linux-kernel - Re: [PATCH 04/35] lmb: Add lmb_find

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Date:	Thu, 13 May 2010 23:25:56 -0700
From:	Yinghai <yinghai.lu@...cle.com>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
CC:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Miller <davem@...emloft.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Johannes Weiner <hannes@...xchg.org>,
	linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org
Subject: Re: [PATCH 04/35] lmb: Add lmb_find_area()

On 05/13/2010 07:16 PM, Benjamin Herrenschmidt wrote:
> On Thu, 2010-05-13 at 17:19 -0700, Yinghai Lu wrote:
>> it is a wrapper for lmb_find_base
>>
>> make it more easy for x86 to use lmb. ( rebase )
>> x86 early_res is using find/reserve pattern instead of alloc.
>>
>> -v2: Change name to lmb_find_area() according to Michael Ellerman
>> -v3: Add generic weak version __lmb_find_area()
>>      so keep the path for fallback to x86 version that handle from low
>>
>> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
>> ---
>>  include/linux/lmb.h |    4 ++++
>>  lib/lmb.c           |   27 ++++++++++++++++++++++++++-
>>  2 files changed, 30 insertions(+), 1 deletions(-)
>>
>> diff --git a/include/linux/lmb.h b/include/linux/lmb.h
>> index 0b073a3..3c23dc8 100644
>> --- a/include/linux/lmb.h
>> +++ b/include/linux/lmb.h
>> @@ -44,6 +44,10 @@ extern struct lmb lmb;
>>  extern int lmb_debug;
>>  extern struct lmb_region lmb_reserved_init_regions[];
>>  
>> +u64 __lmb_find_area(u64 ei_start, u64 ei_last, u64 start, u64 end,
>> +			u64 size, u64 align);
>> +u64 lmb_find_area(u64 start, u64 end, u64 size, u64 align);
> 
> See my comments about sorting out the return from that function.
> 
> Also, I don't understand the need for that __ version. It looks like
> something you should keep inside x86, I don't see the need for it in the
> generic LMB code, since it just does trivial cropping of the arguments.

otherwise need to export lmb_find_base() and LMB_ERROR

> 
> Also "ei_last" and "ei_start" are pretty bad names for its arguments
> anyways. To some extent I wonder if the caller should be responsible for
> doing the cropping in the first place.

yes. but need that to keep switch from early_res/nobootmem to lmb/nobootmem smooth.

will clean it after early_res is replaced.

> 
> Cheers,
> Ben.
> 
>>  extern void __init lmb_init(void);
>>  extern void __init lmb_analyze(void);
>>  extern long lmb_add(phys_addr_t base, phys_addr_t size);
>> diff --git a/lib/lmb.c b/lib/lmb.c
>> index 6d49a17..f917dbf 100644
>> --- a/lib/lmb.c
>> +++ b/lib/lmb.c
>> @@ -155,6 +155,31 @@ static phys_addr_t __init lmb_find_base(phys_addr_t size, phys_addr_t align,
>>  	return LMB_ERROR;
>>  }
>>  
>> +u64 __init __weak __lmb_find_area(u64 ei_start, u64 ei_last, u64 start, u64 end,
>> +				 u64 size, u64 align)
>> +{
>> +	u64 final_start, final_end;
>> +	u64 mem;
>> +
>> +	final_start = max(ei_start, start);
>> +	final_end = min(ei_last, end);
>> +
>> +	if (final_start >= final_end)
>> +		return LMB_ERROR;
>> +
>> +	mem = lmb_find_base(size, align, final_start, final_end);
>> +
>> +	return mem;
>> +}
>> +
>> +/*
>> + * Find a free area with specified alignment in a specific range.
>> + */
>> +u64 __init __weak lmb_find_area(u64 start, u64 end, u64 size, u64 align)
>> +{
>> +	return lmb_find_base(size, align, start, end);
>> +}
>> +
>>  static void __init_lmb lmb_remove_region(struct lmb_type *type, unsigned long r)
>>  {
>>  	unsigned long i;
>> @@ -199,7 +224,7 @@ static int __init_lmb lmb_double_array(struct lmb_type *type)
>>  		new_array = kmalloc(new_size, GFP_KERNEL);
>>  		addr = new_array == NULL ? LMB_ERROR : __pa(new_array);
>>  	} else
>> -		addr = lmb_find_base(new_size, sizeof(struct lmb_region), 0, LMB_ALLOC_ACCESSIBLE);
>> +		addr = lmb_find_area(0, lmb.current_limit, new_size, sizeof(struct lmb_region));
>>  	if (addr == LMB_ERROR) {
>>  		pr_err("lmb: Failed to double %s array from %ld to %ld entries !\n",
>>  		       lmb_type_name(type), type->max, type->max * 2);
> 

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