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    SubjectRe: [PATCH] Break out types from <linux/list.h> to <linux/list_types.h>.
    On 7/2/2010 4:48 PM, Matthew Wilcox wrote:
    > On Fri, Jul 02, 2010 at 03:33:52PM -0400, Chris Metcalf wrote:
    >> On 7/2/2010 3:19 PM, Matthew Wilcox wrote:
    >>> Why a new header file instead of linux/types.h?
    >> I was working from analogy to kvm_types.h, mm_types.h, rwlock_types.h,
    >> spinlock_types.h. My impression is that linux/types.h is generally for
    >> basic (non-struct) types, with atomic_t/atomic64_t being added as
    >> "almost non-struct types", and of course the historical exception of
    >> "struct ustat", which has been there since the dawn of time (0.97 anyway).
    > I think list_head, hlist_head and hlist_node qualify as "almost non-struct
    > types", don't you? :-)

    I see the smiley, but to reply seriously, the distinction I was making
    was that atomic_t is really just an integer type, but with typing magic
    to protect it from implicit conversion -- unlike list_head, which really
    is a more complex type.

    I suppose one could make a kind of "intent of the founders"
    constitutional law-type argument suggesting that the presence of "struct
    ustat" suggests more complex types are in fact appropriate in
    <linux/types.h>. :-)

    > I wouldn't mind seeing kvm_types.h, rwlock_types.h and spinlock_types.h
    > merged into types.h, personally. They're all pretty fundamental kernel
    > kind of types. It's a matter of taste, and I'm not particularly fussed
    > one way or the other.

    Somehow it's hard to see kvm_ioapic_redirect_entry on a par with size_t :-)

    > I just object to the unnecessary creation of tiny files like this.
    > Which is how we ended up with atomic_t and atomic64_t in there in the
    > first place :-)

    In any case, I think this either way is plausible, but in the absence of
    more folks weighing in, I think "avoid adding a complex type to
    <linux/types.h>" sounds more convincing to me than "avoid adding a new
    tiny file", though I certainly do buy the latter argument.

    Chris Metcalf, Tilera Corp.

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