On Mon, Sep 07, 2015 at 12:08:17PM +0530, Pranay Srivastava wrote:
> On Sun, Sep 6, 2015 at 11:18 PM, Clément Vuchener
> <clement.vuchener@xxxxxxxxx> wrote:
> > Hello,
> >
> > I am trying to write a driver that uses LED class devices using works for setting the LED brightness but I am not sure of how to unregister the devices.
> >
> > I have been using code like this:
> > led_classdev_unregister(&drvdata->backlight.cdev);
> > cancel_work_sync(&drvdata->backlight.work);
> > trying with both flush_work or cancel_work_sync as I have seen it in other drivers.
> >
> > Using flush_work, the kernel oops in my work function when I unplug the device. cancel_work_sync seems to fix that, but I am not sure it will work every time. I would like to understand what happens and if I am doing something wrong, to be sure it will not break in some different setup.
>
> Can you post the backtrace?
>
I could not get it with my patched kernel (I must be missing some config option) so I used the code as a module on my fedora 22 (4.1.6) kernel.
general protection fault: 0000 [#1] SMP
Modules linked in: hid_corsair_k90(OE) bnep bluetooth nf_nat_h323 nf_conntrack_h323 nf_nat_pptp nf_nat_proto_gre nf_conntrack_pptp nf_conntrack_proto_g
snd_hda_codec_hdmi coretemp arc4 kvm_intel snd_hda_codec_realtek iwldvm kvm snd_hda_codec_generic mac80211 snd_hda_intel snd_hda_controller snd_hda_co
CPU: 2 PID: 491 Comm: kworker/2:3 Tainted: G OE 4.1.6-200.fc22.x86_64 #1
Hardware name: CLEVO CO. W350ET/W350ET, BIOS 1.02.21PM v3 07/01/2013
Workqueue: events k90_record_led_work [hid_corsair_k90]
task: ffff880223bd4f00 ti: ffff8800c92a0000 task.ti: ffff8800c92a0000
RIP: 0010:[<ffffffff814e8816>] [<ffffffff814e8816>] __dev_printk+0x26/0x90
RSP: 0018:ffff8800c92a3d48 EFLAGS: 00010202
RAX: 657079740000009d RBX: ffff8801fcee7800 RCX: 000000000001a2e1
RDX: ffff8800c92a3d58 RSI: ffff8801fcee7800 RDI: ffffffff81a2673f
RBP: ffff8800c92a3d48 R08: 0000001400730102 R09: ffff8800c92a3d58
R10: ffffffff81578c4b R11: 0000000000000000 R12: ffff88022f317000
R13: ffff88022f31b900 R14: 0000000000000080 R15: ffff8801fcc7d320
FS: 0000000000000000(0000) GS:ffff88022f300000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000002eee850 CR3: 0000000002c0b000 CR4: 00000000001406e0
Stack:
ffff8800c92a3db8 ffffffff814e8bd2 ffffffffa09701f8 ffff8800c92a3d68
ffff880100000010 ffff8800c92a3dc8 ffff8800c92a3d88 000000002440e468
0000000000000000 ffff8801fcee7800 00000000ffffffed 000000000001a2e1
Call Trace:
[<ffffffff814e8bd2>] dev_warn+0x62/0x80
[<ffffffffa096f44c>] k90_record_led_work+0x8c/0xa0 [hid_corsair_k90]
[<ffffffff8179da31>] ? __schedule+0x241/0x720
[<ffffffff810baadb>] process_one_work+0x1bb/0x410
[<ffffffff810baeec>] worker_thread+0x1bc/0x480
[<ffffffff810bad30>] ? process_one_work+0x410/0x410
[<ffffffff810bad30>] ? process_one_work+0x410/0x410
[<ffffffff810c0bf8>] kthread+0xd8/0xf0
[<ffffffff810c0b20>] ? kthread_worker_fn+0x180/0x180
[<ffffffff817a2322>] ret_from_fork+0x42/0x70
[<ffffffff810c0b20>] ? kthread_worker_fn+0x180/0x180
Code: 00 00 00 00 00 0f 1f 44 00 00 55 48 85 f6 49 89 d1 48 89 e5 74 60 4c 8b 46 50 4d 85 c0 74 26 48 8b 86 90 00 00 00 48 85 c0 74 2a <48> 8b 08 0f be
RIP [<ffffffff814e8816>] __dev_printk+0x26/0x90
> >
> > Another problem I have with this unregistering is that the LED brightness is set to zero when unregistering when the hardware is supposed to remember the last settings. Thus the LED state is reset when detaching and reattaching the driver.
