netdev - Re: [PATCH v5 10/27] cxl: harden resource_contains checks to handle zero size resources

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Message-ID: <78cfa71b-5501-b79d-477c-c3a67340d60a@amd.com>
Date: Wed, 20 Nov 2024 13:45:54 +0000
From: Alejandro Lucero Palau <alucerop@....com>
To: Zhi Wang <zhiw@...dia.com>, alejandro.lucero-palau@....com
Cc: linux-cxl@...r.kernel.org, netdev@...r.kernel.org,
 dan.j.williams@...el.com, martin.habets@...inx.com, edward.cree@....com,
 davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com, edumazet@...gle.com
Subject: Re: [PATCH v5 10/27] cxl: harden resource_contains checks to handle
 zero size resources


On 11/19/24 19:50, Zhi Wang wrote:
> On Mon, 18 Nov 2024 16:44:17 +0000
> <alejandro.lucero-palau@....com> wrote:
>
>> From: Alejandro Lucero <alucerop@....com>
>>
>> For a resource defined with size zero, resource_contains returns
>> always true.
>>
>> Add resource size check before using it.
>>
> Does this trigger a bug? Looks like this should be with a Fixes: tag?


It seems it does not until the new code for type2 support.


> Z.
>
>> Signed-off-by: Alejandro Lucero <alucerop@....com>
>> ---
>>   drivers/cxl/core/hdm.c | 7 +++++--
>>   1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
>> index 223c273c0cd1..c58d6b8f9b58 100644
>> --- a/drivers/cxl/core/hdm.c
>> +++ b/drivers/cxl/core/hdm.c
>> @@ -327,10 +327,13 @@ static int __cxl_dpa_reserve(struct
>> cxl_endpoint_decoder *cxled, cxled->dpa_res = res;
>>   	cxled->skip = skipped;
>>   
>> -	if (resource_contains(&cxlds->pmem_res, res))
>> +	if (resource_size(&cxlds->pmem_res) &&
>> +	    resource_contains(&cxlds->pmem_res, res)) {
>>   		cxled->mode = CXL_DECODER_PMEM;
>> -	else if (resource_contains(&cxlds->ram_res, res))
>> +	} else if (resource_size(&cxlds->ram_res) &&
>> +		   resource_contains(&cxlds->ram_res, res)) {
>>   		cxled->mode = CXL_DECODER_RAM;
>> +	}
>>   	else {
>>   		dev_warn(dev, "decoder%d.%d: %pr mixed mode not
>> supported\n", port->id, cxled->cxld.id, cxled->dpa_res);