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

From	Ingo Molnar <mingo@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2] jump_label: reduce the size of struct static_key
Date	2017-01-20 08:30 +0100
Message-ID	<t1BO1-4ji-1@gated-at.bofh.it> (permalink)
References	<sVYNk-8qL-7@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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* Jason Baron <jbaron@akamai.com> 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

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Re: [PATCH v2] jump_label: reduce the size of struct static_key Ingo Molnar <mingo@kernel.org> - 2017-01-20 08:30 +0100
  Re: [PATCH v2] jump_label: reduce the size of struct static_key Jason Baron <jbaron@akamai.com> - 2017-01-20 21:10 +0100
    Re: [PATCH v2] jump_label: reduce the size of struct static_key Ingo Molnar <mingo@kernel.org> - 2017-01-21 08:10 +0100
      Re: [PATCH v2] jump_label: reduce the size of struct static_key Jason Baron <jbaron@akamai.com> - 2017-01-23 21:50 +0100

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