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![Andrea Righi](/assets/img/avatar_default.png)
We have the following potential deadlock condition: ======================================================== WARNING: possible irq lock inversion dependency detected 5.10.0-rc2+ #25 Not tainted -------------------------------------------------------- swapper/3/0 just changed the state of lock: ffff8880063bd618 (&host->lock){-...}-{2:2}, at: ata_bmdma_interrupt+0x27/0x200 but this lock took another, HARDIRQ-READ-unsafe lock in the past: (&trig->leddev_list_lock){.+.?}-{2:2} and interrupts could create inverse lock ordering between them. other info that might help us debug this: Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&trig->leddev_list_lock); local_irq_disable(); lock(&host->lock); lock(&trig->leddev_list_lock); <Interrupt> lock(&host->lock); *** DEADLOCK *** no locks held by swapper/3/0. the shortest dependencies between 2nd lock and 1st lock: -> (&trig->leddev_list_lock){.+.?}-{2:2} ops: 46 { HARDIRQ-ON-R at: lock_acquire+0x15f/0x420 _raw_read_lock+0x42/0x90 led_trigger_event+0x2b/0x70 rfkill_global_led_trigger_worker+0x94/0xb0 process_one_work+0x240/0x560 worker_thread+0x58/0x3d0 kthread+0x151/0x170 ret_from_fork+0x1f/0x30 IN-SOFTIRQ-R at: lock_acquire+0x15f/0x420 _raw_read_lock+0x42/0x90 led_trigger_event+0x2b/0x70 kbd_bh+0x9e/0xc0 tasklet_action_common.constprop.0+0xe9/0x100 tasklet_action+0x22/0x30 __do_softirq+0xcc/0x46d run_ksoftirqd+0x3f/0x70 smpboot_thread_fn+0x116/0x1f0 kthread+0x151/0x170 ret_from_fork+0x1f/0x30 SOFTIRQ-ON-R at: lock_acquire+0x15f/0x420 _raw_read_lock+0x42/0x90 led_trigger_event+0x2b/0x70 rfkill_global_led_trigger_worker+0x94/0xb0 process_one_work+0x240/0x560 worker_thread+0x58/0x3d0 kthread+0x151/0x170 ret_from_fork+0x1f/0x30 INITIAL READ USE at: lock_acquire+0x15f/0x420 _raw_read_lock+0x42/0x90 led_trigger_event+0x2b/0x70 rfkill_global_led_trigger_worker+0x94/0xb0 process_one_work+0x240/0x560 worker_thread+0x58/0x3d0 kthread+0x151/0x170 ret_from_fork+0x1f/0x30 } ... key at: [<ffffffff83da4c00>] __key.0+0x0/0x10 ... acquired at: _raw_read_lock+0x42/0x90 led_trigger_blink_oneshot+0x3b/0x90 ledtrig_disk_activity+0x3c/0xa0 ata_qc_complete+0x26/0x450 ata_do_link_abort+0xa3/0xe0 ata_port_freeze+0x2e/0x40 ata_hsm_qc_complete+0x94/0xa0 ata_sff_hsm_move+0x177/0x7a0 ata_sff_pio_task+0xc7/0x1b0 process_one_work+0x240/0x560 worker_thread+0x58/0x3d0 kthread+0x151/0x170 ret_from_fork+0x1f/0x30 -> (&host->lock){-...}-{2:2} ops: 69 { IN-HARDIRQ-W at: lock_acquire+0x15f/0x420 _raw_spin_lock_irqsave+0x52/0xa0 ata_bmdma_interrupt+0x27/0x200 __handle_irq_event_percpu+0xd5/0x2b0 handle_irq_event+0x57/0xb0 handle_edge_irq+0x8c/0x230 asm_call_irq_on_stack+0xf/0x20 common_interrupt+0x100/0x1c0 asm_common_interrupt+0x1e/0x40 native_safe_halt+0xe/0x10 arch_cpu_idle+0x15/0x20 default_idle_call+0x59/0x1c0 do_idle+0x22c/0x2c0 cpu_startup_entry+0x20/0x30 start_secondary+0x11d/0x150 secondary_startup_64_no_verify+0xa6/0xab INITIAL USE at: lock_acquire+0x15f/0x420 _raw_spin_lock_irqsave+0x52/0xa0 ata_dev_init+0x54/0xe0 ata_link_init+0x8b/0xd0 ata_port_alloc+0x1f1/0x210 ata_host_alloc+0xf1/0x130 ata_host_alloc_pinfo+0x14/0xb0 ata_pci_sff_prepare_host+0x41/0xa0 ata_pci_bmdma_prepare_host+0x14/0x30 piix_init_one+0x21f/0x600 local_pci_probe+0x48/0x80 pci_device_probe+0x105/0x1c0 