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SubjectRe: [PATCH -next 2/2] bcache: Use max_t() when comparing different types
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On Mon, Feb 3, 2014 at 2:47 PM, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> On Wed, Jan 15, 2014 at 12:06 PM, Joe Perches <joe@perches.com> wrote:
>> On Wed, 2014-01-15 at 10:06 +0100, Geert Uytterhoeven wrote:
>>> drivers/md/bcache/btree.c: In function ‘insert_u64s_remaining’:
>>> drivers/md/bcache/btree.c:1816: warning: comparison of distinct pointer types lacks a cast
>> []
>>> diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
>> []
>>> @@ -1813,7 +1813,7 @@ static size_t insert_u64s_remaining(struct btree *b)
>>> if (b->keys.ops->is_extents)
>>> ret -= KEY_MAX_U64S;
>>>
>>> - return max(ret, 0L);
>>> + return max_t(ssize_t, ret, 0L);
>>
>> why not
>> return max(ret, 0);
>
> Indeed, that also works, on both 32-bit and 64-bit.
> Will resend, now all the issues moved from -next to Linus' tree.

However, sparse doesn't like it, so we'll have to go for v1?

From kbuild test robot fengguang.wu@intel.com:

>> drivers/md/bcache/btree.c:1816:16: sparse: incompatible types in comparison expression (different type sizes)
In file included from arch/x86/include/asm/percpu.h:44:0,
from arch/x86/include/asm/preempt.h:5,
from include/linux/preempt.h:18,
from include/linux/spinlock.h:50,
from include/linux/wait.h:8,
from include/linux/fs.h:6,
from include/linux/highmem.h:4,
from include/linux/bio.h:23,
from drivers/md/bcache/bcache.h:181,
from drivers/md/bcache/btree.c:23:
drivers/md/bcache/btree.c: In function 'insert_u64s_remaining':
include/linux/kernel.h:718:17: warning: comparison of distinct
pointer types lacks a cast [enabled by default]
(void) (&_max1 == &_max2); \
^
drivers/md/bcache/btree.c:1816:9: note: in expansion of macro 'max'
return max(ret, 0);
^

vim +1816 drivers/md/bcache/btree.c

1800 status);
1801 return true;
1802 } else
1803 return false;
1804 }
1805
1806 static size_t insert_u64s_remaining(struct btree *b)
1807 {
1808 ssize_t ret = bch_btree_keys_u64s_remaining(&b->keys);
1809
1810 /*
1811 * Might land in the middle of an existing extent and
have to split it
1812 */
1813 if (b->keys.ops->is_extents)
1814 ret -= KEY_MAX_U64S;
1815
> 1816 return max(ret, 0);
1817 }
1818
1819 static bool bch_btree_insert_keys(struct btree *b, struct btree_op *op,
1820 struct keylist *insert_keys,
1821 struct bkey *replace_key)
1822 {
1823 bool ret = false;
1824 int oldsize = bch_count_data(&b->keys);

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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