linux-kernel - Re: [PATCH 07/14] pci: don't shrink bridge resources

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Message-ID: <4B50D98B.3000801@kernel.org>
Date:	Fri, 15 Jan 2010 13:09:31 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Jesse Barnes <jbarnes@...tuousgeek.org>
CC:	Ingo Molnar <mingo@...e.hu>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ivan Kokshaysky <ink@...assic.park.msu.ru>,
	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>,
	Alex Chiang <achiang@...com>,
	Bjorn Helgaas <bjorn.helgaas@...com>,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH 07/14] pci: don't shrink bridge resources

On 01/15/2010 11:04 AM, Jesse Barnes wrote:
> On Tue, 22 Dec 2009 15:02:27 -0800
> Yinghai Lu <yinghai@...nel.org> wrote:
> 
>> when we are clearing leaf bridge resource and try to get big one, we
>> could shrink the bridge if there is no resource under it.
>>
>> let check with old resource size and make sure we are trying to get
>> big one.
>>
>> -v2: keep disable window print out, still could happen on non pci
>> hotplug system
>>
>> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
>> ---
>>  drivers/pci/setup-bus.c |   14 ++++++++++++--
>>  1 files changed, 12 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
>> index 9bb4435..d53b42e 100644
>> --- a/drivers/pci/setup-bus.c
>> +++ b/drivers/pci/setup-bus.c
>> @@ -387,7 +387,7 @@ static void pbus_size_io(struct pci_bus *bus,
>> resource_size_t min_size) {
>>  	struct pci_dev *dev;
>>  	struct resource *b_res = find_free_bus_resource(bus,
>> IORESOURCE_IO);
>> -	unsigned long size = 0, size1 = 0;
>> +	unsigned long size = 0, size1 = 0, old_size;
>>  
>>  	if (!b_res)
>>   		return;
>> @@ -412,12 +412,17 @@ static void pbus_size_io(struct pci_bus *bus,
>> resource_size_t min_size) }
>>  	if (size < min_size)
>>  		size = min_size;
>> +	old_size = resource_size(b_res);
>> +	if (old_size == 1)
>> +		old_size = 0;
> 
> Do we even need these == 1 checks?  If old_size really was 1, it means
> we had a very small decode range.  Might make more sense to do...

when start=0 and end =0, will get old_size = 1

> 
>>  /* To be fixed in 2.5: we should have sort of HAVE_ISA
>>     flag in the struct pci_bus. */
>>  #if defined(CONFIG_ISA) || defined(CONFIG_EISA)
>>  	size = (size & 0xff) + ((size & ~0xffUL) << 2);
>>  #endif
>>  	size = ALIGN(size + size1, 4096);
>> +	if (size < old_size)
>> +		size = old_size;
> 
> if (size && size < old_size)
> 
> here instead?  Just a nit because the if (old_size == 1) seemed a bit
> magical at first.  Same thing applies later on.
> 

no

it will shrink.

YH
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