really_probe+0x221/0x490 driver_probe_device+0xe9/0x160 device_driver_attach+0xb2/0xc0 __driver_attach+0x91/0x150 bus_for_each_dev+0x81/0xc0 driver_attach+0x1e/0x20 bus_add_driver+0x138/0x1f0 driver_register+0x91/0xf0 __pci_register_driver+0x73/0x80 piix_init+0x1e/0x2e do_one_initcall+0x5f/0x2d0 kernel_init_freeable+0x26f/0x2cf kernel_init+0xe/0x113 ret_from_fork+0x1f/0x30 } ... key at: [<ffffffff83d9fdc0>] __key.6+0x0/0x10 ... acquired at: __lock_acquire+0x9da/0x2370 lock_acquire+0x15f/0x420 _raw_spin_lock_irqsave+0x52/0xa0 ata_bmdma_interrupt+0x27/0x200 __handle_irq_event_percpu+0xd5/0x2b0 handle_irq_event+0x57/0xb0 handle_edge_irq+0x8c/0x230 asm_call_irq_on_stack+0xf/0x20 common_interrupt+0x100/0x1c0 asm_common_interrupt+0x1e/0x40 native_safe_halt+0xe/0x10 arch_cpu_idle+0x15/0x20 default_idle_call+0x59/0x1c0 do_idle+0x22c/0x2c0 cpu_startup_entry+0x20/0x30 start_secondary+0x11d/0x150 secondary_startup_64_no_verify+0xa6/0xab This lockdep splat is reported after: commite918188611
("locking: More accurate annotations for read_lock()") To clarify: - read-locks are recursive only in interrupt context (when in_interrupt() returns true) - after acquiring host->lock in CPU1, another cpu (i.e. CPU2) may call write_lock(&trig->leddev_list_lock) that would be blocked by CPU0 that holds trig->leddev_list_lock in read-mode - when CPU1 (ata_ac_complete()) tries to read-lock trig->leddev_list_lock, it would be blocked by the write-lock waiter on CPU2 (because we are not in interrupt context, so the read-lock is not recursive) - at this point if an interrupt happens on CPU0 and ata_bmdma_interrupt() is executed it will try to acquire host->lock, that is held by CPU1, that is currently blocked by CPU2, so: * CPU0 blocked by CPU1 * CPU1 blocked by CPU2 * CPU2 blocked by CPU0 *** DEADLOCK *** The deadlock scenario is better represented by the following schema (thanks to Boqun Feng <boqun.feng@gmail.com> for the schema and the detailed explanation of the deadlock condition): CPU 0: CPU 1: CPU 2: ----- ----- ----- led_trigger_event(): read_lock(&trig->leddev_list_lock); <workqueue> ata_hsm_qc_complete(): spin_lock_irqsave(&host->lock); write_lock(&trig->leddev_list_lock); ata_port_freeze(): ata_do_link_abort(): ata_qc_complete(): ledtrig_disk_activity(): led_trigger_blink_oneshot(): read_lock(&trig->leddev_list_lock); // ^ not in in_interrupt() context, so could get blocked by CPU 2 <interrupt> ata_bmdma_interrupt(): spin_lock_irqsave(&host->lock); Fix by using read_lock_irqsave/irqrestore() in led_trigger_event(), so that no interrupt can happen in between, preventing the deadlock condition. Apply the same change to led_trigger_blink_setup() as well, since the same deadlock scenario can also happen in power_supply_update_bat_leds() -> led_trigger_blink() -> led_trigger_blink_setup() (workqueue context), and potentially prevent other similar usages. Link: https://lore.kernel.org/lkml/20201101092614.GB3989@xps-13-7390/ Fixes:eb25cb9956
("leds: convert IDE trigger to common disk trigger") Signed-off-by: Andrea Righi <andrea.righi@canonical.com> Signed-off-by: Pavel Machek <pavel@ucw.cz>
463 lines
11 KiB
C
463 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* LED Triggers Core
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*
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* Copyright 2005-2007 Openedhand Ltd.
