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@xxxxxxxxx> >> --- >> 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>