linux-kernel - Re: [f2fs-dev] [PATCH] f2fs: avoid to use a NULL point in destroy_segment

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Date:	Wed, 06 Nov 2013 13:15:36 +0800
From:	Gu Zheng <guz.fnst@...fujitsu.com>
To:	Chao Yu <chao2.yu@...sung.com>
CC:	"'???'" <jaegeuk.kim@...sung.com>, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net,
	'谭姝' <shu.tan@...sung.com>
Subject: Re: [f2fs-dev] [PATCH] f2fs: avoid to use a NULL point in destroy_segment_manager

On 11/06/2013 01:10 PM, Chao Yu wrote:

> Hi Gu,
> 
>> -----Original Message-----
>> From: Gu Zheng [mailto:guz.fnst@...fujitsu.com]
>> Sent: Wednesday, November 06, 2013 11:41 AM
>> To: Chao Yu
>> Cc: ???; linux-fsdevel@...r.kernel.org; linux-kernel@...r.kernel.org; linux-f2fs-devel@...ts.sourceforge.net; 谭姝
>> Subject: Re: [f2fs-dev] [PATCH] f2fs: avoid to use a NULL point in destroy_segment_manager
>>
>> On 11/06/2013 09:12 AM, Chao Yu wrote:
>>
>>> A NULL point should avoid to be used in destroy_segment_manager after allocating memory fail for f2fs_sm_info.
>>
>> Though without this patch it still can work well, because if it failed
>> to allocate f2fs_sm_info, the sit_info, free_info... all were NULL, and
>> the destory path(e.g. destroy_dirty_segmap) can deal with them well.
> 
> I think it could not work well. Without this patch we may got a segment 
> fault in DIRTY_I(sbi) at the following code if it failed to allocate 
> f2fs_sm_info memory(sbi->sm_info). Right?

Yes, you're right. SIT_I generates sit_info from f2fs_sm_info.
Sorry for my mistake.:(

Regards,
Gu

> 
> static void destroy_dirty_segmap(struct f2fs_sb_info *sbi)
> {
> 	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
> 
>> IMO, this patch is still a good catch.
>>
>> Regards,
>> Gu
>>
>>>
>>> Signed-off-by: Chao Yu <chao2.yu@...sung.com>
>>> ---
>>>  fs/f2fs/segment.c |    2 ++
>>>  1 file changed, 2 insertions(+)
>>>
>>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>>> index 3d4d5fc..ff363e6
>>> --- a/fs/f2fs/segment.c
>>> +++ b/fs/f2fs/segment.c
>>> @@ -1744,6 +1744,8 @@ static void destroy_sit_info(struct f2fs_sb_info *sbi)
>>>  void destroy_segment_manager(struct f2fs_sb_info *sbi)
>>>  {
>>>  	struct f2fs_sm_info *sm_info = SM_I(sbi);
>>> +	if (!sm_info)
>>> +		return;
>>>  	destroy_dirty_segmap(sbi);
>>>  	destroy_curseg(sbi);
>>>  	destroy_free_segmap(sbi);
> 
> 
> 


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