linux-kernel - Re: linux/kernel/sched.c: context

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Message-Id: <201009081523.41718.fabio@metanix.org>
Date:	Wed, 8 Sep 2010 15:23:40 +0200
From:	fabio de francesco <fabio@...anix.org>
To:	LKML <linux-kernel@...r.kernel.org>
Subject: Re: linux/kernel/sched.c: context_switch().

On Wednesday 08 September 2010 15:10:49 you wrote:
> Long day? Do you mean likely(!mm) actually means unlikely(0)?

No, no. I am sorry for my poor English. I mean:"likely(!mm)" is like 
"likely(0)".
 
> On 8 September 2010 20:08, fabio de francesco <fabio@...anix.org> wrote:
> > There must be something I am missing in sched.c at context_switch()
> > function definition.
> > 
> > There I can read the following code:
> > 
> > static inline void
> > context_switch(struct rq *rq, struct task_struct *prev,
> >               struct task_struct *next)
> > {
> >        ...
> >        struct mm_struct *mm;
> >        mm = next->mm;
> >        if (likely(!mm)) {
> >                next->active_mm = oldmm;
> >                atomic_inc(&oldmm->mm_count);
> >                enter_lazy_tlb(oldmm, next);
> >        } else
> >                switch_mm(oldmm, mm, next);
> >        ...
> > }
> > 
> > May someone please explain why the mm pointer is likely supposed to be
> > NULL?
> > 
> > Thanks in advance.
> > 
> > fabio
> > --
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