lkml.org 
[lkml]   [2013]   [Dec]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] mm/zswap.c: add BUG() for default case in zswap_writeback_entry()
On 12/09/2013 05:54 PM, James Hogan wrote:
> On 09/12/13 02:51, Chen Gang wrote:
>> Recommend to add default case to avoid compiler's warning, although at
>> present, the original implementation is still correct.
>>
>> The related warning (with allmodconfig for metag):
>>
>> CC mm/zswap.o
>> mm/zswap.c: In function 'zswap_writeback_entry':
>> mm/zswap.c:537: warning: 'ret' may be used uninitialized in this function
>>
>>
>> Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
>> ---
>> mm/zswap.c | 2 ++
>> 1 files changed, 2 insertions(+), 0 deletions(-)
>>
>> diff --git a/mm/zswap.c b/mm/zswap.c
>> index 5a63f78..bfd1807 100644
>> --- a/mm/zswap.c
>> +++ b/mm/zswap.c
>> @@ -585,6 +585,8 @@ static int zswap_writeback_entry(struct zbud_pool *pool, unsigned long handle)
>>
>> /* page is up to date */
>> SetPageUptodate(page);
>> + default:
>> + BUG();
>
> This doesn't hide the warning when CONFIG_BUG=n since BUG() optimises
> out completely.
>

When "CONFIG_BUG=n", it will report many related warnings (for me,
CONFIG_BUG need be as architecture specific config feature, not a
generic config feature -- most architectures always enable it).

So for common generic users, we can assume it will always have effect.


> Since the metag compiler is stuck on an old version (gcc 4.2.4), which
> is wrong to warn in this case, and newer versions of gcc don't appear to
> warn about it anyway (I just checked with gcc 4.7.2 x86_64), I have no
> objection to this warning remaining in the metag build.
>

Do you try "EXTRA_CFLAGS=-W" with gcc 4.7.2? I guess it will report the
warning too, I don't feel the compiler is smart enough (except it lets
the long function zswap_get_swap_cache_page really inline) :-)


Thanks.
--
Chen Gang

Open, share, and attitude like air, water and life which God blessed


\
 
 \ /
  Last update: 2013-12-09 11:41    [W:0.082 / U:0.236 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site