linux-kernel - Re: [PATCH V5] mtd: ubi: Extend UBI layer debug/messaging capabilities

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Date:	Mon, 03 Nov 2014 09:15:51 +0200
From:	Tanya Brokhman <tlinder@...eaurora.org>
To:	hujianyang <hujianyang@...wei.com>
CC:	dedekind1@...il.com, ezequiel.garcia@...e-electrons.com,
	Richard Weinberger <richard@....at>,
	open list <linux-kernel@...r.kernel.org>,
	linux-mtd@...ts.infradead.org, linux-arm-msm@...r.kernel.org,
	Brian Norris <computersforpeace@...il.com>,
	David Woodhouse <dwmw2@...radead.org>
Subject: Re: [PATCH V5] mtd: ubi: Extend UBI layer debug/messaging capabilities

On 11/3/2014 5:08 AM, hujianyang wrote:
> Hi Tanya,
>
> On 2014/11/3 1:14, Tanya Brokhman wrote:
>>>
>>> This patch add 'struct ubi_device *' for 3 functions. We can get 'ubi_device' from
>>> 'ubi_volume'. So I think it's because when we call these functions, the '->ubi'
>>> pointer of 'ubi_volume' is not initialized, am I right? This patch use 'vol->ubi'
>>> to indicate a 'struct ubi_device *' pointer in some places, I think you are sure
>>> of using them.
>>>
>>
>> 1. for validate_vid_hdr() we don;t have a ubi_volume yet since its part of the attach process so we need struct ubi_device
>> 2. for get_exclusive() - you're right. Will fetch dev number from the volume
>> 3. for check_av() - you're right. fixed
>>
>
> I'm not sure if 'ubi_volume->ubi' is initialized when we call some kinds of
> ubi_err() to print error messages. The reference to a null pointer, we perform
> 'ubi->ubi_num' in ubi_err(), may crash the kernel. So you should be careful
> of these situations not only in above cases but also in other places in your
> patch.
>
>>>
>>> We have the parameter 'ubi_num' for log in some functions like 'ubi_attach_mtd_dev'
>>> before. This patch remove 'ubi_num' in upper changes but keep it in other changes.
>>> Do we have a discussed rule to deal with this situation? It's not a big problem~
>>
>> I removed it because it made no sense printing it twice:
>> "ubi-0: attached mtd-0 (...) to ubi0"?
>> so I shortned the message:
>> "ubi-0: attched mtd..."
>> All the info is still there....
>> Same for other messages that printed ubi number.
>>
>
> Could we remove some the 'ubi_num'? I think there are no need to print it
> twice in other places, like:
>
> @@ -921,7 +923,7 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num,
>
>   		/* Make sure ubi_num is not busy */
>   		if (ubi_devices[ubi_num]) {
> -			ubi_err("ubi%d already exists", ubi_num);
> +			ubi_err(ubi, "ubi%d already exists", ubi_num);
>   			return -EEXIST;
>   		}
>   	}
>
> and
>
> @@ -970,7 +974,7 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num,
>   	mutex_init(&ubi->fm_mutex);
>   	init_rwsem(&ubi->fm_sem);
>
> -	ubi_msg("attaching mtd%d to ubi%d", mtd->index, ubi_num);
> +	ubi_msg(ubi, "attaching mtd%d to ubi%d", mtd->index, ubi_num);
>
>

yes, already removed

>>>> @@ -1415,8 +1418,9 @@ int ubi_self_check_all_ff(struct ubi_device *ubi, int pnum, int offset, int len)
>>>>        return 0;
>>>>
>>>>    fail:
>>>> -    ubi_err("self-check failed for PEB %d", pnum);
>>>> -    ubi_msg("hex dump of the %d-%d region", offset, offset + len);
>>>> +    ubi_err(ubi, "self-check failed for PEB %d", pnum);
>>>> +    ubi_msg(ubi, "hex dump of the %d-%d region",
>>>> +         offset, offset + len);
>>>>        print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1, buf, len, 1);
>>>>        err = -EINVAL;
>>>>    error:
>>>
>>> Artem, I know you have tried to align the message code in different lines, maybe
>>> you can check if you lose this one.
>>>
>>
>> hmmm... not sure I understand what is wrong here....
>>
>
> Turn
>
> +    ubi_msg(ubi, "hex dump of the %d-%d region",
> +         offset, offset + len);
>
> to
>
> +    ubi_msg(ubi, "hex dump of the %d-%d region",
> +            offset, offset + len);

Actually, I just made it all in one line.... thanks!

>
> Maybe like this. The next line aligns to the message in first line, not a big problem.
> By the way, I use space in this example, it's wrong. Tab is right.
>
>
> Thanks!
>
> Hu
>
>

Will upload new version soon. Just running some tests.

Thanks,
Tanya Brokhman
-- 
Qualcomm Israel, on behalf of Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
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