> >
> > Below is the full code from my driver, if you need it:
> >
> > /*
> > * HID driver for Corsair devices
> > *
> > * Supported devices:
> > * - Vengeance K90 Keyboard
> > *
> > * Copyright (c) 2015 Clement Vuchener
> > */
> >
> > /*
> > * This program is free software; you can redistribute it and/or modify it
> > * under the terms of the GNU General Public License as published by the Free
> > * Software Foundation; either version 2 of the License, or (at your option)
> > * any later version.
> > */
> >
> > #include <linux/hid.h>
> > #include <linux/module.h>
> > #include <linux/usb.h>
> > #include <linux/leds.h>
> >
> > #include "hid-ids.h"
> >
> > struct k90_led {
> > struct led_classdev cdev;
> > int brightness;
> > struct work_struct work;
> > };
> >
> > struct k90_drvdata {
> > int current_profile;
> > int macro_mode;
> > int meta_locked;
> > struct k90_led backlight;
> > struct k90_led record_led;
> > };
> >
> > #define K90_GKEY_COUNT 18
> >
> > static int k90_usage_to_gkey(unsigned int usage)
> > {
> > /* G1 (0xd0) to G16 (0xdf) */
> > if (usage >= 0xd0 && usage <= 0xdf)
> > return usage - 0xd0 + 1;
> > /* G17 (0xe8) to G18 (0xe9) */
> > if (usage >= 0xe8 && usage <= 0xe9)
> > return usage - 0xe8 + 17;
> > return 0;
> > }
> >
> > static unsigned short k90_gkey_map[K90_GKEY_COUNT] = {
> > BTN_TRIGGER_HAPPY1,
> > BTN_TRIGGER_HAPPY2,
> > BTN_TRIGGER_HAPPY3,
> > BTN_TRIGGER_HAPPY4,
> > BTN_TRIGGER_HAPPY5,
> > BTN_TRIGGER_HAPPY6,
> > BTN_TRIGGER_HAPPY7,
> > BTN_TRIGGER_HAPPY8,
> > BTN_TRIGGER_HAPPY9,
> > BTN_TRIGGER_HAPPY10,
> > BTN_TRIGGER_HAPPY11,
> > BTN_TRIGGER_HAPPY12,
> > BTN_TRIGGER_HAPPY13,
> > BTN_TRIGGER_HAPPY14,
> > BTN_TRIGGER_HAPPY15,
> > BTN_TRIGGER_HAPPY16,
> > BTN_TRIGGER_HAPPY17,
> > BTN_TRIGGER_HAPPY18,
> > };
> >
> > module_param_array_named(gkey_codes, k90_gkey_map, ushort, NULL, S_IRUGO);
> >
> > #define K90_USAGE_SPECIAL_MIN 0xf0
> > #define K90_USAGE_SPECIAL_MAX 0xff
> >
> > #define K90_USAGE_MACRO_RECORD_START 0xf6
> > #define K90_USAGE_MACRO_RECORD_STOP 0xf7
> >
> > #define K90_USAGE_PROFILE 0xf1
> > #define K90_USAGE_M1 0xf1
> > #define K90_USAGE_M2 0xf2
> > #define K90_USAGE_M3 0xf3
> > #define K90_USAGE_PROFILE_MAX 0xf3
> >
> > #define K90_USAGE_META_OFF 0xf4
> > #define K90_USAGE_META_ON 0xf5
> >
> > #define K90_USAGE_LIGHT 0xfa
> > #define K90_USAGE_LIGHT_OFF 0xfa
> > #define K90_USAGE_LIGHT_DIM 0xfb
> > #define K90_USAGE_LIGHT_MEDIUM 0xfc
> > #define K90_USAGE_LIGHT_BRIGHT 0xfd
> > #define K90_USAGE_LIGHT_MAX 0xfd
> >
> > /* USB control protocol */
> >
> > #define K90_REQUEST_BRIGHTNESS 49
> > #define K90_REQUEST_MACRO_MODE 2
> > #define K90_REQUEST_STATUS 4
> > #define K90_REQUEST_GET_MODE 5
> > #define K90_REQUEST_PROFILE 20
> >
> > #define K90_MACRO_MODE_SW 0x0030
> > #define K90_MACRO_MODE_HW 0x0001
> >
> > #define K90_MACRO_LED_ON 0x0020
> > #define K90_MACRO_LED_OFF 0x0040
> >
> > /*
