linux-kernel - Re: [PATCH 2/4] mm: cma: Always consider a 0 base address reservation as dynamic

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Date:	Fri, 24 Oct 2014 02:50:42 +0300
From:	Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:	Michal Nazarewicz <mina86@...a86.com>
Cc:	Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-sh@...r.kernel.org,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH 2/4] mm: cma: Always consider a 0 base address reservation as dynamic

Hi Michal,

On Thursday 23 October 2014 18:55:20 Michal Nazarewicz wrote:
> On Thu, Oct 23 2014, Laurent Pinchart wrote:
> > The fixed parameter to cma_declare_contiguous() tells the function
> > whether the given base address must be honoured or should be considered
> > as a hint only. The API considers a zero base address as meaning any
> > base address, which must never be considered as a fixed value.
> > 
> > Part of the implementation correctly checks both fixed and base != 0,
> > but two locations check the fixed value only. Set fixed to false when
> > base is 0 to fix that and simplify the code.
> > 
> > Signed-off-by: Laurent Pinchart
> > <laurent.pinchart+renesas@...asonboard.com>
> 
> Acked-by: Michal Nazarewicz <mina86@...a86.com>
> 
> And like before, this should also probably also go to stable.

v3.17 and older don't have the extra fixed checks, so I don't think there's a 
need to Cc stable.

> > ---
> > 
> >  mm/cma.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/mm/cma.c b/mm/cma.c
> > index 16c6650..6b14346 100644
> > --- a/mm/cma.c
> > +++ b/mm/cma.c
> > @@ -239,6 +239,9 @@ int __init cma_declare_contiguous(phys_addr_t base,
> >  	size = ALIGN(size, alignment);
> >  	limit &= ~(alignment - 1);
> > 
> > +	if (!base)
> > +		fixed = false;
> > +
> >  	/* size should be aligned with order_per_bit */
> >  	if (!IS_ALIGNED(size >> PAGE_SHIFT, 1 << order_per_bit))
> >  		return -EINVAL;
> > @@ -262,7 +265,7 @@ int __init cma_declare_contiguous(phys_addr_t base,
> >  	}
> >  	
> >  	/* Reserve memory */
> > -	if (base && fixed) {
> > +	if (fixed) {
> >  		if (memblock_is_region_reserved(base, size) ||
> >  		    memblock_reserve(base, size) < 0) {
> >  			ret = -EBUSY;

-- 
Regards,

Laurent Pinchart

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