linux-kernel - Re: [PATCH] mmc: change to use kmalloc

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Date:	Wed, 11 Nov 2015 16:17:46 -0500
From:	Peter Hurley <peter@...leysoftware.com>
To:	Alim Akhtar <alim.akhtar@...il.com>,
	yalin wang <yalin.wang2010@...il.com>
Cc:	Ulf Hansson <ulf.hansson@...aro.org>,
	Adrian Hunter <adrian.hunter@...el.com>, ben@...adent.org.uk,
	Jaehoon Chung <jh80.chung@...sung.com>, asaf.vertz@...demg.com,
	tklauser@...tanz.ch, jonathanh@...dia.com,
	"James E.J. Bottomley" <JBottomley@...n.com>,
	Grant Grundler <grundler@...omium.org>,
	"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mmc: change to use kmalloc

On 11/11/2015 12:02 PM, Alim Akhtar wrote:
> Hi Yalin,
> 
> On Wed, Nov 11, 2015 at 9:53 AM, yalin wang <yalin.wang2010@...il.com> wrote:
>> Use kmalloc instead of kzalloc, zero the memory is not needed.
>>
> why you want to do this? what problem you faces, and how this resolves the same?

The patch fixes an inefficiency: explicitly zeroing memory that is then
immediately overwritten 6 lines below is wasteful.

Regards,
Peter Hurley

>> Signed-off-by: yalin wang <yalin.wang2010@...il.com>
>> ---
>>  drivers/mmc/card/block.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
>> index 23b6c8e..975cd3e 100644
>> --- a/drivers/mmc/card/block.c
>> +++ b/drivers/mmc/card/block.c
>> @@ -365,7 +365,7 @@ static struct mmc_blk_ioc_data *mmc_blk_ioctl_copy_from_user(
>>         if (!idata->buf_bytes)
>>                 return idata;
>>
>> -       idata->buf = kzalloc(idata->buf_bytes, GFP_KERNEL);
>> +       idata->buf = kmalloc(idata->buf_bytes, GFP_KERNEL);
>>         if (!idata->buf) {
>>                 err = -ENOMEM;
>>                 goto idata_err;
>> --
>> 1.9.1

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