linux-kernel - Re: [PATCH] sysv: use BUILD_BUG

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Date:   Mon, 27 Sep 2021 15:12:42 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     dhowells@...hat.com, viro@...iv.linux.org.uk,
        akpm@...ux-foundation.org
Cc:     linux-kernel@...r.kernel.org, hch@...radead.org
Subject: Re: [PATCH] sysv: use BUILD_BUG_ON instead of runtime check

On 9/1/21 13:15, Pavel Skripkin wrote:
> On 8/13/21 15:30, Pavel Skripkin wrote:
>> There was runtime checks about sizes of struct v7_super_block
>> and struct sysv_inode. If one of these checks fail kernel will panic.
>> Since these values are known on complite time let's use BUILD_BUG_ON(),
>> because it's standard mechanism for validation checking at build time
>> 
>> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
>> Signed-off-by: Pavel Skripkin <paskripkin@...il.com>
>> ---
>>   fs/sysv/super.c | 6 ++----
>>   1 file changed, 2 insertions(+), 4 deletions(-)
>> 
>> diff --git a/fs/sysv/super.c b/fs/sysv/super.c
>> index cc8e2ed155c8..d1def0771a40 100644
>> --- a/fs/sysv/super.c
>> +++ b/fs/sysv/super.c
>> @@ -474,10 +474,8 @@ static int v7_fill_super(struct super_block *sb, void *data, int silent)
>>   	struct sysv_sb_info *sbi;
>>   	struct buffer_head *bh;
>>   
>> -	if (440 != sizeof (struct v7_super_block))
>> -		panic("V7 FS: bad super-block size");
>> -	if (64 != sizeof (struct sysv_inode))
>> -		panic("sysv fs: bad i-node size");
>> +	BUILD_BUG_ON(sizeof(struct v7_super_block) != 440);
>> +	BUILD_BUG_ON(sizeof(struct sysv_inode) != 64);
>>   
>>   	sbi = kzalloc(sizeof(struct sysv_sb_info), GFP_KERNEL);
>>   	if (!sbi)
>> 
> 
> Hi, David and Alexander!
> 
> 
> Maybe, this one can go through one of your trees? I didn't find any sysv
> related trees, so..
> 
> Lore link to the patch:
> https://lore.kernel.org/lkml/20210813123020.22971-1-paskripkin@gmail.com/
> 
> 
> 
> Thank you!


Hi, Andrew,

Maybe this one can go through your tree?



With regards,
Pavel Skripkin