Re: [PATCH rc] IB/qib: Fix clang confusion of NULL pointer comparison
flat view
From: Nick Desaulniers <ndesaulniers@google.com>
Date: 2021-09-14 19:18:50
Also in:
linux-rdma
On Tue, Sep 14, 2021 at 12:01 PM Jason Gunthorpe [off-list ref] wrote:
clang becomes confused due to the comparision to NULL in a contexpr context:
s/comparision/comparison/ s/contexpr/Integer Constant Expression/ I don't think constexpr is the equivalent to an ICE. We know what you mean though. :^)
>> drivers/infiniband/hw/qib/qib_sysfs.c:413:1: error: static_assert expression is not an integral constant expression
QIB_DIAGC_ATTR(rc_resends);
^~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/infiniband/hw/qib/qib_sysfs.c:406:16: note: expanded from macro 'QIB_DIAGC_ATTR'
static_assert(&((struct qib_ibport *)0)->rvp.n_##N != (u64 *)NULL); \
Nick found __same_type that solves this problem nicely, so use it instead.Sorry, Nathan found that. Should be: Suggested-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Thanks for the patch.
Reported-by: kernel test robot <redacted> Suggested-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> --- drivers/infiniband/hw/qib/qib_sysfs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Hopefully third time is the charm here..
:^)
quoted hunk
diff --git a/drivers/infiniband/hw/qib/qib_sysfs.c b/drivers/infiniband/hw/qib/qib_sysfs.c index 452e2355d24eeb..0a3b28142c05b6 100644 --- a/drivers/infiniband/hw/qib/qib_sysfs.c +++ b/drivers/infiniband/hw/qib/qib_sysfs.c
Consider explicitly including <linux/compiler_types.h> in this translation unit. I know it may compile today, and it might just be our internal style guide talking here...
quoted hunk
@@ -403,7 +403,7 @@ static ssize_t diagc_attr_store(struct ib_device *ibdev, u32 port_num, } #define QIB_DIAGC_ATTR(N) \ - static_assert(&((struct qib_ibport *)0)->rvp.n_##N != (u64 *)NULL); \ + static_assert(__same_type(((struct qib_ibport *)0)->rvp.n_##N, u64)); \ static struct qib_diagc_attr qib_diagc_attr_##N = { \ .attr = __ATTR(N, 0664, diagc_attr_show, diagc_attr_store), \ .counter = \base-commit: 6880fa6c56601bb8ed59df6c30fd390cc5f6dd8f -- 2.33.0
-- Thanks, ~Nick Desaulniers