> > * LED class devices
> > */
> >
> > #define K90_BACKLIGHT_LED_SUFFIX ":blue:backlight"
> > #define K90_RECORD_LED_SUFFIX ":red:record"
> >
> > static enum led_brightness k90_brightness_get(struct led_classdev *led_cdev)
> > {
> > struct k90_led *led = container_of(led_cdev, struct k90_led, cdev);
> >
> > return led->brightness;
> > }
> >
> > static void k90_brightness_set(struct led_classdev *led_cdev,
> > enum led_brightness brightness)
> > {
> > struct k90_led *led = container_of(led_cdev, struct k90_led, cdev);
> >
> > led->brightness = brightness;
> > schedule_work(&led->work);
> > }
> >
> > static void k90_backlight_work(struct work_struct *work)
> > {
> > int ret;
> > struct k90_led *led = container_of(work, struct k90_led, work);
> > struct device *dev = led->cdev.dev->parent;
> > struct usb_interface *usbif = to_usb_interface(dev->parent);
> > struct usb_device *usbdev = interface_to_usbdev(usbif);
> >
> > ret = usb_control_msg(usbdev, usb_sndctrlpipe(usbdev, 0),
> > K90_REQUEST_BRIGHTNESS,
> > USB_DIR_OUT | USB_TYPE_VENDOR |
> > USB_RECIP_DEVICE, led->brightness, 0,
> > NULL, 0, USB_CTRL_SET_TIMEOUT);
> > if (ret != 0)
> > dev_warn(dev, "Failed to set backlight brightness (error: %d).\n",
> > ret);
> > }
> >
> > static void k90_record_led_work(struct work_struct *work)
> > {
> > int ret;
> > struct k90_led *led = container_of(work, struct k90_led, work);
> > struct device *dev = led->cdev.dev->parent;
> > struct usb_interface *usbif = to_usb_interface(dev->parent);
> > struct usb_device *usbdev = interface_to_usbdev(usbif);
> > int value;
> >
> > if (led->brightness > 0)
> > value = K90_MACRO_LED_ON;
> > else
> > value = K90_MACRO_LED_OFF;
> >
> > ret = usb_control_msg(usbdev, usb_sndctrlpipe(usbdev, 0),
> > K90_REQUEST_MACRO_MODE,
> > USB_DIR_OUT | USB_TYPE_VENDOR |
> > USB_RECIP_DEVICE, value, 0, NULL, 0,
> > USB_CTRL_SET_TIMEOUT);
> > if (ret != 0)
> > dev_warn(dev, "Failed to set record LED state (error: %d).\n",
> > ret);
> > }
> >
> > /*
> > * Keyboard attributes
> > */
> >
> > static ssize_t k90_show_macro_mode(struct device *dev,
> > struct device_attribute *attr, char *buf)
> > {
> > struct k90_drvdata *drvdata = dev_get_drvdata(dev);
> >
> > return snprintf(buf, PAGE_SIZE, "%s\n",
> > (drvdata->macro_mode ? "HW" : "SW"));
> > }
> >
> > static ssize_t k90_store_macro_mode(struct device *dev,
> > struct device_attribute *attr,
> > const char *buf, size_t count)
> > {
> > int ret;
> > struct usb_interface *usbif = to_usb_interface(dev->parent);
> > struct usb_device *usbdev = interface_to_usbdev(usbif);
> > struct k90_drvdata *drvdata = dev_get_drvdata(dev);
> > __u16 value;
> >
> > if (strncmp(buf, "SW", 2) == 0)
> > value = K90_MACRO_MODE_SW;
> > else if (strncmp(buf, "HW", 2) == 0)
> > value = K90_MACRO_MODE_HW;
> > else
> > return -EINVAL;
> >
> > ret = usb_control_msg(usbdev, usb_sndctrlpipe(usbdev, 0),
