Re: [PATCH v7 1/3] cgroups: read-write lock CLONE_THREAD forking per threadgroup

From: Paul Menage
Date: Mon Feb 14 2011 - 00:32:19 EST


On Mon, Jan 24, 2011 at 1:05 PM, Andrew Morton
<akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> Risky. sched.h doesn't include rwsem.h.
>
> We could make it do so, but almost every compilation unit in the kernel
> includes sched.h.  It would be nicer to make the kernel build
> finer-grained, rather than blunter-grained.  Don't be afraid to add new
> header files if that is one way of doing this!
>

The only header files included by rwsem.h that aren't directly
included in sched.h already are linux/linkage.h and asm/atomic.h.
Since sighand_struct in sched.h has an atomic_t field, sched.h is
clearly including atomic.h somewhere indirectly. And there are mutex
fields in sched.h, which means it's indirectly including
linux/mutex.h, which includes linux/linkage.h. So I think that it's
hard to argue that this change would make the kernel build any more
heavyweight.

Paul
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