Re: [PATCH v3 3/4] block: add support for notifications

[Jens Axboe <axboe@kernel.dk>]

On 6/25/24 8:51 PM, Daniel Golle wrote:
> +static int blk_call_notifier_add(struct device *dev)
> +{
> +	struct blk_device_list *new_blkdev;
> +
> +	new_blkdev = kmalloc(sizeof(*new_blkdev), GFP_KERNEL);
> +	if (!new_blkdev)
> +		return -ENOMEM;
> +
> +	new_blkdev->dev = dev;
> +	mutex_lock(&blk_notifier_lock);
> +	list_add_tail(&new_blkdev->list, &blk_devices);
> +	raw_notifier_call_chain(&blk_notifier_list, BLK_DEVICE_ADD, dev);
> +	mutex_unlock(&blk_notifier_lock);
> +
> +	return 0;
> +}

Nit: redundant newline.

> +device_initcall(blk_notifications_init);
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index b2f1362c4681..8d22ba03e3e1 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -1687,4 +1687,12 @@ static inline bool bdev_can_atomic_write(struct block_device *bdev)
>  
>  #define DEFINE_IO_COMP_BATCH(name)	struct io_comp_batch name = { }
>  
> +
> +#ifdef CONFIG_BLOCK_NOTIFIERS

#if defined(CONFIG_BLOCK_NOTIFIERS)

> +#define BLK_DEVICE_ADD		1
> +#define BLK_DEVICE_REMOVE	2
> +void blk_register_notify(struct notifier_block *nb);
> +void blk_unregister_notify(struct notifier_block *nb);
> +#endif

Surely these helpers should have a !CONFIG_BLOCK_NOTIFIERS failure case
definition? Either that, or dummies. As it stands, any caller would need
to check if it's enabled or not.

-- 
Jens Axboe