> > K90_REQUEST_MACRO_MODE,
> > USB_DIR_OUT | USB_TYPE_VENDOR |
> > USB_RECIP_DEVICE, value, 0, NULL, 0,
> > USB_CTRL_SET_TIMEOUT);
> > if (ret != 0)
> > return ret;
> >
> > drvdata->macro_mode = (value == K90_MACRO_MODE_HW);
> >
> > return count;
> > }
> >
> > static ssize_t k90_show_current_profile(struct device *dev,
> > struct device_attribute *attr,
> > char *buf)
> > {
> > struct k90_drvdata *drvdata = dev_get_drvdata(dev);
> >
> > return snprintf(buf, PAGE_SIZE, "%d\n", drvdata->current_profile);
> > }
> >
> > static ssize_t k90_store_current_profile(struct device *dev,
> > struct device_attribute *attr,
> > const char *buf, size_t count)
> > {
> > int ret;
> > struct usb_interface *usbif = to_usb_interface(dev->parent);
> > struct usb_device *usbdev = interface_to_usbdev(usbif);
> > struct k90_drvdata *drvdata = dev_get_drvdata(dev);
> > int profile;
> >
> > if (kstrtoint(buf, 10, &profile))
> > return -EINVAL;
> > if (profile < 1 || profile > 3)
> > return -EINVAL;
> >
> > ret = usb_control_msg(usbdev, usb_sndctrlpipe(usbdev, 0),
> > K90_REQUEST_PROFILE,
> > USB_DIR_OUT | USB_TYPE_VENDOR |
> > USB_RECIP_DEVICE, profile, 0, NULL, 0,
> > USB_CTRL_SET_TIMEOUT);
> > if (ret != 0)
> > return ret;
> >
> > drvdata->current_profile = profile;
> >
> > return count;
> > }
> >
> > static DEVICE_ATTR(macro_mode, 0644, k90_show_macro_mode, k90_store_macro_mode);
> > static DEVICE_ATTR(current_profile, 0644, k90_show_current_profile,
> > k90_store_current_profile);
> >
> > static struct attribute *k90_attrs[] = {
> > &dev_attr_macro_mode.attr,
> > &dev_attr_current_profile.attr,
> > NULL
> > };
> >
> > static const struct attribute_group k90_attr_group = {
> > .attrs = k90_attrs,
> > };
> >
> > /*
> > * Driver functions
> > */
> >
> > static int k90_init_special_functions(struct hid_device *dev)
> > {
> > int ret;
> > struct usb_interface *usbif = to_usb_interface(dev->dev.parent);
> > struct usb_device *usbdev = interface_to_usbdev(usbif);
> > char data[8];
> > struct k90_drvdata *drvdata =
> > kzalloc(sizeof(struct k90_drvdata), GFP_KERNEL);
> > size_t name_sz;
> > char *name;
> > struct k90_led *led;
> >
> > if (!drvdata) {
> > ret = -ENOMEM;
> > goto fail_drvdata;
> > }
> > hid_set_drvdata(dev, drvdata);
> >
> > /* Get current status */
> > ret = usb_control_msg(usbdev, usb_rcvctrlpipe(usbdev, 0),
> > K90_REQUEST_STATUS,
> > USB_DIR_IN | USB_TYPE_VENDOR |
> > USB_RECIP_DEVICE, 0, 0, data, 8,
> > USB_CTRL_SET_TIMEOUT);
> > if (ret < 0) {
> > hid_warn(dev, "Failed to get K90 initial state (error %d).\n",
> > ret);
> > drvdata->backlight.brightness = 0;
> > drvdata->current_profile = 1;
> > } else {
> > drvdata->backlight.brightness = data[4];
> > drvdata->current_profile = data[7];
> > }
> > /* Get current mode */
> > ret = usb_control_msg(usbdev, usb_rcvctrlpipe(usbdev, 0),
> > K90_REQUEST_GET_MODE,
> > USB_DIR_IN | USB_TYPE_VENDOR |
