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SubjectRe: [PATCH V5] mtd: ubi: Extend UBI layer debug/messaging capabilities
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

>> 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;


@@ -970,7 +974,7 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num,

- 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);

>>> @@ -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....


+ ubi_msg(ubi, "hex dump of the %d-%d region",
+ offset, offset + len);


+ ubi_msg(ubi, "hex dump of the %d-%d region",
+ offset, offset + len);

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.



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