linux-kernel - Re: [PATCH] mtd: avoid registering reboot notifier twice

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Date:	Mon, 02 Feb 2015 08:08:17 +0100
From:	Niklas Cassel <nks@...wful.org>
To:	Brian Norris <computersforpeace@...il.com>
CC:	dwmw2@...radead.org, linux-mtd@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mtd: avoid registering reboot notifier twice


On 02/02/2015 12:07 AM, Brian Norris wrote:
> On Sun, Feb 01, 2015 at 02:08:50AM +0100, Niklas Cassel wrote:
>> Calling mtd_device_parse_register with the same mtd_info
>> (e.g. registering several partitions on a single device)
>> would add the same reboot notifier twice, causing an
>> infinte loop in notifier_chain_register during boot up.
> No driver should be calling mtd_device_parse_register() multiple times
> on the same mtd_info. Under what context do you see this? What driver?
arch/cris/arch-v32/drivers/axisflashmap.c

It calls mtd_device_register for different partitions on same device using the same mtd_info.

What do you suggest this driver should do instead?

>
>> Signed-off-by: Niklas Cassel <nks@...wful.org>
>> ---
>>  drivers/mtd/mtdcore.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
>> index de79576..98efc1e 100644
>> --- a/drivers/mtd/mtdcore.c
>> +++ b/drivers/mtd/mtdcore.c
>> @@ -556,7 +556,7 @@ int mtd_device_parse_register(struct mtd_info *mtd, const char * const *types,
>>  			err = -ENODEV;
>>  	}
>>  
>> -	if (mtd->_reboot) {
>> +	if (mtd->_reboot && !mtd->reboot_notifier.notifier_call) {
>>  		mtd->reboot_notifier.notifier_call = mtd_reboot_notifier;
>>  		register_reboot_notifier(&mtd->reboot_notifier);
>>  	}
> Brian

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