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

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Message-ID: <CAK7LNAQiO0Jx-qp=-pGWeknAbcTsf9VBPDdR65BP-5f3c4hXEA@mail.gmail.com>
Date:   Fri, 7 Apr 2017 15:49:23 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     Leonard Crestez <leonard.crestez@....com>
Cc:     linux-mtd@...ts.infradead.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        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>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Octavian Purdila <octavian.purdila@....com>
Subject: Re: [PATCH v3 33/37] mtd: nand: allocate aligned buffers if
 NAND_OWN_BUFFERS is unset

Hi Leonard,

2017-04-06 23:08 GMT+09:00 Leonard Crestez <leonard.crestez@....com>:
> On Thu, Mar 30, 2017 at 11:15 AM, 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>
>
>> @@ -4914,8 +4930,12 @@ void nand_cleanup(struct nand_chip *chip)
>> >         /* Free bad block table memory */
>>         kfree(chip->bbt);
>> -       if (!(chip->options & NAND_OWN_BUFFERS))
>> +       if (!(chip->options & NAND_OWN_BUFFERS)) {
>> +               kfree(chip->buffers->databuf);
>> +               kfree(chip->buffers->ecccode);
>> +               kfree(chip->buffers->ecccalc);
>>                 kfree(chip->buffers);
>> +       }
>
> It seems that chip->buffers might not be allocated at this point, for
> example if nand_cleanup is called during a failed probe. You should
> check if (chip->buffers != NULL) before freeing stuff inside it.

You are right.

The failure path in NAND drivers is messy.   :-(
nand_cleanup() may be called before nand_scan_tail()
finishes successfully...

I will send a fixup patch.  Thanks!



-- 
Best Regards
Masahiro Yamada