drivers/infiniband/hw/qib/qib_sysfs.c:413:1: error: static_assert expression is not an integral constant expression
10:17 p.m.
tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 926de8c4326c14fcf35f1de142019043597a4fac
commit: 84f969e1c48ed3825986e91a0786e363d57f69d1 IB/qib: Fix null pointer subtraction
compiler warning
date: 3 days ago
config: x86_64-randconfig-a014-20210911 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project
261cbe98c38f8c1ee1a482fe76511110e790f58a)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O
~/bin/make.cross
chmod +x ~/bin/make.cross
#
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit...
git remote add linus
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
git fetch --no-tags linus master
git checkout 84f969e1c48ed3825986e91a0786e363d57f69d1
# save the attached .config to linux build tree
mkdir build_dir
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross O=build_dir ARCH=x86_64
SHELL=/bin/bash
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp(a)intel.com>
All errors (new ones prefixed by >>):
> 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);
\
~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:77:50: note: expanded from macro 'static_assert'
#define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr)
~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:78:56: note: expanded from macro '__static_assert'
#define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
^~~~
drivers/infiniband/hw/qib/qib_sysfs.c:413:1: note: cannot access field of null pointer
drivers/infiniband/hw/qib/qib_sysfs.c:406:43: note: expanded from macro
'QIB_DIAGC_ATTR'
static_assert(&((struct qib_ibport *)0)->rvp.n_##N != (u64 *)NULL);
\
^
drivers/infiniband/hw/qib/qib_sysfs.c:414:1: error: static_assert expression is not an
integral constant expression
QIB_DIAGC_ATTR(seq_naks);
^~~~~~~~~~~~~~~~~~~~~~~~
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);
\
~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:77:50: note: expanded from macro 'static_assert'
#define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr)
~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:78:56: note: expanded from macro '__static_assert'
#define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
^~~~
drivers/infiniband/hw/qib/qib_sysfs.c:414:1: note: cannot access field of null pointer
drivers/infiniband/hw/qib/qib_sysfs.c:406:43: note: expanded from macro
'QIB_DIAGC_ATTR'
static_assert(&((struct qib_ibport *)0)->rvp.n_##N != (u64 *)NULL);
\
^
drivers/infiniband/hw/qib/qib_sysfs.c:415:1: error: static_assert expression is not an
integral constant expression
QIB_DIAGC_ATTR(rdma_seq);
^~~~~~~~~~~~~~~~~~~~~~~~
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);
\
~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:77:50: note: expanded from macro 'static_assert'
#define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr)
~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:78:56: note: expanded from macro '__static_assert'
#define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
^~~~
drivers/infiniband/hw/qib/qib_sysfs.c:415:1: note: cannot access field of null pointer
drivers/infiniband/hw/qib/qib_sysfs.c:406:43: note: expanded from macro
'QIB_DIAGC_ATTR'
static_assert(&((struct qib_ibport *)0)->rvp.n_##N != (u64 *)NULL);
\
^
drivers/infiniband/hw/qib/qib_sysfs.c:416:1: error: static_assert expression is not an
integral constant expression
QIB_DIAGC_ATTR(rnr_naks);
^~~~~~~~~~~~~~~~~~~~~~~~
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);
\
~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:77:50: note: expanded from macro 'static_assert'
#define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr)
~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:78:56: note: expanded from macro '__static_assert'
#define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
^~~~
drivers/infiniband/hw/qib/qib_sysfs.c:416:1: note: cannot access field of null pointer
drivers/infiniband/hw/qib/qib_sysfs.c:406:43: note: expanded from macro
'QIB_DIAGC_ATTR'
static_assert(&((struct qib_ibport *)0)->rvp.n_##N != (u64 *)NULL);
\
^
drivers/infiniband/hw/qib/qib_sysfs.c:417:1: error: static_assert expression is not an
integral constant expression
QIB_DIAGC_ATTR(other_naks);
^~~~~~~~~~~~~~~~~~~~~~~~~~
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);
\
~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:77:50: note: expanded from macro 'static_assert'
#define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr)
~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:78:56: note: expanded from macro '__static_assert'
#define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
^~~~
drivers/infiniband/hw/qib/qib_sysfs.c:417:1: note: cannot access field of null pointer
drivers/infiniband/hw/qib/qib_sysfs.c:406:43: note: expanded from macro
'QIB_DIAGC_ATTR'
static_assert(&((struct qib_ibport *)0)->rvp.n_##N != (u64 *)NULL);
\
^
drivers/infiniband/hw/qib/qib_sysfs.c:418:1: error: static_assert expression is not an
integral constant expression
QIB_DIAGC_ATTR(rc_timeouts);
^~~~~~~~~~~~~~~~~~~~~~~~~~~
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);
\
~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:77:50: note: expanded from macro 'static_assert'
#define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr)
~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:78:56: note: expanded from macro '__static_assert'
#define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
^~~~
drivers/infiniband/hw/qib/qib_sysfs.c:418:1: note: cannot access field of null pointer
drivers/infiniband/hw/qib/qib_sysfs.c:406:43: note: expanded from macro
'QIB_DIAGC_ATTR'
static_assert(&((struct qib_ibport *)0)->rvp.n_##N != (u64 *)NULL);
\
^
drivers/infiniband/hw/qib/qib_sysfs.c:419:1: error: static_assert expression is not an
integral constant expression
QIB_DIAGC_ATTR(loop_pkts);
^~~~~~~~~~~~~~~~~~~~~~~~~
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);
\
vim +413 drivers/infiniband/hw/qib/qib_sysfs.c
f24a6d4887668c Harish Chegondi 2016-01-22 404
4a7aaf88c89f12 Jason Gunthorpe 2021-06-11 405 #define QIB_DIAGC_ATTR(N)
\
84f969e1c48ed3 Jason Gunthorpe 2021-09-03 406 static_assert(&((struct qib_ibport
*)0)->rvp.n_##N != (u64 *)NULL); \
f24a6d4887668c Harish Chegondi 2016-01-22 407 static struct qib_diagc_attr
qib_diagc_attr_##N = { \
4a7aaf88c89f12 Jason Gunthorpe 2021-06-11 408 .attr = __ATTR(N, 0664, diagc_attr_show,
diagc_attr_store), \
84f969e1c48ed3 Jason Gunthorpe 2021-09-03 409 .counter =
\
84f969e1c48ed3 Jason Gunthorpe 2021-09-03 410 offsetof(struct qib_ibport, rvp.n_##N)
/ sizeof(u64) \
f931551bafe1f1 Ralph Campbell 2010-05-23 411 }
f931551bafe1f1 Ralph Campbell 2010-05-23 412
f931551bafe1f1 Ralph Campbell 2010-05-23 @413 QIB_DIAGC_ATTR(rc_resends);
f931551bafe1f1 Ralph Campbell 2010-05-23 414 QIB_DIAGC_ATTR(seq_naks);
f931551bafe1f1 Ralph Campbell 2010-05-23 415 QIB_DIAGC_ATTR(rdma_seq);
f931551bafe1f1 Ralph Campbell 2010-05-23 416 QIB_DIAGC_ATTR(rnr_naks);
f931551bafe1f1 Ralph Campbell 2010-05-23 417 QIB_DIAGC_ATTR(other_naks);
f931551bafe1f1 Ralph Campbell 2010-05-23 418 QIB_DIAGC_ATTR(rc_timeouts);
f931551bafe1f1 Ralph Campbell 2010-05-23 419 QIB_DIAGC_ATTR(loop_pkts);
f931551bafe1f1 Ralph Campbell 2010-05-23 420 QIB_DIAGC_ATTR(pkt_drops);
f931551bafe1f1 Ralph Campbell 2010-05-23 421 QIB_DIAGC_ATTR(dmawait);
f931551bafe1f1 Ralph Campbell 2010-05-23 422 QIB_DIAGC_ATTR(unaligned);
f931551bafe1f1 Ralph Campbell 2010-05-23 423 QIB_DIAGC_ATTR(rc_dupreq);
f931551bafe1f1 Ralph Campbell 2010-05-23 424 QIB_DIAGC_ATTR(rc_seqnak);
7199435414868b Kaike Wan 2019-09-11 425 QIB_DIAGC_ATTR(rc_crwaits);
f931551bafe1f1 Ralph Campbell 2010-05-23 426
:::::: The code at line 413 was first introduced by commit
:::::: f931551bafe1f10ded7f5282e2aa162c267a2e5d IB/qib: Add new qib driver for QLogic PCIe
InfiniBand adapters
:::::: TO: Ralph Campbell <ralph.campbell(a)qlogic.com>
:::::: CC: Roland Dreier <rolandd(a)cisco.com>
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
2:53 a.m.
On Sat, Sep 11, 2021 at 08:17:08PM +0800, kernel test robot wrote:
tree:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 926de8c4326c14fcf35f1de142019043597a4fac
commit: 84f969e1c48ed3825986e91a0786e363d57f69d1 IB/qib: Fix null pointer subtraction
compiler warning
date: 3 days ago
config: x86_64-randconfig-a014-20210911 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project
261cbe98c38f8c1ee1a482fe76511110e790f58a)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O
~/bin/make.cross
chmod +x ~/bin/make.cross
#
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit...
