linux-kernel - Re: [RFC PATCH v3 4/7] powerpc: regain entire stack space

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Message-ID: <20181003163024.281254bf@roar.ozlabs.ibm.com>
Date:   Wed, 3 Oct 2018 16:30:24 +1000
From:   Nicholas Piggin <npiggin@...il.com>
To:     Christophe LEROY <christophe.leroy@....fr>
Cc:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        aneesh.kumar@...ux.vnet.ibm.com, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [RFC PATCH v3 4/7] powerpc: regain entire stack space

On Wed, 3 Oct 2018 07:52:59 +0200
Christophe LEROY <christophe.leroy@....fr> wrote:

> Le 03/10/2018 à 07:34, Nicholas Piggin a écrit :
> > On Mon,  1 Oct 2018 12:30:25 +0000 (UTC)
> > Christophe Leroy <christophe.leroy@....fr> wrote:
> >   
> >> thread_info is not anymore in the stack, so the entire stack
> >> can now be used.  
> > 
> > Nice.
> >   
> >>
> >> In the meantime, all pointers to the stacks are not anymore
> >> pointers to thread_info so this patch changes them to void*  
> > 
> > Wasn't this previously effectively already the case with patch
> > 3/7? You had thread_info sized space left there, but it was not
> > used or initialized right? Does it make sense to move this part
> > of it to the previous patch?  
> 
> Not really.
> 
> In 3/7 I changed the prototypes of two functions that really used the 
> pointer as a task pointer only.
> 
> Here it change things that before 4/7 were really used as both stack 
> pointers and thread_info pointers.

What uses it as a thread_info pointer? It seems more like a stack
with some amount of unused space in it but that's all.

That said I don't care to nitpick too much where things go exactly
if you like it better here that's fine.

Thanks,
Nick