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*
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* Author: Richard Purdie <rpurdie@openedhand.com>
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*/
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#include <linux/export.h>
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/spinlock.h>
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#include <linux/device.h>
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#include <linux/timer.h>
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#include <linux/rwsem.h>
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#include <linux/leds.h>
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#include <linux/slab.h>
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#include <linux/mm.h>
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#include "leds.h"
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/*
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* Nests outside led_cdev->trigger_lock
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*/
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static DECLARE_RWSEM(triggers_list_lock);
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LIST_HEAD(trigger_list);
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/* Used by LED Class */
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static inline bool
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trigger_relevant(struct led_classdev *led_cdev, struct led_trigger *trig)
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{
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return !trig->trigger_type || trig->trigger_type == led_cdev->trigger_type;
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}
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ssize_t led_trigger_write(struct file *filp, struct kobject *kobj,
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struct bin_attribute *bin_attr, char *buf,
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loff_t pos, size_t count)
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{
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struct device *dev = kobj_to_dev(kobj);
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struct led_classdev *led_cdev = dev_get_drvdata(dev);
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struct led_trigger *trig;
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int ret = count;
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mutex_lock(&led_cdev->led_access);
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if (led_sysfs_is_disabled(led_cdev)) {
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ret = -EBUSY;
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goto unlock;
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}
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if (sysfs_streq(buf, "none")) {
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led_trigger_remove(led_cdev);
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goto unlock;
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}
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down_read(&triggers_list_lock);
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list_for_each_entry(trig, &trigger_list, next_trig) {
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if (sysfs_streq(buf, trig->name) && trigger_relevant(led_cdev, trig)) {
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down_write(&led_cdev->trigger_lock);
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led_trigger_set(led_cdev, trig);
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up_write(&led_cdev->trigger_lock);
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up_read(&triggers_list_lock);
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goto unlock;
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}
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}
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/* we come here only if buf matches no trigger */
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ret = -EINVAL;
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up_read(&triggers_list_lock);
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unlock:
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mutex_unlock(&led_cdev->led_access);
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return ret;
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}
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EXPORT_SYMBOL_GPL(led_trigger_write);
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__printf(3, 4)
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static int led_trigger_snprintf(char *buf, ssize_t size, const char *fmt, ...)
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{
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va_list args;
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int i;
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va_start(args, fmt);
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if (size <= 0)
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i = vsnprintf(NULL, 0, fmt, args);
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else
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i = vscnprintf(buf, size, fmt, args);
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va_end(args);
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return i;
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}
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static int led_trigger_format(char *buf, size_t size,
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struct led_classdev *led_cdev)
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{
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struct led_trigger *trig;
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int len = led_trigger_snprintf(buf, size, "%s",
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led_cdev->trigger ? "none" : "[none]");
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list_for_each_entry(trig, &trigger_list, next_trig) {
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bool hit;
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if (!trigger_relevant(led_cdev, trig))
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continue;
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hit = led_cdev->trigger && !strcmp(led_cdev->trigger->name, trig->name);
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len += led_trigger_snprintf(buf + len, size - len,
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" %s%s%s", hit ? "[" : "",
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trig->name, hit ? "]" : "");
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}
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len += led_trigger_snprintf(buf + len, size - len, "\n");
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return len;
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}
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/*
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* It was stupid to create 10000 cpu triggers, but we are stuck with it now.
