linux-kernel - Re: [PATCH v2] PCI: endpoint: functions: Use kmemdup instead of duplicating its function

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Message-ID: <ba5489d4-671b-5b52-3917-ea478f7233e0@synopsys.com>
Date:   Mon, 11 Feb 2019 09:15:14 +0000
From:   Gustavo Pimentel <gustavo.pimentel@...opsys.com>
To:     Kishon Vijay Abraham I <kishon@...com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Wen Yang <wen.yang99@....com.cn>
CC:     Bjorn Helgaas <bhelgaas@...gle.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "zhong.weidong@....com.cn" <zhong.weidong@....com.cn>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        Niklas Cassel <niklas.cassel@...s.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Cyrille Pitchen <cyrille.pitchen@...e-electrons.com>
Subject: Re: [PATCH v2] PCI: endpoint: functions: Use kmemdup instead of
 duplicating its function

On 11/02/2019 05:48, Kishon Vijay Abraham I wrote:
> Hi Lorenzo,
> 
> On 08/02/19 5:50 PM, Lorenzo Pieralisi wrote:
>> On Thu, Dec 06, 2018 at 08:52:25PM +0800, Wen Yang wrote:
>>> kmemdup has implemented the function that kmalloc() + memcpy().
>>> We prefer to kmemdup rather than code opened implementation.
>>>
>>> This issue was detected with the help of coccinelle.
>>>
>>> Signed-off-by: Wen Yang <wen.yang99@....com.cn>
>>> CC: Kishon Vijay Abraham I <kishon@...com>
>>> CC: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
>>> CC: Bjorn Helgaas <bhelgaas@...gle.com>
>>> CC: Gustavo Pimentel <gustavo.pimentel@...opsys.com>
>>> CC: Niklas Cassel <niklas.cassel@...s.com>
>>> CC: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>>> CC: Cyrille Pitchen <cyrille.pitchen@...e-electrons.com>
>>> CC: linux-pci@...r.kernel.org (open list:PCI ENDPOINT SUBSYSTEM)
>>> CC: linux-kernel@...r.kernel.org (open list)
>>> ---
>>>  drivers/pci/endpoint/functions/pci-epf-test.c | 4 +---
>>>  1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> Kishon,
>>
>> this looks OK to me, anything I am missing ?
> 
> For the existing code this might seem the right thing to do but ideally the
> memcpy here should be changed to memcpy_fromio/memcpy_toio.
> 
> Also later when we plan to use DMA (on the endpoint) for data transfer, we have
> to use kzalloc and dma_map_single APIs.

Are you considering to use the eDMA driver that I'm developing?

> 
> So maybe the right thing would be to just fix it to use memcpy_fromio here.
> 
> Thanks
> Kishon
>>
>> Lorenzo
>>
>>> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
>>> index 3e86fa3c7da3..8df6c019f8a2 100644
>>> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
>>> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
>>> @@ -169,14 +169,12 @@ static int pci_epf_test_read(struct pci_epf_test *epf_test)
>>>  		goto err_addr;
>>>  	}
>>>  
>>> -	buf = kzalloc(reg->size, GFP_KERNEL);
>>> +	buf = kmemdup(src_addr, reg->size, GFP_KERNEL);
>>>  	if (!buf) {
>>>  		ret = -ENOMEM;
>>>  		goto err_map_addr;
>>>  	}
>>>  
>>> -	memcpy(buf, src_addr, reg->size);
>>> -
>>>  	crc32 = crc32_le(~0, buf, reg->size);
>>>  	if (crc32 != reg->checksum)
>>>  		ret = -EIO;
>>> -- 
>>> 2.19.1
>>>