linux-kernel - Re: [PATCH 1/2] take the segment adding out of locate_mem

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Date:	Wed, 13 Aug 2014 05:53:14 +0800
From:	Baoquan He <bhe@...hat.com>
To:	Vivek Goyal <vgoyal@...hat.com>
Cc:	linux-kernel@...r.kernel.org, ebiederm@...ssion.com, hpa@...or.com,
	akpm@...ux-foundation.org
Subject: Re: [PATCH 1/2] take the segment adding out of locate_mem_hole
 functions

On 08/12/14 at 05:00pm, Vivek Goyal wrote:
> On Tue, Aug 12, 2014 at 01:29:27PM +0800, Baoquan He wrote:
> > In locate_mem_hole functions, a memory hole is located and added as
> > kexec_segment. But from the name of locate_mem_hole, it should only
> > take responsibility of searching a available memory hole to contain
> > data of a specified size.
> > 
> > So in this patch add a new field 'mem' into kexec_buf, then take that
> > kexec segment adding code out of locate_mem_hole_top_down and
> > locate_mem_hole_bottom_up. This make clear of the functionality of
> > locate_mem_hole just like it declars to do. And by this
> > locate_mem_hole_callback chould be used later if anyone want to locate
> > a memory hole for other use.
> > 
> > Signed-off-by: Baoquan He <bhe@...hat.com>
> > ---
> >  include/linux/kexec.h | 1 +
> >  kernel/kexec.c        | 9 +++++----
> >  2 files changed, 6 insertions(+), 4 deletions(-)
> > 
> > diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> > index 4b2a0e1..9d957b7 100644
> > --- a/include/linux/kexec.h
> > +++ b/include/linux/kexec.h
> > @@ -178,6 +178,7 @@ struct kexec_buf {
> >  	struct kimage *image;
> >  	char *buffer;
> >  	unsigned long bufsz;
> > +	unsigned long mem;
> >  	unsigned long memsz;
> >  	unsigned long buf_align;
> >  	unsigned long buf_min;
> > diff --git a/kernel/kexec.c b/kernel/kexec.c
> > index 0b49a0a..586444e 100644
> > --- a/kernel/kexec.c
> > +++ b/kernel/kexec.c
> > @@ -2054,8 +2054,7 @@ static int locate_mem_hole_top_down(unsigned long start, unsigned long end,
> >  	} while (1);
> >  
> >  	/* If we are here, we found a suitable memory range */
> > -	__kexec_add_segment(image, kbuf->buffer, kbuf->bufsz, temp_start, > -			    kbuf->memsz);
> > +	kbuf->mem = temp_start;
> >  
> >  	/* Success, stop navigating through remaining System RAM ranges */
> >  	return 1;
> > @@ -2089,8 +2088,7 @@ static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end,
> >  	} while (1);
> >  
> >  	/* If we are here, we found a suitable memory range */
> > -	__kexec_add_segment(image, kbuf->buffer, kbuf->bufsz, temp_start,
> > -			    kbuf->memsz);
> > +	kbuf->mem = temp_start;
> >  
> >  	/* Success, stop navigating through remaining System RAM ranges */
> >  	return 1;
> > @@ -2176,6 +2174,9 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
> >  		return -EADDRNOTAVAIL;
> >  	}
> >  
> > +	__kexec_add_segment(image, kbuf->buffer, kbuf->bufsz, kbuf->mem,
> > +			    kbuf->memsz);
> > +
> 
> I think let us open code this function then. That way we have to
> retreive ksegment pointer once and it is easy to read.
> 
>   	/* Found a suitable memory range */
> 	ksegment = &image->segment[image->nr_segments];
>         ksegment->kbuf = kbuf->buffer;
>         ksegment->bufsz = kbuf->bufsz;
>         ksegment->mem = kbuf->mem;
>         ksegment->memsz = kbuf->memsz;
>         image->nr_segments++;
> 	*load_addr = ksegment->mem;

Yes, it's good to me.

> 
> >  	/* Found a suitable memory range */
> >  	ksegment = &image->segment[image->nr_segments - 1];
> >  	*load_addr = ksegment->mem;
> 
> If possible, can you hold on to your cleanup patches for a bit. I want
> to post some patches to introduce a config option for new syscall and
> they will need to go in sooner. You can rebase your patches on top of
> that.

Sure, I can wait. Thanks for telling.

> 
> Thanks
> Vivek
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