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* Don't make that mistake again. We work around it here by creating binary
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* attribute, which is not limited by length. This is _not_ good design, do not
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* copy it.
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*/
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ssize_t led_trigger_read(struct file *filp, struct kobject *kobj,
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struct bin_attribute *attr, char *buf,
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loff_t pos, size_t count)
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{
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struct device *dev = kobj_to_dev(kobj);
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struct led_classdev *led_cdev = dev_get_drvdata(dev);
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void *data;
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int len;
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down_read(&triggers_list_lock);
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down_read(&led_cdev->trigger_lock);
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len = led_trigger_format(NULL, 0, led_cdev);
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data = kvmalloc(len + 1, GFP_KERNEL);
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if (!data) {
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up_read(&led_cdev->trigger_lock);
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up_read(&triggers_list_lock);
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return -ENOMEM;
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}
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len = led_trigger_format(data, len + 1, led_cdev);
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up_read(&led_cdev->trigger_lock);
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up_read(&triggers_list_lock);
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len = memory_read_from_buffer(buf, count, &pos, data, len);
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kvfree(data);
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return len;
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}
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EXPORT_SYMBOL_GPL(led_trigger_read);
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/* Caller must ensure led_cdev->trigger_lock held */
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int led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig)
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{
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unsigned long flags;
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char *event = NULL;
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char *envp[2];
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const char *name;
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int ret;
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if (!led_cdev->trigger && !trig)
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return 0;
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name = trig ? trig->name : "none";
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event = kasprintf(GFP_KERNEL, "TRIGGER=%s", name);
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/* Remove any existing trigger */
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if (led_cdev->trigger) {
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write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags);
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list_del(&led_cdev->trig_list);
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write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock,
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flags);
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cancel_work_sync(&led_cdev->set_brightness_work);
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led_stop_software_blink(led_cdev);
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if (led_cdev->trigger->deactivate)
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led_cdev->trigger->deactivate(led_cdev);
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device_remove_groups(led_cdev->dev, led_cdev->trigger->groups);
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led_cdev->trigger = NULL;
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led_cdev->trigger_data = NULL;
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led_cdev->activated = false;
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led_set_brightness(led_cdev, LED_OFF);
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}
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if (trig) {
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write_lock_irqsave(&trig->leddev_list_lock, flags);
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list_add_tail(&led_cdev->trig_list, &trig->led_cdevs);
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write_unlock_irqrestore(&trig->leddev_list_lock, flags);
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led_cdev->trigger = trig;
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if (trig->activate)
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ret = trig->activate(led_cdev);
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else
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ret = 0;
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if (ret)
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goto err_activate;
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ret = device_add_groups(led_cdev->dev, trig->groups);
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if (ret) {
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dev_err(led_cdev->dev, "Failed to add trigger attributes\n");
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goto err_add_groups;
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}
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}
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if (event) {
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envp[0] = event;
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envp[1] = NULL;
