From: nicolas.ferre@atmel•com (Nicolas Ferre)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] mtd: atmel_nand: fix bug driver will in a dead lock if no nand detected
Date: Thu, 7 Nov 2013 11:55:07 +0100 [thread overview]
Message-ID: <527B718B.7060806@atmel.com> (raw)
In-Reply-To: <527B6ADF.1090201@atmel.com>
On 07/11/2013 11:26, Josh Wu :
> Hi, Brian
>
> On 11/7/2013 4:39 PM, Brian Norris wrote:
>> Hi Josh,
>>
>> On Tue, Nov 05, 2013 at 05:59:07PM +0800, Josh Wu wrote:
>>> In the atmel driver probe function, the code shows like following:
>>> atmel_nand_probe(...) {
>>> ...
>>>
>>> err_nand_ioremap:
>>> platform_driver_unregister(&atmel_nand_nfc_driver);
>>> return res;
>>> }
>>>
>>> If no nand flash detected, the driver probe function will goto
>>> err_nand_ioremap label.
>>> Then platform_driver_unregister() will be called. It will get the
>>> lock of atmel_nand device since it is parent of nfc_device. The
>>> problem is the lock is already hold by atmel_nand_probe itself.
>>> So system will be in a dead lock.
>>>
>>> This patch just simply removed to platform_driver_unregister() call.
>>> When atmel_nand driver is quit the platform_driver_unregister() will
>>> be called in atmel_nand_remove().
>> The real key, here, is that the platform-driver probe() has no business
>> un-registering another driver, right?
>
> right.
>
>> Shouldn't both drivers just be
>> registered/unregistered in the module init/exit, and not in probe()?
>
> currently the NFC driver is registered in the beginning of nand probe
> function. After NFC driver is initialized, the rest of the nand probe
> function
> will check the NFC driver status.
> I am not sure it is proper to registered another driver in a probe().
>
>>
>> Also, should this be marked for -stable?
>
> Shouldn't cc to stable after the patch is merged in mtd mail list?
Whether you add a Cc: tag in your signature location or you send another
patch to the stable mailing list *but* only when the patch is accepted
in Linus' git tree.
You can find the information in
Documentation/stable_kernel_rules.txt
Bye,
>>> Signed-off-by: Josh Wu <josh.wu@atmel•com>
>>> ---
>>> drivers/mtd/nand/atmel_nand.c | 1 -
>>> 1 file changed, 1 deletion(-)
>>>
>>> diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c
>>> index ef9c9f5..469d4e2 100644
>>> --- a/drivers/mtd/nand/atmel_nand.c
>>> +++ b/drivers/mtd/nand/atmel_nand.c
>>> @@ -2142,7 +2142,6 @@ err_no_card:
>>> if (host->dma_chan)
>>> dma_release_channel(host->dma_chan);
>>> err_nand_ioremap:
>>> - platform_driver_unregister(&atmel_nand_nfc_driver);
>>> return res;
>>> }
>>>
>> Brian
>
>
>
--
Nicolas Ferre
next prev parent reply other threads:[~2013-11-07 10:55 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-05 9:59 [PATCH] mtd: atmel_nand: fix bug driver will in a dead lock if no nand detected Josh Wu
2013-11-07 8:39 ` Brian Norris
2013-11-07 10:26 ` Josh Wu
2013-11-07 10:55 ` Nicolas Ferre [this message]
2013-11-07 18:09 ` Brian Norris
2013-11-08 3:46 ` Josh Wu
2013-11-13 0:10 ` Brian Norris
2013-11-13 3:26 ` Josh Wu
2013-11-13 8:44 ` Brian Norris
2013-11-13 10:33 ` Nicolas Ferre
2013-11-07 18:43 ` Brian Norris
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=527B718B.7060806@atmel.com \
--to=nicolas.ferre@atmel$(echo .)com \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox