The patch "usb: simplify usbport trigger" together with "leds: triggers: add device attribute support" caused an regression for the usbport trigger. it will no longer enumerate any active usb hub ports under the "ports" directory in the sysfs class directory, if the usb host drivers are fully initialized before the usbport trigger was loaded.
The reason is that the usbport driver tries to register the sysfs entries during the activate() callback. And this will fail with -2 / ENOENT because the patch "leds: triggers: add device attribute support" made it so that the sysfs "ports" group was only being added after the activate() callback succeeded. This version of the patch moves the device_add_groups() in front of the call to the trigger's activate() function in order to solve the problem. Cc: Greg Kroah-Hartman <[email protected]> Cc: Uwe Kleine-König <[email protected]> Cc: Rafał Miłecki <[email protected]> Fixes: 6f7b0bad8839 ("usb: simplify usbport trigger") Signed-off-by: Christian Lamparter <[email protected]> --- This version of the patch ... of which will be many more?! yeah, device_add_groups() in front of activate() works for the usbport driver since it dynamically registers the entries in "ports". However, if a trigger has a static list of entities this can get more complicated, since I think the sysfs entries will now be available before the activate() call even started and this can end up badly. So, is there any better approach? Introduce a "post_activate()" callback? Or use the event system and make usbport trigger on the KOBJ_CHANGE? use a (delayed) work_struct in usbport to register the ports at a slightly later time? etc... (Note: I'm hitting this on 4.19 too, so whatever the real fix will look like it should be backported) --- drivers/leds/led-triggers.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c index 17d73db1456e..08e7c724a9dc 100644 --- a/drivers/leds/led-triggers.c +++ b/drivers/leds/led-triggers.c @@ -134,6 +134,12 @@ int led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig) led_set_brightness(led_cdev, LED_OFF); } if (trig) { + ret = device_add_groups(led_cdev->dev, trig->groups); + if (ret) { + dev_err(led_cdev->dev, "Failed to add trigger attributes\n"); + goto err_add_groups; + } + write_lock_irqsave(&trig->leddev_list_lock, flags); list_add_tail(&led_cdev->trig_list, &trig->led_cdevs); write_unlock_irqrestore(&trig->leddev_list_lock, flags); @@ -146,12 +152,6 @@ int led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig) if (ret) goto err_activate; - - ret = device_add_groups(led_cdev->dev, trig->groups); - if (ret) { - dev_err(led_cdev->dev, "Failed to add trigger attributes\n"); - goto err_add_groups; - } } if (event) { @@ -165,17 +165,18 @@ int led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig) return 0; -err_add_groups: - +err_activate: + device_remove_groups(led_cdev->dev, trig->groups); if (trig->deactivate) trig->deactivate(led_cdev); -err_activate: led_cdev->trigger = NULL; led_cdev->trigger_data = NULL; write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags); list_del(&led_cdev->trig_list); write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock, flags); + +err_add_groups: led_set_brightness(led_cdev, LED_OFF); return ret; -- 2.20.1
