED_COLOR_ID_WHITE] = "white",
[LED_COLOR_ID_RED] = "red",
[LED_COLOR_ID_GREEN] = "green",
[LED_COLOR_ID_BLUE] = "blue",
[LED_COLOR_ID_AMBER] = "amber",
[LED_COLOR_ID_VIOLET] = "violet",
[LED_COLOR_ID_YELLOW] = "yellow",
[LED_COLOR_ID_IR] = "ir",
[LED_COLOR_ID_MULTI] = "multicolor",
[LED_COLOR_ID_RGB] = "rgb",
};
EXPORT_SYMBOL_GPL(led_colors);
static int __led_set_brightness(struct led_classdev *led_cdev, unsigned int value)
{
if (!led_cdev->brightness_set)
return -ENOTSUPP;
led_cdev->brightness_set(led_cdev, value);
return 0;
}
static int __led_set_brightness_blocking(struct led_classdev *led_cdev, unsigned int value)
{
if (!led_cdev->brightness_set_blocking)
return -ENOTSUPP;
return led_cdev->brightness_set_blocking(led_cdev, value);
}
static void led_timer_function(struct timer_list *t)
{
struct led_classdev *led_cdev = from_timer(led_cdev, t, blink_timer);
unsigned long brightness;
unsigned long delay;
if (!led_cdev->blink_delay_on || !led_cdev->blink_delay_off) {
led_set_brightness_nosleep(led_cdev, LED_OFF);
clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
return;
}
if (test_and_clear_bit(LED_BLINK_ONESHOT_STOP,
&led_cdev->work_flags)) {
clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
return;
}
brightness = led_get_brightness(led_cdev);
if (!brightness) {
/* Time to switch the LED on. */
if (test_and_clear_bit(LED_BLINK_BRIGHTNESS_CHANGE,
&led_cdev->work_flags))
brightness = led_cdev->new_blink_brightness;
else
brightness = led_cdev->blink_brightness;
delay = led_cdev->blink_delay_on;
} else {
/* Store the current brightness value to be able
* to restore it when the delay_off period is over.
*/
led_cdev->blink_brightness = brightness;
brightness = LED_OFF;
delay = led_cdev->blink_delay_off;
}
led_set_brightness_nosleep(led_cdev, brightness);
/* Return in next iteration if led is in one-shot mode and we are in
* the final blink state so that the led is toggled each delay_on +
* delay_off milliseconds in worst case.
*/
if (test_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags)) {
if (test_bit(LED_BLINK_INVERT, &led_cdev->work_flags)) {
if (brightness)
set_bit(LED_BLINK_ONESHOT_STOP,
&led_cdev->work_flags);
} else {
if (!brightness)
set_bit(LED_BLINK_ONESHOT_STOP,
&led_cdev->work_flags);
}
}
mod_timer(&led_cdev->blink_timer, jiffies + msecs_to_jiffies(delay));
}
static void set_brightness_delayed_set_brightness(struct led_classdev *led_cdev,
unsigned int value)
{
int ret = 0;
ret = __led_set_brightness(led_cdev, value);
if (ret == -ENOTSUPP)
ret = __led_set_brightness_blocking(led_cdev, value);
if (ret < 0 &&
/* LED HW might have been unplugged, therefore don't warn */
!(ret == -ENODEV && (led_cdev->flags & LED_UNREGISTERING) &&
(led_cdev->flags & LED_HW_PLUGGABLE)))
dev_err(led_cdev->dev,
"Setting an LED's brightness failed (%d)\n", ret);
}
static void set_brightness_delayed(struct work_struct *ws)
{
struct led_classdev *led_cdev =
container_of(ws, struct led_classdev, set_brightness_work);
if (test_and_clear_bit(LED_BLINK_DISABLE, &led_cdev->work_flags)) {
led_stop_software_blink(led_cdev);
set_bit(LED_SET_BRIGHTNESS_OFF, &led_cdev->work_flags);
}
/*
* Triggers may call led_set_brightness(LED_OFF),
* led_set_brightness(LED_FULL) in quick succession to disable blinking
* and turn the LED on. Both actions may have been scheduled to run
* before this work item runs once. To make sure this works properly
* handle LED_SET_BRIGHTNESS_OFF first.