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if (kobject_uevent_env(&led_cdev->dev->kobj, KOBJ_CHANGE, envp))
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dev_err(led_cdev->dev,
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"%s: Error sending uevent\n", __func__);
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kfree(event);
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}
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return 0;
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err_add_groups:
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if (trig->deactivate)
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trig->deactivate(led_cdev);
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err_activate:
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write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags);
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list_del(&led_cdev->trig_list);
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write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock, flags);
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led_cdev->trigger = NULL;
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led_cdev->trigger_data = NULL;
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led_set_brightness(led_cdev, LED_OFF);
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kfree(event);
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return ret;
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}
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EXPORT_SYMBOL_GPL(led_trigger_set);
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void led_trigger_remove(struct led_classdev *led_cdev)
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{
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down_write(&led_cdev->trigger_lock);
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led_trigger_set(led_cdev, NULL);
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up_write(&led_cdev->trigger_lock);
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}
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EXPORT_SYMBOL_GPL(led_trigger_remove);
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void led_trigger_set_default(struct led_classdev *led_cdev)
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{
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struct led_trigger *trig;
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if (!led_cdev->default_trigger)
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return;
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down_read(&triggers_list_lock);
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down_write(&led_cdev->trigger_lock);
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list_for_each_entry(trig, &trigger_list, next_trig) {
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if (!strcmp(led_cdev->default_trigger, trig->name) &&
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trigger_relevant(led_cdev, trig)) {
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led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
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led_trigger_set(led_cdev, trig);
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break;
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}
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}
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up_write(&led_cdev->trigger_lock);
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up_read(&triggers_list_lock);
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}
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EXPORT_SYMBOL_GPL(led_trigger_set_default);
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void led_trigger_rename_static(const char *name, struct led_trigger *trig)
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{
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/* new name must be on a temporary string to prevent races */
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BUG_ON(name == trig->name);
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down_write(&triggers_list_lock);
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/* this assumes that trig->name was originaly allocated to
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* non constant storage */
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strcpy((char *)trig->name, name);
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up_write(&triggers_list_lock);
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}
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EXPORT_SYMBOL_GPL(led_trigger_rename_static);
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/* LED Trigger Interface */
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int led_trigger_register(struct led_trigger *trig)
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{
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struct led_classdev *led_cdev;
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struct led_trigger *_trig;
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rwlock_init(&trig->leddev_list_lock);
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INIT_LIST_HEAD(&trig->led_cdevs);
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down_write(&triggers_list_lock);
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/* Make sure the trigger's name isn't already in use */
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list_for_each_entry(_trig, &trigger_list, next_trig) {
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if (!strcmp(_trig->name, trig->name) &&
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(trig->trigger_type == _trig->trigger_type ||
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!trig->trigger_type || !_trig->trigger_type)) {
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up_write(&triggers_list_lock);
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return -EEXIST;
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}
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}
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/* Add to the list of led triggers */
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list_add_tail(&trig->next_trig, &trigger_list);
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up_write(&triggers_list_lock);
