linux-kernel - Re: [PATCH v3 1/2] pci: endpoint: Simplify name allocation for epf device

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Date:   Tue, 27 Feb 2018 16:13:20 +0530
From:   Kishon Vijay Abraham I <kishon@...com>
To:     Rolf Evers-Fischer <embedded24@...rs-fischer.de>
CC:     <lorenzo.pieralisi@....com>, <bhelgaas@...gle.com>,
        <linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <andy.shevchenko@...il.com>,
        Rolf Evers-Fischer <rolf.evers.fischer@...iv.com>
Subject: Re: [PATCH v3 1/2] pci: endpoint: Simplify name allocation for epf
 device



On Tuesday 27 February 2018 03:45 PM, Rolf Evers-Fischer wrote:
> Hi,
> 
> On Tue, 27 Feb 2018, Kishon Vijay Abraham I wrote:
> 
>> Hi,
>>
>> On Tuesday 27 February 2018 03:32 PM, Rolf Evers-Fischer wrote:
>>> From: Rolf Evers-Fischer <rolf.evers.fischer@...iv.com>
>>>
>>> This commit replaces allocating and freeing the intermediate
>>> 'buf'/'func_name' with a combination of 'kstrndup()' and 'len'.
>>>
>>> 'len' is the required length of 'epf->name'.
>>> 'epf->name' should be either the first part of 'name' preceding the '.'
>>> or the complete 'name', if there is no '.' in the name.
>>>
>>> Signed-off-by: Rolf Evers-Fischer <rolf.evers.fischer@...iv.com>
>>> ---
>>>  drivers/pci/endpoint/pci-epf-core.c | 22 ++++------------------
>>>  1 file changed, 4 insertions(+), 18 deletions(-)
>>>
>>> diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c
>>> index 766ce1dca2ec..1f2506f32bb9 100644
>>> --- a/drivers/pci/endpoint/pci-epf-core.c
>>> +++ b/drivers/pci/endpoint/pci-epf-core.c
>>> @@ -200,8 +200,7 @@ struct pci_epf *pci_epf_create(const char *name)
>>>  	int ret;
>>>  	struct pci_epf *epf;
>>>  	struct device *dev;
>>> -	char *func_name;
>>> -	char *buf;
>>> +	int len;
>>>  
>>>  	epf = kzalloc(sizeof(*epf), GFP_KERNEL);
>>>  	if (!epf) {
>>> @@ -209,20 +208,11 @@ struct pci_epf *pci_epf_create(const char *name)
>>>  		goto err_ret;
>>>  	}
>>>  
>>> -	buf = kstrdup(name, GFP_KERNEL);
>>> -	if (!buf) {
>>> -		ret = -ENOMEM;
>>> -		goto free_epf;
>>> -	}
>>> -
>>> -	func_name = buf;
>>> -	buf = strchrnul(buf, '.');
>>> -	*buf = '\0';
>>> -
>>> -	epf->name = kstrdup(func_name, GFP_KERNEL);
>>> +	len = strchrnul(name, '.') - name;
>>> +	epf->name = kstrndup(name, len, GFP_KERNEL);
>>
>> shouldn't the string end with '\0'?
>>
> 
> I agree, it should end with '\0', but fortunately the 'kstrndup()' 
> function already adds it for us, see mm/util.c, line 100:
> 	(...)
> 	memcpy(buf, s, len);
> 	buf[len] = '\0';
> 	(...)

oh okay. missed that..

Acked-by: Kishon Vijay Abraham I <kishon@...com>
> 
> Kind regards
>  Rolf
>