On 23/06/2020 14:55, Rikard Falkeborn wrote:
Den tis 23 juni 2020 12:21John Garry <john.ga...@huawei.com
<mailto:john.ga...@huawei.com>> skrev:
On 23/06/2020 10:35, Rikard Falkeborn wrote:
>
> I'd say that GENMASK_INPUT_CHECK() should be able to handle a
l=0 and
> h=unsigned value, so I doubt this warn.
>
> Using GENMASK((int)cmdq->q.llq.max_n_shift, 0) resolves it,
but it
> looks
> like GENMASK_INPUT_CHECK() could be improved.
>
>
> Indeed it could, it is fixed in -next.
ok, thanks for the pointer, but I still see this on today's -next with
this patch:
make W=1 drivers/iommu/arm-smmu-v3.o
Oh, ok thanks for reporting. I guess different gcc versions have
different behaviour. I guess we'll have to change the comparison to
(!((h) == (l) || (h) > (l))) instead (not sure I got all parenthesis and
logic correct but you get the idea).
Yeah, so this looks to fix it:
--- a/include/linux/bits.h
+++ b/include/linux/bits.h
@@ -23,7 +23,8 @@
#include <linux/build_bug.h>
#define GENMASK_INPUT_CHECK(h, l) \
(BUILD_BUG_ON_ZERO(__builtin_choose_expr( \
- __builtin_constant_p((l) > (h)), (l) > (h), 0)))
+ __builtin_constant_p(!((h) == (l) ||(h) > (l))), !((h)
== (l) ||(h) > (l)), 0)))
+
We may be able to just use (h) == (l) as the const expr to make it more
concise, but that may be confusing.
I only tested with my toolchain based on 7.5.0
Thanks,
John
