Re: [PATCH v2 1/2] xfs: Fix compiler warning in xfs_attr_node_removename_setup

[Allison Collins <allison.henderson@oracle.com>]

On 7/27/20 11:50 AM, Darrick J. Wong wrote:
> On Mon, Jul 27, 2020 at 09:51:54AM -0700, Allison Collins wrote:
>>
>>
>> On 7/27/20 8:46 AM, Darrick J. Wong wrote:
>>> On Sun, Jul 26, 2020 at 07:26:07PM -0700, Allison Collins wrote:
>>>> Fix compiler warning for variable 'blk' set but not used in
>>>> xfs_attr_node_removename_setup.  blk is used only in an ASSERT so only
>>>> declare blk when DEBUG is set.
>>>>
>>>> Reported-by: kernel test robot <lkp@intel.com>
>>>> Signed-off-by: Allison Collins <allison.henderson@oracle.com>
>>>> ---
>>>>    fs/xfs/libxfs/xfs_attr.c | 2 ++
>>>>    1 file changed, 2 insertions(+)
>>>>
>>>> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
>>>> index d4583a0..5168d32 100644
>>>> --- a/fs/xfs/libxfs/xfs_attr.c
>>>> +++ b/fs/xfs/libxfs/xfs_attr.c
>>>> @@ -1174,7 +1174,9 @@ int xfs_attr_node_removename_setup(
>>>>    	struct xfs_da_state	**state)
>>>>    {
>>>>    	int			error;
>>>> +#ifdef DEBUG
>>>>    	struct xfs_da_state_blk	*blk;
>>>> +#endif
>>>
>>> But now a non-DEBUG compilation will trip over the assignment to blk:
>>>
>>> 	blk = &(*state)->path.blk[(*state)->path.active - 1];
>>>
>>> that comes just before the asserts, right?
>>>
>>> 	ASSERT((*state)->path.blk[(*state)->path.active - 1].bp != NULL);
>>> 	ASSERT((*state)->path.blk[(*state)->path.active - 1].magic ==
>>> 		XFS_ATTR_LEAF_MAGIC);
>>>
>>> In the end you probably just want to encode the accessor logic in the
>>> assert body so the whole thing just disappears entirely.
>> Are you sure you'd rather have it that way, then once up in the declaration?
>> Like this:
>>
>> #ifdef DEBUG
>> 	struct xfs_da_state_blk	*blk = &(*state)->path.blk[(*state)->path.active -
>> 1];
>> #endif
> 
> I thought xfs_attr_node_hasname could allocate the da state and set
> *state, which means that we can't dereference *state until after that
> call?
I see, ok then, will add the deference in the asserts

Allison

> 
> --D
> 
>>>
>>> --D
>>>
>>>>    	error = xfs_attr_node_hasname(args, state);
>>>>    	if (error != -EEXIST)
>>>> -- 
>>>> 2.7.4
>>>>