On Thu, Sep 09, 2021 at 05:25:08PM -0500, Ian Pilcher wrote:
> Allocate per-LED data structure and initialize with default values
>
> Create /sys/class/leds/<led>/block_devices directory
>
> Increment module reference count. Module can only be removed when no LEDs
> are associated with the trigger.
>
> Signed-off-by: Ian Pilcher <arequipeno@xxxxxxxxx>
> ---
> drivers/leds/trigger/ledtrig-blkdev.c | 57 +++++++++++++++++++++++++++
> 1 file changed, 57 insertions(+)
>
> diff --git a/drivers/leds/trigger/ledtrig-blkdev.c b/drivers/leds/trigger/ledtrig-blkdev.c
> index 40dc55e5d4f3..6f78a9515976 100644
> --- a/drivers/leds/trigger/ledtrig-blkdev.c
> +++ b/drivers/leds/trigger/ledtrig-blkdev.c
> @@ -164,6 +164,62 @@ static void blkdev_process(struct work_struct *const work)
> }
>
>
> +/*
> + *
> + * Associate an LED with the blkdev trigger
> + *
> + */
> +
> +static int blkdev_activate(struct led_classdev *const led_dev)
> +{
> + struct ledtrig_blkdev_led *led;
> + int ret;
> +
> + /* Don't allow module to be removed while any LEDs are linked */
> + if (WARN_ON(!try_module_get(THIS_MODULE))) {
That pattern is racy and broken and never ever ever add it to the kernel
again please. All existing in-kernel users of it are also wrong, we
have been removing them for decades now.
> + ret = -ENODEV; /* Shouldn't ever happen */
> + goto exit_return;
> + }
> +
> + led = kmalloc(sizeof(*led), GFP_KERNEL);
> + if (led == NULL) {
> + ret = -ENOMEM;
> + goto exit_put_module;
> + }
> +
> + led->led_dev = led_dev;
> + led->blink_msec = LEDTRIG_BLKDEV_BLINK_MSEC;
> + led->mode = LEDTRIG_BLKDEV_MODE_RW;
> + INIT_HLIST_HEAD(&led->disks);
> +
> + ret = mutex_lock_interruptible(&ledtrig_blkdev_mutex);
> + if (ret != 0)
> + goto exit_free;
> +
> + led->dir = kobject_create_and_add("linked_devices",
> + &led_dev->dev->kobj);
You have created a "raw" kobject in the device tree now, which means
that userspace will not be notified of it and will have a "hole" in it's
knowledge. Why not just create a named attribute group to this device
instead?
> + if (led->dir == NULL) {
> + ret = -ENOMEM;
> + goto exit_unlock;
> + }
> +
> + hlist_add_head(&led->leds_node, &ledtrig_blkdev_leds);
> + led_set_trigger_data(led_dev, led);
> + ret = 0;
> +
> +exit_unlock:
> + mutex_unlock(&ledtrig_blkdev_mutex);
> +exit_free:
> + if (ret != 0)
> + kfree(led);
> +exit_put_module:
> + if (ret != 0)
> + module_put(THIS_MODULE);
Again, racy and broken, please do not do this.
thanks,
greg k-h