> > USB_RECIP_DEVICE, 0, 0, data, 2,
> > USB_CTRL_SET_TIMEOUT);
> > if (ret < 0)
> > hid_warn(dev, "Failed to get K90 initial mode (error %d).\n",
> > ret);
> > else {
> > switch (data[0]) {
> > case K90_MACRO_MODE_HW:
> > drvdata->macro_mode = 1;
> > break;
> > case K90_MACRO_MODE_SW:
> > drvdata->macro_mode = 0;
> > break;
> > default:
> > hid_warn(dev, "K90 in unknown mode: %02x.\n",
> > data[0]);
> > }
> > }
> >
> > /* Init LED device for backlight */
> > name_sz =
> > strlen(dev_name(&dev->dev)) + sizeof(K90_BACKLIGHT_LED_SUFFIX);
> > name = devm_kzalloc(&dev->dev, name_sz, GFP_KERNEL);
> > if (!name) {
> > ret = -ENOMEM;
> > goto fail_backlight;
> > }
> > snprintf(name, name_sz, "%s" K90_BACKLIGHT_LED_SUFFIX,
> > dev_name(&dev->dev));
> > led = &drvdata->backlight;
> > led->cdev.name = name;
> > led->cdev.max_brightness = 3;
> > led->cdev.brightness_set = k90_brightness_set;
> > led->cdev.brightness_get = k90_brightness_get;
> > INIT_WORK(&led->work, k90_backlight_work);
> > ret = led_classdev_register(&dev->dev, &led->cdev);
> > if (ret != 0)
> > goto fail_backlight;
> >
> > /* Init LED device for record LED */
> > name_sz = strlen(dev_name(&dev->dev)) + sizeof(K90_RECORD_LED_SUFFIX);
> > name = devm_kzalloc(&dev->dev, name_sz, GFP_KERNEL);
> > if (!name) {
> > ret = -ENOMEM;
> > goto fail_record_led;
> > }
> > snprintf(name, name_sz, "%s" K90_RECORD_LED_SUFFIX,
> > dev_name(&dev->dev));
> > led = &drvdata->record_led;
> > led->cdev.name = name;
> > led->cdev.max_brightness = 1;
> > led->cdev.brightness_set = k90_brightness_set;
> > led->cdev.brightness_get = k90_brightness_get;
> > INIT_WORK(&led->work, k90_record_led_work);
> > ret = led_classdev_register(&dev->dev, &led->cdev);
> > if (ret != 0)
> > goto fail_record_led;
> >
> > /* Init attributes */
> > ret = sysfs_create_group(&dev->dev.kobj, &k90_attr_group);
> > if (ret != 0)
> > goto fail_sysfs;
> >
> > return 0;
> >
> > fail_sysfs:
> > led_classdev_unregister(&drvdata->record_led.cdev);
> > cancel_work_sync(&drvdata->record_led.work);
> > fail_record_led:
> > led_classdev_unregister(&drvdata->backlight.cdev);
> > cancel_work_sync(&drvdata->backlight.work);
> > fail_backlight:
> > kfree(drvdata);
> > fail_drvdata:
> > hid_set_drvdata(dev, NULL);
> > return ret;
> > }
> >
> > static void k90_cleanup_special_functions(struct hid_device *dev)
> > {
> > struct k90_drvdata *drvdata = hid_get_drvdata(dev);
> >
> > if (drvdata) {
> > sysfs_remove_group(&dev->dev.kobj, &k90_attr_group);
> > led_classdev_unregister(&drvdata->record_led.cdev);
> > led_classdev_unregister(&drvdata->backlight.cdev);
>
> flush_work/cancel_work before doing unregistering?
>
If led_classdev_unregister generates work (setting the brightness to zero), there will still be work in the workqueue after the cleanup. I don't understand why the work should be flushed/cancelled while the led device is still active.
