Re: Allow setting of number of raw devices as a module parameter

[Andrew Morton <akpm@linux-foundation.org>]

On Fri, 29 Apr 2011 00:24:29 +0200
Jan Kara <jack@suse.cz> wrote:

> Allow setting of maximal number of raw devices as a module parameter. This
> requires changing of static array into a vmalloced one (the array is going to
> be too large for kmalloc).
> 

Changelog failed to describe why the patch is needed.  Lacking that
information, we have no reason to apply it.

> +static int max_raw_minors = MAX_RAW_MINORS;

I suppose we could remove MAX_RAW_MINORS and use CONFIG_MAX_RAW_DEVS
directly.

> +
> +module_param(max_raw_minors, int, 0);
> +MODULE_PARM_DESC(max_raw_minors, "Maximum number of raw devices (1-65536)");
> +
>  /*
>   * Open/close code for raw IO.
>   *
> @@ -131,7 +137,7 @@ static int bind_set(int number, u64 majo
>  	struct raw_device_data *rawdev;
>  	int err = 0;
>  
> -	if (number <= 0 || number >= MAX_RAW_MINORS)
> +	if (number <= 0 || number >= max_raw_minors)
>  		return -EINVAL;
>  
>  	if (MAJOR(dev) != major || MINOR(dev) != minor)
> @@ -318,12 +324,26 @@ static int __init raw_init(void)
>  	dev_t dev = MKDEV(RAW_MAJOR, 0);
>  	int ret;
>  
> -	ret = register_chrdev_region(dev, MAX_RAW_MINORS, "raw");
> +	if (max_raw_minors < 1 || max_raw_minors > 65536) {
> +		printk(KERN_WARNING "raw: invalid max_raw_minors (must be"
> +			" between 1 and 65536), using %d\n", MAX_RAW_MINORS);
> +		max_raw_minors = MAX_RAW_MINORS;
> +	}
> +
> +	raw_devices = vmalloc(sizeof(struct raw_device_data) * max_raw_minors);
> +	if (!raw_devices) {
> +		printk(KERN_ERR "Not enough memory for raw device structures\n");
> +		ret = -ENOMEM;
> +		goto error;
> +	}
> +	memset(raw_devices, 0, sizeof(struct raw_device_data) * max_raw_minors);

vzalloc().