*/
if (test_and_clear_bit(LED_SET_BRIGHTNESS_OFF, &led_cdev->work_flags))
set_brightness_delayed_set_brightness(led_cdev, LED_OFF);
if (test_and_clear_bit(LED_SET_BRIGHTNESS, &led_cdev->work_flags))
set_brightness_delayed_set_brightness(led_cdev, led_cdev->delayed_set_value);
if (test_and_clear_bit(LED_SET_BLINK, &led_cdev->work_flags)) {
unsigned long delay_on = led_cdev->delayed_delay_on;
unsigned long delay_off = led_cdev->delayed_delay_off;
led_blink_set(led_cdev, &delay_on, &delay_off);
}
}
static void led_set_software_blink(struct led_classdev *led_cdev,
unsigned long delay_on,
unsigned long delay_off)
{
int current_brightness;
current_brightness = led_get_brightness(led_cdev);
if (current_brightness)
led_cdev->blink_brightness = current_brightness;
if (!led_cdev->blink_brightness)
led_cdev->blink_brightness = led_cdev->max_brightness;
led_cdev->blink_delay_on = delay_on;
led_cdev->blink_delay_off = delay_off;
/* never on - just set to off */
if (!delay_on) {
led_set_brightness_nosleep(led_cdev, LED_OFF);
return;
}
/* never off - just set to brightness */
if (!delay_off) {
led_set_brightness_nosleep(led_cdev,
led_cdev->blink_brightness);
return;
}
set_bit(LED_BLINK_SW, &led_cdev->work_flags);
mod_timer(&led_cdev->blink_timer, jiffies + 1);
}
static void led_blink_setup(struct led_classdev *led_cdev,
unsigned long *delay_on,
unsigned long *delay_off)
{
if (!test_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags) &&
led_cdev->blink_set &&
!led_cdev->blink_set(led_cdev, delay_on, delay_off))
return;
/* blink with 1 Hz as default if nothing specified */
if (!*delay_on && !*delay_off)
*delay_on = *delay_off = 500;
led_set_software_blink(led_cdev, *delay_on, *delay_off);
}
void led_init_core(struct led_classdev *led_cdev)
{
INIT_WORK(&led_cdev->set_brightness_work, set_brightness_delayed);
timer_setup(&led_cdev->blink_timer, led_timer_function, 0);
}
EXPORT_SYMBOL_GPL(led_init_core);
void led_blink_set(struct led_classdev *led_cdev,
unsigned long *delay_on,
unsigned long *delay_off)
{
del_timer_sync(&led_cdev->blink_timer);
clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
clear_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags);
clear_bit(LED_BLINK_ONESHOT_STOP, &led_cdev->work_flags);
led_blink_setup(led_cdev, delay_on, delay_off);
}
EXPORT_SYMBOL_GPL(led_blink_set);
void led_blink_set_oneshot(struct led_classdev *led_cdev,
unsigned long *delay_on,
unsigned long *delay_off,
int invert)
{
if (test_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags) &&
timer_pending(&led_cdev->blink_timer))
return;
set_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags);
clear_bit(LED_BLINK_ONESHOT_STOP, &led_cdev->work_flags);
if (invert)
set_bit(LED_BLINK_INVERT, &led_cdev->work_flags);
else
clear_bit(LED_BLINK_INVERT, &led_cdev->work_flags);
led_blink_setup(led_cdev, delay_on, delay_off);
}
EXPORT_SYMBOL_GPL(led_blink_set_oneshot);
void led_blink_set_nosleep(struct led_classdev *led_cdev, unsigned long delay_on,
unsigned long delay_off)
{
/* If necessary delegate to a work queue task. */
if (led_cdev->blink_set && led_cdev->brightness_set_blocking) {
led_cdev->delayed_delay_on = delay_on;
led_cdev->delayed_delay_off = delay_off;
set_bit(LED_SET_BLINK, &led_cdev->work_flags);
schedule_work(&led_cdev->set_brightness_work);
return;
}
led_blink_set(led_cdev, &delay_on, &delay_off);
}
EXPORT_SYMBOL_GPL(led_blink_set_nosleep);
void led_stop_software_blink(struct led_classdev *led_cdev)
{
del_timer_sync(&led_cdev->blink_timer);
led_cdev->blink_delay_on = 0;
led_cdev->blink_delay_off = 0;
clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
}
EXPORT_SYMBOL_GPL(led_stop_software_blink);
void led_set_brightness(struct led_classdev *led_cdev, unsigned int brightness)
{
/*
* If software blink is active, delay brightness setting
* until the next timer tick.