> > cancel_work_sync(&drvdata->record_led.work);
> > cancel_work_sync(&drvdata->backlight.work);
> > kfree(drvdata);
> > }
> > }
> >
> > static int k90_probe(struct hid_device *dev, const struct hid_device_id *id)
> > {
> > int ret;
> > struct usb_interface *usbif = to_usb_interface(dev->dev.parent);
> >
> > ret = hid_parse(dev);
> > if (ret != 0) {
> > hid_err(dev, "parse failed\n");
> > return ret;
> > }
> > ret = hid_hw_start(dev, HID_CONNECT_DEFAULT);
> > if (ret != 0) {
> > hid_err(dev, "hw start failed\n");
> > return ret;
> > }
> >
> > if (usbif->cur_altsetting->desc.bInterfaceNumber == 0) {
> > ret = k90_init_special_functions(dev);
> > if (ret != 0)
> > hid_warn(dev, "Failed to initialize K90 special functions.\n");
> > } else
> > hid_set_drvdata(dev, NULL);
> >
> > return 0;
> > }
> >
> > static void k90_remove(struct hid_device *dev)
> > {
> > struct usb_interface *usbif = to_usb_interface(dev->dev.parent);
> >
> > if (usbif->cur_altsetting->desc.bInterfaceNumber == 0)
> > k90_cleanup_special_functions(dev);
> >
> > hid_hw_stop(dev);
> > }
> >
> > static int k90_event(struct hid_device *dev, struct hid_field *field,
> > struct hid_usage *usage, __s32 value)
> > {
> > struct k90_drvdata *drvdata = hid_get_drvdata(dev);
> >
> > if (!drvdata)
> > return 0;
> >
> > switch (usage->hid & HID_USAGE) {
> > case K90_USAGE_MACRO_RECORD_START:
> > drvdata->record_led.brightness = 1;
> > break;
> > case K90_USAGE_MACRO_RECORD_STOP:
> > drvdata->record_led.brightness = 0;
> > break;
> > case K90_USAGE_M1:
> > case K90_USAGE_M2:
> > case K90_USAGE_M3:
> > drvdata->current_profile =
> > (usage->hid & HID_USAGE) - K90_USAGE_PROFILE + 1;
> > break;
> > case K90_USAGE_META_OFF:
> > drvdata->meta_locked = 0;
> > break;
> > case K90_USAGE_META_ON:
> > drvdata->meta_locked = 1;
> > break;
> > case K90_USAGE_LIGHT_OFF:
> > case K90_USAGE_LIGHT_DIM:
> > case K90_USAGE_LIGHT_MEDIUM:
> > case K90_USAGE_LIGHT_BRIGHT:
> > drvdata->backlight.brightness = (usage->hid & HID_USAGE) -
> > K90_USAGE_LIGHT;
> > break;
> > default:
> > break;
> > }
> >
> > return 0;
> > }
> >
> > static int k90_input_mapping(struct hid_device *dev, struct hid_input *input,
> > struct hid_field *field, struct hid_usage *usage,
> > unsigned long **bit, int *max)
> > {
> > int gkey;
> >
> > gkey = k90_usage_to_gkey(usage->hid & HID_USAGE);
> > if (gkey != 0) {
> > hid_map_usage_clear(input, usage, bit, max, EV_KEY,
> > k90_gkey_map[gkey - 1]);
> > return 1;
> > }
> > if ((usage->hid & HID_USAGE) >= K90_USAGE_SPECIAL_MIN &&
> > (usage->hid & HID_USAGE) <= K90_USAGE_SPECIAL_MAX)
> > return -1;
> >
> > return 0;
> > }
> >
> > static const struct hid_device_id k90_devices[] = {
> > { HID_USB_DEVICE(USB_VENDOR_ID_CORSAIR, USB_DEVICE_ID_CORSAIR_K90) },
> > {}
> > };
> >
> > MODULE_DEVICE_TABLE(hid, k90_devices);
> >
> > static struct hid_driver k90_driver = {
> > .name = "k90",
> > .id_table = k90_devices,
> > .probe = k90_probe,
> > .event = k90_event,
> > .remove = k90_remove,
> > .input_mapping = k90_input_mapping,
> > };
> >
> > static int __init k90_init(void)
> > {
> > return hid_register_driver(&k90_driver);
> > }
> >
> > static void k90_exit(void)
> > {
> > hid_unregister_driver(&k90_driver);
> > }
> >
> > module_init(k90_init);
> > module_exit(k90_exit);
> >
> > MODULE_LICENSE("GPL");
> > MODULE_AUTHOR("Clement Vuchener");
> > MODULE_DESCRIPTION("HID driver for Corsair Vengeance K90 Keyboard");
> >
> > _______________________________________________
> > Kernelnewbies mailing list
> > Kernelnewbies@xxxxxxxxxxxxxxxxx
> > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>
>
>
> --
> ---P.K.S
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