linux-kernel - Re: [PATCH] Use the tsk argument in init_new

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Message-ID: <20070721010014.GA5503@motherbox.xtechq.com.ar>
Date:	Fri, 20 Jul 2007 22:00:15 -0300
From:	Diego Woitasen <diegows@...ux.org.ar>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Diego Woitasen <diego@...tasen.com.ar>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Use the tsk argument in init_new_context()

On Thu, Jul 19, 2007 at 05:42:38PM -0700, Andrew Morton wrote:
> On Sun,  8 Jul 2007 22:55:08 -0300
> Diego Woitasen <diego@...tasen.com.ar> wrote:
> 
> > Signed-off-by: Diego Woitasen <diego@...tasen.com.ar>
> > ---
> >  arch/i386/kernel/ldt.c   |    2 +-
> >  arch/x86_64/kernel/ldt.c |    2 +-
> >  2 files changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/arch/i386/kernel/ldt.c b/arch/i386/kernel/ldt.c
> > index e0b2d17..c2eb4fb 100644
> > --- a/arch/i386/kernel/ldt.c
> > +++ b/arch/i386/kernel/ldt.c
> > @@ -96,7 +96,7 @@ int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
> >  
> >  	init_MUTEX(&mm->context.sem);
> >  	mm->context.size = 0;
> > -	old_mm = current->mm;
> > +	old_mm = tsk->mm;
> >  	if (old_mm && old_mm->context.size > 0) {
> >  		down(&old_mm->context.sem);
> >  		retval = copy_ldt(&mm->context, &old_mm->context);
> > diff --git a/arch/x86_64/kernel/ldt.c b/arch/x86_64/kernel/ldt.c
> > index bc9ffd5..99a92ed 100644
> > --- a/arch/x86_64/kernel/ldt.c
> > +++ b/arch/x86_64/kernel/ldt.c
> > @@ -100,7 +100,7 @@ int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
> >  
> >  	init_MUTEX(&mm->context.sem);
> >  	mm->context.size = 0;
> > -	old_mm = current->mm;
> > +	old_mm = tsk->mm;
> >  	if (old_mm && old_mm->context.size > 0) {
> >  		down(&old_mm->context.sem);
> >  		retval = copy_ldt(&mm->context, &old_mm->context);
> 
> 
> When called from dup_mm(), `tsk' refers to the new task and `current'
> refers to the old one.  I'd have expected this to crash during your testing?
> -
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Yes, sorry... that patch is bad. Now my question is, why all
architectures have the task argument and neither use it? I undertand now
that init_new_context() work with current but what about the *tsk arg.



-- 

--------------
Diego Woitasen
-
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