linux-kernel - Re: [PATCH v3 33/37] mtd: nand: allocate aligned buffers if NAND_OWN

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Date:   Mon, 10 Apr 2017 09:20:18 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     Boris Brezillon <boris.brezillon@...e-electrons.com>
Cc:     linux-mtd@...ts.infradead.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Marek Vasut <marek.vasut@...il.com>,
        Dinh Nguyen <dinguyen@...nel.org>,
        Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>,
        Graham Moore <grmoore@...nsource.altera.com>,
        Enrico Jorns <ejo@...gutronix.de>,
        Chuanxiao Dong <chuanxiao.dong@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Jassi Brar <jaswinder.singh@...aro.org>
Subject: Re: [PATCH v3 33/37] mtd: nand: allocate aligned buffers if
 NAND_OWN_BUFFERS is unset

Hi Boris,


2017-04-09 23:17 GMT+09:00 Boris Brezillon <boris.brezillon@...e-electrons.com>:
> On Thu, 30 Mar 2017 17:15:04 +0900
> Masahiro Yamada <yamada.masahiro@...ionext.com> wrote:
>
>> Some NAND controllers are using DMA engine requiring a specific
>> buffer alignment.  The core provides no guarantee on the nand_buffers
>> pointers, which forces some drivers to allocate their own buffers
>> and pass the NAND_OWN_BUFFERS flag.
>>
>> Rework the nand_buffers allocation logic to allocate each buffer
>> independently.  This should make most NAND controllers/DMA engine
>> happy, and allow us to get rid of these custom buf allocation in
>> NAND controller drivers.
>>
>> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
>> ---
>>
>> Changes in v3:
>>   - Reword git-log
>>
>> Changes in v2:
>>   - Newly added
>>
>>  drivers/mtd/nand/nand_base.c | 34 +++++++++++++++++++++++++++-------
>>  1 file changed, 27 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
>> index f828ad7..e9d3195 100644
>> --- a/drivers/mtd/nand/nand_base.c
>> +++ b/drivers/mtd/nand/nand_base.c
>> @@ -4613,13 +4613,25 @@ int nand_scan_tail(struct mtd_info *mtd)
>>       }
>>
>>       if (!(chip->options & NAND_OWN_BUFFERS)) {
>> -             nbuf = kzalloc(sizeof(*nbuf) + mtd->writesize
>> -                             + mtd->oobsize * 3, GFP_KERNEL);
>> +             nbuf = kzalloc(sizeof(*nbuf), GFP_KERNEL);
>>               if (!nbuf)
>>                       return -ENOMEM;
>> -             nbuf->ecccalc = (uint8_t *)(nbuf + 1);
>> -             nbuf->ecccode = nbuf->ecccalc + mtd->oobsize;
>> -             nbuf->databuf = nbuf->ecccode + mtd->oobsize;
>> +             nbuf->ecccalc = kmalloc(mtd->oobsize, GFP_KERNEL);
>> +             if (!nbuf->ecccalc) {
>> +                     ret = -EINVAL;
>> +                     goto err_free;
>
> You have a memory leak here, because chip->buffers = nbuf is only done
> after all allocations have succeeded.


Indeed.


>> +             }
>> +             nbuf->ecccode = kmalloc(mtd->oobsize, GFP_KERNEL);
>> +             if (!nbuf->ecccode) {
>> +                     ret = -EINVAL;
>
>                         ret = -ENOMEM;
>
> I have the following fixup patch, let me know if you're okay with it
> and I'll squash it in the original commit.


Thank you for your fixup patch.  The code-diff looks all good.
Please squash this.

Sorry for my many mistakes.







-- 
Best Regards
Masahiro Yamada