*/
if (test_bit(LED_BLINK_SW, &led_cdev->work_flags)) {
/*
* If we need to disable soft blinking delegate this to the
* work queue task to avoid problems in case we are called
* from hard irq context.
*/
if (!brightness) {
set_bit(LED_BLINK_DISABLE, &led_cdev->work_flags);
schedule_work(&led_cdev->set_brightness_work);
} else {
set_bit(LED_BLINK_BRIGHTNESS_CHANGE,
&led_cdev->work_flags);
led_cdev->new_blink_brightness = brightness;
}
return;
}
led_set_brightness_nosleep(led_cdev, brightness);
}
EXPORT_SYMBOL_GPL(led_set_brightness);
void led_set_brightness_nopm(struct led_classdev *led_cdev, unsigned int value)
{
/* Use brightness_set op if available, it is guaranteed not to sleep */
if (!__led_set_brightness(led_cdev, value))
return;
/*
* Brightness setting can sleep, delegate it to a work queue task.
* value 0 / LED_OFF is special, since it also disables hw-blinking
* (sw-blink disable is handled in led_set_brightness()).
* To avoid a hw-blink-disable getting lost when a second brightness
* change is done immediately afterwards (before the work runs),
* it uses a separate work_flag.
*/
if (value) {
led_cdev->delayed_set_value = value;
set_bit(LED_SET_BRIGHTNESS, &led_cdev->work_flags);
} else {
clear_bit(LED_SET_BRIGHTNESS, &led_cdev->work_flags);
clear_bit(LED_SET_BLINK, &led_cdev->work_flags);
set_bit(LED_SET_BRIGHTNESS_OFF, &led_cdev->work_flags);
}
schedule_work(&led_cdev->set_brightness_work);
}
EXPORT_SYMBOL_GPL(led_set_brightness_nopm);
void led_set_brightness_nosleep(struct led_classdev *led_cdev, unsigned int value)
{
led_cdev->brightness = min(value, led_cdev->max_brightness);
if (led_cdev->flags & LED_SUSPENDED)
return;
led_set_brightness_nopm(led_cdev, led_cdev->brightness);
}
EXPORT_SYMBOL_GPL(led_set_brightness_nosleep);
int led_set_brightness_sync(struct led_classdev *led_cdev, unsigned int value)
{
if (led_cdev->blink_delay_on || led_cdev->blink_delay_off)
return -EBUSY;
led_cdev->brightness = min(value, led_cdev->max_brightness);
if (led_cdev->flags & LED_SUSPENDED)
return 0;
return __led_set_brightness_blocking(led_cdev, led_cdev->brightness);
}
EXPORT_SYMBOL_GPL(led_set_brightness_sync);
int led_update_brightness(struct led_classdev *led_cdev)
{
int ret = 0;
if (led_cdev->brightness_get) {
ret = led_cdev->brightness_get(led_cdev);
if (ret >= 0) {
led_cdev->brightness = ret;
return 0;
}
}
return ret;
}
EXPORT_SYMBOL_GPL(led_update_brightness);
u32 *led_get_default_pattern(struct led_classdev *led_cdev, unsigned int *size)
{
struct fwnode_handle *fwnode = led_cdev->dev->fwnode;
u32 *pattern;
int count;
count = fwnode_property_count_u32(fwnode, "led-pattern");
if (count < 0)
return NULL;
pattern = kcalloc(count, sizeof(*pattern), GFP_KERNEL);
if (!pattern)
return NULL;
if (fwnode_property_read_u32_array(fwnode, "led-pattern", pattern, count)) {
kfree(pattern);
return NULL;
}
*size = count;
return pattern;
}
EXPORT_SYMBOL_GPL(led_get_default_pattern);
/* Caller must ensure led_cdev->led_access held */
void led_sysfs_disable(struct led_classdev *led_cdev)
{
lockdep_assert_held(&led_cdev->led_access);
led_cdev->flags |= LED_SYSFS_DISABLE;
}
EXPORT_SYMBOL_GPL(led_sysfs_disable);
/* Caller must ensure led_cdev->led_access held */
void led_sysfs_enable(struct led_classdev *led_cdev)
{
lockdep_assert_held(&led_cdev->led_access);
led_cdev->flags &= ~LED_SYSFS_DISABLE;
}
EXPORT_SYMBOL_GPL(led_sysfs_enable);
