On 10/10/2023 18:00, Andrew Cooper wrote:
On 10/10/2023 9:02 am, Stefano Stabellini wrote:
On Fri, 6 Oct 2023, Nicola Vetrini wrote:
The essential type of the result of an inequality operator is
essentially boolean, therefore it shouldn't be used as an argument of
the multiplication operator, which expects an integer.
Signed-off-by: Nicola Vetrini <nicola.vetr...@bugseng.com>
---
xen/include/xen/compat.h | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/xen/include/xen/compat.h b/xen/include/xen/compat.h
index f2ce5bb3580a..5ffee6a9fed1 100644
--- a/xen/include/xen/compat.h
+++ b/xen/include/xen/compat.h
@@ -151,12 +151,14 @@ CHECK_NAME_(k, n, T)(k xen_ ## n *x, \
return x == c; \
}
+#define SIZE_NEQUAL(a, b) \
+ (sizeof(a) != sizeof(b) ? 1 : 0)
#define CHECK_SIZE(name) \
- typedef int CHECK_NAME(name, S)[1 - (sizeof(xen_ ## name ## _t)
!= \
- sizeof(compat_ ## name ##
_t)) * 2]
+ typedef int CHECK_NAME(name, S)[1 - (SIZE_NEQUAL(xen_ ## name ##
_t, \
+ compat_ ## name
## _t)) * 2]
#define CHECK_SIZE_(k, n) \
- typedef int CHECK_NAME_(k, n, S)[1 - (sizeof(k xen_ ## n) != \
- sizeof(k compat_ ## n)) *
2]
+ typedef int CHECK_NAME_(k, n, S)[1 - (SIZE_NEQUAL(k xen_ ## n, \
+ k compat_ ##
n)) * 2]
I think this style is easier to read but I'll let the x86 maintainers
decide
typedef int CHECK_NAME(name, S)[(sizeof(xen_ ## name ## _t) == \
sizeof(compat_ ## name ## _t)) ?
1 : -1]
Also am I reading this correctly that we are using -1 as array index?
I
must have made a calculation mistake?
This is a NIH BUILD_BUG_ON(). It should be rewritten as
BUILD_BUG_ON(sizeof(xen ...) != sizeof(compat ...));
which will use _Static_assert() in modern compilers.
~Andrew
Ok, thanks.
--
Nicola Vetrini, BSc
Software Engineer, BUGSENG srl (https://bugseng.com)
