linux-kernel - Re: [PATCH v1 7/8] null_blk: add error handling support for add

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Message-ID: <096c9d6f-b765-ab70-098e-ab64d8b411df@suse.de>
Date:   Wed, 12 May 2021 19:28:16 +0200
From:   Hannes Reinecke <hare@...e.de>
To:     Luis Chamberlain <mcgrof@...nel.org>
Cc:     axboe@...nel.dk, bvanassche@....org, ming.lei@...hat.com,
        hch@...radead.org, jack@...e.cz, osandov@...com,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 7/8] null_blk: add error handling support for
 add_disk()

On 5/12/21 7:20 PM, Luis Chamberlain wrote:
> On Wed, May 12, 2021 at 07:12:03PM +0200, Hannes Reinecke wrote:
>> On 5/12/21 6:47 PM, Luis Chamberlain wrote:
>>> On Wed, May 12, 2021 at 05:16:39PM +0200, Hannes Reinecke wrote:
>>>> On 5/12/21 8:46 AM, Luis Chamberlain wrote:
>>>>> We never checked for errors on add_disk() as this function
>>>>> returned void. Now that this is fixed, use the shiny new
>>>>> error handling.
>>>>>
>>>>> Signed-off-by: Luis Chamberlain <mcgrof@...nel.org>
>>>>> ---
>>>>>     drivers/block/null_blk/main.c | 9 +++++++--
>>>>>     1 file changed, 7 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
>>>>> index 5f006d9e1472..2346d1292b26 100644
>>>>> --- a/drivers/block/null_blk/main.c
>>>>> +++ b/drivers/block/null_blk/main.c
>>>>> @@ -1699,6 +1699,7 @@ static int init_driver_queues(struct nullb *nullb)
>>>>>     static int null_gendisk_register(struct nullb *nullb)
>>>>>     {
>>>>> +	int ret;
>>>>>     	sector_t size = ((sector_t)nullb->dev->size * SZ_1M) >> SECTOR_SHIFT;
>>>>>     	struct gendisk *disk;
>>>>> @@ -1719,13 +1720,17 @@ static int null_gendisk_register(struct nullb *nullb)
>>>>>     	strncpy(disk->disk_name, nullb->disk_name, DISK_NAME_LEN);
>>>>>     	if (nullb->dev->zoned) {
>>>>> -		int ret = null_register_zoned_dev(nullb);
>>>>> +		ret = null_register_zoned_dev(nullb);
>>>>>     		if (ret)
>>>>>     			return ret;
>>>>>     	}
>>>>> -	add_disk(disk);
>>>>> +	ret = add_disk(disk);
>>>>> +	if (ret) {
>>>>
>>>> unregister_zoned_device() ?
>>>
>>> That function does not exist, do you mean null_free_zoned_dev()? If so
>>> that is done by the caller.
>>>
>> What I intended to say is that you are calling 'null_register_zoned_dev()'
>> at one point, but don't call a cleanup function if there is an error later
>> in the path, leaving the caller to guess whether null_register_zoned_dev()
>> has been called or not.
>> So we should call the cleanup function here, too.
> 
> The cleanup for zone stuff is done on the caller.
> 
My point being: how does he know?
The zone stuff might or might not be initialized.
Why not do the cleanup action in the error path of this function?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare@...e.de                              +49 911 74053 688
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