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/* Register with any LEDs that have this as a default trigger */
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down_read(&leds_list_lock);
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list_for_each_entry(led_cdev, &leds_list, node) {
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down_write(&led_cdev->trigger_lock);
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if (!led_cdev->trigger && led_cdev->default_trigger &&
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!strcmp(led_cdev->default_trigger, trig->name) &&
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trigger_relevant(led_cdev, trig)) {
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led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
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led_trigger_set(led_cdev, trig);
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}
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up_write(&led_cdev->trigger_lock);
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}
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up_read(&leds_list_lock);
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return 0;
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}
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EXPORT_SYMBOL_GPL(led_trigger_register);
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void led_trigger_unregister(struct led_trigger *trig)
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{
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struct led_classdev *led_cdev;
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if (list_empty_careful(&trig->next_trig))
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return;
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/* Remove from the list of led triggers */
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down_write(&triggers_list_lock);
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list_del_init(&trig->next_trig);
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up_write(&triggers_list_lock);
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/* Remove anyone actively using this trigger */
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down_read(&leds_list_lock);
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list_for_each_entry(led_cdev, &leds_list, node) {
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down_write(&led_cdev->trigger_lock);
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if (led_cdev->trigger == trig)
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led_trigger_set(led_cdev, NULL);
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up_write(&led_cdev->trigger_lock);
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}
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up_read(&leds_list_lock);
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}
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EXPORT_SYMBOL_GPL(led_trigger_unregister);
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static void devm_led_trigger_release(struct device *dev, void *res)
|
|
{
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|
led_trigger_unregister(*(struct led_trigger **)res);
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|
}
|
|
|
|
int devm_led_trigger_register(struct device *dev,
|
|
struct led_trigger *trig)
|
|
{
|
|
struct led_trigger **dr;
|
|
int rc;
|
|
|
|
dr = devres_alloc(devm_led_trigger_release, sizeof(*dr),
|
|
GFP_KERNEL);
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|
if (!dr)
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|
return -ENOMEM;
|
|
|
|
*dr = trig;
|
|
|
|
rc = led_trigger_register(trig);
|
|
if (rc)
|
|
devres_free(dr);
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|
else
|
|
devres_add(dev, dr);
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|
|
|
return rc;
|
|
}
|
|
EXPORT_SYMBOL_GPL(devm_led_trigger_register);
|
|
|
|
/* Simple LED Trigger Interface */
|
|
|
|
void led_trigger_event(struct led_trigger *trig,
|
|
enum led_brightness brightness)
|
|
{
|
|
struct led_classdev *led_cdev;
|
|
unsigned long flags;
|
|
|
|
if (!trig)
|
|
return;
|
|
|
|
read_lock_irqsave(&trig->leddev_list_lock, flags);
|
|
list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list)
|
|
led_set_brightness(led_cdev, brightness);
|
|
read_unlock_irqrestore(&trig->leddev_list_lock, flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(led_trigger_event);
|
|
|
|
static void led_trigger_blink_setup(struct led_trigger *trig,
|
|
unsigned long *delay_on,
|
|
unsigned long *delay_off,
|
|
int oneshot,
|
|
int invert)
|
|
{
|
|
struct led_classdev *led_cdev;
|
|
unsigned long flags;
|
|
|
|
if (!trig)
|
|
return;
|
|
|
|
read_lock_irqsave(&trig->leddev_list_lock, flags);
|
|
list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list) {
|
|
if (oneshot)
|
|
led_blink_set_oneshot(led_cdev, delay_on, delay_off,
|
|
invert);
|
|
else
|
|
led_blink_set(led_cdev, delay_on, delay_off);
|
|
}
|
|
read_unlock_irqrestore(&trig->leddev_list_lock, flags);
|
|
}
|
|
|
|
void led_trigger_blink(struct led_trigger *trig,
|
|
unsigned long *delay_on,
|
|
unsigned long *delay_off)
|
|
{
|
|
led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
|
|
}
|
|
EXPORT_SYMBOL_GPL(led_trigger_blink);
|
|
|
|
void led_trigger_blink_oneshot(struct led_trigger *trig,
|
|
unsigned long *delay_on,
|
|
unsigned long *delay_off,
|
|
int invert)
|
|
{
|
|
led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
|
|
}
|
|
EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
|
|
|
|
void led_trigger_register_simple(const char *name, struct led_trigger **tp)
|
|
{
|
|
struct led_trigger *trig;
|
|
int err;
|
|
|
|
trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
|
|
|
|
if (trig) {
|
|
trig->name = name;
|
|
err = led_trigger_register(trig);
|
|
if (err < 0) {
|
|
kfree(trig);
|
|
trig = NULL;
|
|
pr_warn("LED trigger %s failed to register (%d)\n",
|
|
name, err);
|
|
}
|
|
} else {
|
|
pr_warn("LED trigger %s failed to register (no memory)\n",
|
|
name);
|
|
}
|
|
*tp = trig;
|
|
}
|
|
EXPORT_SYMBOL_GPL(led_trigger_register_simple);
|
|
|
|
void led_trigger_unregister_simple(struct led_trigger *trig)
|
|
{
|
|
if (trig)
|
|
led_trigger_unregister(trig);
|
|
kfree(trig);
|
|
}
|
|
EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
|