linux-kernel - RE: [PATCH v6 1/3] genalloc:support memory-allocation with bytes-alignment to genalloc

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Date:	Tue, 25 Aug 2015 02:40:09 +0000
From:	Zhao Qiang <qiang.zhao@...escale.com>
To:	Laura Abbott <labbott@...hat.com>,
	Scott Wood <scottwood@...escale.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
	"lauraa@...eaurora.org" <lauraa@...eaurora.org>,
	Xiaobo Xie <X.Xie@...escale.com>,
	"benh@...nel.crashing.org" <benh@...nel.crashing.org>,
	Li Leo <LeoLi@...escale.com>,
	"paulus@...ba.org" <paulus@...ba.org>
Subject: RE: [PATCH v6 1/3] genalloc:support memory-allocation with
 bytes-alignment to genalloc

On 08/25/2015 07:11 AM, Laura Abbott wrote:
> -----Original Message-----
> From: Laura Abbott [mailto:labbott@...hat.com]
> Sent: Tuesday, August 25, 2015 7:11 AM
> To: Zhao Qiang-B45475; Wood Scott-B07421
> Cc: linux-kernel@...r.kernel.org; linuxppc-dev@...ts.ozlabs.org;
> lauraa@...eaurora.org; Xie Xiaobo-R63061; benh@...nel.crashing.org; Li
> Yang-Leo-R58472; paulus@...ba.org
> Subject: Re: [PATCH v6 1/3] genalloc:support memory-allocation with
> bytes-alignment to genalloc
> 
> On 08/24/2015 02:31 AM, Zhao Qiang wrote:
> > Bytes alignment is required to manage some special RAM, so add
> > gen_pool_first_fit_align to genalloc, meanwhile add
> > gen_pool_alloc_data to pass data to gen_pool_first_fit_align(modify
> > gen_pool_alloc as a wrapper)
> >
> > Signed-off-by: Zhao Qiang <qiang.zhao@...escale.com>
> > ---
> > Changes for v6:
> > 	- patches set v6 include a new patch because of using
> > 	- genalloc to manage QE MURAM, patch 0001 is the new
> > 	- patch, adding bytes alignment for allocation for use.
> >
> >   include/linux/genalloc.h | 23 +++++++++++++++----
> >   lib/genalloc.c           | 58
> +++++++++++++++++++++++++++++++++++++++++++-----
> >   2 files changed, 72 insertions(+), 9 deletions(-)
> >
> > diff --git a/include/linux/genalloc.h b/include/linux/genalloc.h index
> > 1ccaab4..55da07e 100644
> > --- a/include/linux/genalloc.h
> > +++ b/include/linux/genalloc.h
> > @@ -34,6 +34,7 @@
> >
> >   struct device;
> >   struct device_node;
> > +struct gen_pool;
> >
> >   /**
> >    * Allocation callback function type definition @@ -47,7 +48,7 @@
> > typedef unsigned long (*genpool_algo_t)(unsigned long *map,
> >   			unsigned long size,
> >   			unsigned long start,
> >   			unsigned int nr,
> > -			void *data);
> > +			void *data, struct gen_pool *pool);
> >
> >   /*
> >    *  General purpose special memory pool descriptor.
> > @@ -73,6 +74,13 @@ struct gen_pool_chunk {
> >   	unsigned long bits[0];		/* bitmap for allocating memory chunk
> */
> >   };
> >
> > +/*
> > + *  gen_pool data descriptor for gen_pool_first_fit_align.
> > + */
> > +struct genpool_data_align {
> > +	int align;		/* alignment by bytes for starting address */
> > +};
> > +
> 
> (sorry for chiming in late, I've been traveling)
> 
> Is there an advantage here to wrapping this in a structure instead of
> just passing a pointer to an align integer?


Please look at the commit message for
ca279cf1065fb689abea1dc7d8c11787729bb185 which adds "data":

"As I can't predict all the possible requirements/needs for all allocation    
uses cases, I add a "free" field 'void *data' to pass any needed     
information to the allocation function.  For example 'data' could be used     
to handle a structure where you store the alignment, the expected memory     
bank, the requester device, or any information that could influence the     
allocation algorithm."

> 
> Thanks,
> Laura
-Zhao 
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