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Date: Tue, 22 Feb 2011 17:38:29 +0200
Message-ID: <AANLkTi=f+XMp0r77jbuq44uz9TfaOttm==JXdt-6RXrh@mail.gmail.com>
Subject: Re: [PATCH v2 1/1] headers: fix circular dependency between
 linux/sched.h and linux/wait.h
From: David Cohen <dacohen@gmail.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>, linux-kernel@vger.kernel.org,
        mingo@elte.hu, linux-omap@vger.kernel.org, linux-media@vger.kernel.org,
        Alexey Dobriyan <adobriyan@gmail.com>
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On Mon, Feb 21, 2011 at 7:27 PM, Oleg Nesterov <oleg@redhat.com> wrote:
> On 02/21, Oleg Nesterov wrote:
>>
>> On 02/21, Peter Zijlstra wrote:
>> >
>> > afaict its needed because struct signal_struct and struct sighand_struct
>> > include a wait_queue_head_t. The inclusion seems to come through
>> > completion.h, but afaict we don't actually need to include completion.h
>> > because all we have is a pointer to a completion, which is perfectly
>> > fine with an incomplete type.
>> >
>> > This all would suggest we move the signal bits into their own header
>> > (include/linux/signal.h already exists and seems inviting).
>>
>> Agreed, sched.h contatins a lot of garbage, including the signal bits.
>>
>> As for signal_struct in particular I am not really sure, it is just
>> misnamed. It is in fact "struct process" or "struct thread_group". But
>> dequeue_signal/etc should go into signal.h.
>>
>> The only problem, it is not clear how to test such a change.
>
> Ah. sched.h includes signal.h, the testing is not the problem.

If sched.h includes signal.h and we move wait_queue_head_t users to
signal.h, it means signal.h should include wait.h and then it is a
problem to include sched.h in wait.h.

>
> So, we can (at least) safely move some declarations.

Safely, yes, but it won't solve the issue for TASK_* in wait.h.

Br,

David

>
> Oleg.
>
>
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