static void led_parse_fwnode_props(struct device *dev,
struct fwnode_handle *fwnode,
struct led_properties *props)
{
int ret;
if (!fwnode)
return;
if (fwnode_property_present(fwnode, "label")) {
ret = fwnode_property_read_string(fwnode, "label", &props->label);
if (ret)
dev_err(dev, "Error parsing 'label' property (%d)\n", ret);
return;
}
if (fwnode_property_present(fwnode, "color")) {
ret = fwnode_property_read_u32(fwnode, "color", &props->color);
if (ret)
dev_err(dev, "Error parsing 'color' property (%d)\n", ret);
else if (props->color >= LED_COLOR_ID_MAX)
dev_err(dev, "LED color identifier out of range\n");
else
props->color_present = true;
}
if (!fwnode_property_present(fwnode, "function"))
return;
ret = fwnode_property_read_string(fwnode, "function", &props->function);
if (ret) {
dev_err(dev,
"Error parsing 'function' property (%d)\n",
ret);
}
if (!fwnode_property_present(fwnode, "function-enumerator"))
return;
ret = fwnode_property_read_u32(fwnode, "function-enumerator",
&props->func_enum);
if (ret) {
dev_err(dev,
"Error parsing 'function-enumerator' property (%d)\n",
ret);
} else {
props->func_enum_present = true;
}
}
int led_compose_name(struct device *dev, struct led_init_data *init_data,
char *led_classdev_name)
{
struct led_properties props = {};
struct fwnode_handle *fwnode = init_data->fwnode;
const char *devicename = init_data->devicename;
/* We want to label LEDs that can produce full range of colors
* as RGB, not multicolor */
BUG_ON(props.color == LED_COLOR_ID_MULTI);
if (!led_classdev_name)
return -EINVAL;
led_parse_fwnode_props(dev, fwnode, &props);
if (props.label) {
/*
* If init_data.devicename is NULL, then it indicates that
* DT label should be used as-is for LED class device name.
* Otherwise the label is prepended with devicename to compose
* the final LED class device name.
*/
if (!devicename) {
strscpy(led_classdev_name, props.label,
LED_MAX_NAME_SIZE);
} else {
snprintf(led_classdev_name, LED_MAX_NAME_SIZE, "%s:%s",
devicename, props.label);
}
} else if (props.function || props.color_present) {
char tmp_buf[LED_MAX_NAME_SIZE];
if (props.func_enum_present) {
snprintf(tmp_buf, LED_MAX_NAME_SIZE, "%s:%s-%d",
props.color_present ? led_colors[props.color] : "",
props.function ?: "", props.func_enum);
} else {
snprintf(tmp_buf, LED_MAX_NAME_SIZE, "%s:%s",
props.color_present ? led_colors[props.color] : "",
props.function ?: "");
}
if (init_data->devname_mandatory) {
snprintf(led_classdev_name, LED_MAX_NAME_SIZE, "%s:%s",
devicename, tmp_buf);
} else {
strscpy(led_classdev_name, tmp_buf, LED_MAX_NAME_SIZE);
}
} else if (init_data->default_label) {
if (!devicename) {
dev_err(dev, "Legacy LED naming requires devicename segment");
return -EINVAL;
}
snprintf(led_classdev_name, LED_MAX_NAME_SIZE, "%s:%s",
devicename, init_data->default_label);
} else if (is_of_node(fwnode)) {
strscpy(led_classdev_name, to_of_node(fwnode)->name,
LED_MAX_NAME_SIZE);
} else
return -EINVAL;
return 0;
}
EXPORT_SYMBOL_GPL(led_compose_name);
enum led_default_state led_init_default_state_get(struct fwnode_handle *fwnode)
{
const char *state = NULL;
if (!fwnode_property_read_string(fwnode, "default-state", &state)) {
if (!strcmp(state, "keep"))
return LEDS_DEFSTATE_KEEP;
if (!strcmp(state, "on"))
return LEDS_DEFSTATE_ON;
}
return LEDS_DEFSTATE_OFF;
}
EXPORT_SYMBOL_GPL(led_init_default_state_get);