Re: [PATCH v2] jump_label: reduce the size of struct static_key

From: Ingo Molnar
Date: Fri Jan 20 2017 - 02:20:15 EST



* Jason Baron <jbaron@xxxxxxxxxx> wrote:

> struct static_key {
> atomic_t enabled;
> +/*
> + * bit 0 => 1 if key is initially true
> + * 0 if initially false
> + * bit 1 => 1 if points to struct static_key_mod
> + * 0 if points to struct jump_entry
> + */
> + union {
> + unsigned long type;
> + struct jump_entry *entries;
> + struct static_key_mod *next;
> + };


> + key->type = (unsigned long)jlm2 | static_key_type(key);

> + key->type = (unsigned long)jlm | static_key_type(key);

> + *prev = (struct static_key_mod *)((unsigned long)jlm->next |
> + ((unsigned long)*prev & JUMP_TYPE_MASK));

> + key->type = (unsigned long)jlm->entries |
> + static_key_type(key);

I really hate these very ugly type conversions. Is there no cleaner way?

For example the last line could sure be written as:

key->entries = jlm->entries;
key->type |= static_key_type(key);

right?

Thanks,

Ingo