linux-kernel - Re: [PATCH] ndtest: Remove redundant NULL check

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Date:   Tue, 23 Mar 2021 08:00:25 +0530
From:   Santosh Sivaraj <santosh@...six.org>
To:     Ira Weiny <ira.weiny@...el.com>,
        Jiapeng Chong <jiapeng.chong@...ux.alibaba.com>
Cc:     dan.j.williams@...el.com, vishal.l.verma@...el.com,
        dave.jiang@...el.com, linux-nvdimm@...ts.01.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ndtest: Remove redundant NULL check


Hi Ira,

Ira Weiny <ira.weiny@...el.com> writes:

> On Mon, Mar 22, 2021 at 06:00:40PM +0800, Jiapeng Chong wrote:
>> Fix the following coccicheck warnings:
>> 
>> ./tools/testing/nvdimm/test/ndtest.c:491:2-7: WARNING: NULL check before
>> some freeing functions is not needed.
>
> I don't think there is anything wrong with this patch specifically but why is
> buf not checked for null after the vmalloc?
>
> It seems to me that if size >= DIMM_SIZE and the vmalloc fails the gen pool
> allocation is going to be leaked.
>

If vmalloc fails, gen_pool_free will get called through ndtest_release_resource,
registered with devm_action. But we will still need to check for vmalloc fail.

I will fix that when I send my inject-error support for the driver.

Thanks,
Santosh

> Ira
>
>> 
>> Reported-by: Abaci Robot <abaci@...ux.alibaba.com>
>> Signed-off-by: Jiapeng Chong <jiapeng.chong@...ux.alibaba.com>
>> ---
>>  tools/testing/nvdimm/test/ndtest.c | 3 +--
>>  1 file changed, 1 insertion(+), 2 deletions(-)
>> 
>> diff --git a/tools/testing/nvdimm/test/ndtest.c b/tools/testing/nvdimm/test/ndtest.c
>> index 6862915..98b4a43 100644
>> --- a/tools/testing/nvdimm/test/ndtest.c
>> +++ b/tools/testing/nvdimm/test/ndtest.c
>> @@ -487,8 +487,7 @@ static void *ndtest_alloc_resource(struct ndtest_priv *p, size_t size,
>>  buf_err:
>>  	if (__dma && size >= DIMM_SIZE)
>>  		gen_pool_free(ndtest_pool, __dma, size);
>> -	if (buf)
>> -		vfree(buf);
>> +	vfree(buf);
>>  	kfree(res);
>>  
>>  	return NULL;
>> -- 
>> 1.8.3.1
>>