git remote add linus
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
git fetch --no-tags linus master
git checkout 84f969e1c48ed3825986e91a0786e363d57f69d1
# save the attached .config to linux build tree
mkdir build_dir
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross O=build_dir
ARCH=x86_64 SHELL=/bin/bash
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp(a)intel.com>
All errors (new ones prefixed by >>):
>> 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);
\
~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:77:50: note: expanded from macro 'static_assert'
#define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr)
~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:78:56: note: expanded from macro '__static_assert'
#define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
^~~~
drivers/infiniband/hw/qib/qib_sysfs.c:413:1: note: cannot access field of null
pointer
drivers/infiniband/hw/qib/qib_sysfs.c:406:43: note: expanded from macro
'QIB_DIAGC_ATTR'
static_assert(&((struct qib_ibport *)0)->rvp.n_##N != (u64 *)NULL);
\
^
drivers/infiniband/hw/qib/qib_sysfs.c:414:1: error: static_assert expression is not an
integral constant expression
QIB_DIAGC_ATTR(seq_naks);
^~~~~~~~~~~~~~~~~~~~~~~~
Nick/Nathan
Clang is being a real PITA here - do you know of a solution?
This macro would like to know that the passed in member name has a u64
type, all the things I've come up with fail on clang - but many work
fine on gcc. Frankly I think this case is a clang bug myself..
Thanks,
Jason
3 a.m.
On Mon, Sep 13, 2021 at 9:53 AM Jason Gunthorpe <jgg(a)nvidia.com> wrote:
On Sat, Sep 11, 2021 at 08:17:08PM +0800, kernel test robot wrote:
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head: 926de8c4326c14fcf35f1de142019043597a4fac
> commit: 84f969e1c48ed3825986e91a0786e363d57f69d1 IB/qib: Fix null pointer
subtraction compiler warning
> date: 3 days ago
> config: x86_64-randconfig-a014-20210911 (attached as .config)
> compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project
261cbe98c38f8c1ee1a482fe76511110e790f58a)
> reproduce (this is a W=1 build):
> wget
https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O
~/bin/make.cross
> chmod +x ~/bin/make.cross
> #
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit...
> git remote add linus
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> git fetch --no-tags linus master
> git checkout 84f969e1c48ed3825986e91a0786e363d57f69d1
> # save the attached .config to linux build tree
> mkdir build_dir
> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross O=build_dir
ARCH=x86_64 SHELL=/bin/bash
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp(a)intel.com>
>
> All errors (new ones prefixed by >>):
>
> >> 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); \
> ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> include/linux/build_bug.h:77:50: note: expanded from macro
'static_assert'
> #define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr)
> ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
> include/linux/build_bug.h:78:56: note: expanded from macro
'__static_assert'
> #define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
> ^~~~
> drivers/infiniband/hw/qib/qib_sysfs.c:413:1: note: cannot access field of null
pointer
> drivers/infiniband/hw/qib/qib_sysfs.c:406:43: note: expanded from macro
'QIB_DIAGC_ATTR'
> static_assert(&((struct qib_ibport *)0)->rvp.n_##N != (u64
*)NULL); \
> ^
> drivers/infiniband/hw/qib/qib_sysfs.c:414:1: error: static_assert expression is
not an integral constant expression
> QIB_DIAGC_ATTR(seq_naks);
> ^~~~~~~~~~~~~~~~~~~~~~~~
Nick/Nathan
Clang is being a real PITA here - do you know of a solution?
Hi Jason,
Thanks for wrestling with this. We filed a quick thread last week to
track this:
https://github.com/ClangBuiltLinux/linux/issues/1452
With conferences this and next week, and -Werror fallout, there's a
lot of fire right now and not a lot of time to triage.
I guess I'm curious, what is the intent of what this code is trying to
do, and can this be replaced with BUILD_BUG_ON?
This macro would like to know that the passed in member name has a u64
type, all the things I've come up with fail on clang - but many work
fine on gcc. Frankly I think this case is a clang bug myself..
Perhaps, though this assertion looks a bit like offsetof() to me. I
wonder if that can help here?
--
Thanks,
~Nick Desaulniers
4:38 a.m.
On Mon, Sep 13, 2021 at 10:00:02AM -0700, Nick Desaulniers wrote:
> This macro would like to know that the passed in member name has
a u64
> type, all the things I've come up with fail on clang - but many work
> fine on gcc. Frankly I think this case is a clang bug myself..
Perhaps, though this assertion looks a bit like offsetof() to me. I
wonder if that can help here?
The assertion would logically like to be this:
static_assert(typecheck(((struct qib_port *)0)->N, u64))
Which doesn't compile because typecheck is not a constexpr :\
typecheck also can't be used as a build bug on zero in the initializer
for the same reason.
My original attempt was
.counter = &((struct qib_ibport *)0)->rvp.n_##N - (u64 *)0, \
Which is fairly simple opencoding of offsetof_end but clang whines
overly pedantically that NULL subtraction is undefined behavior.
The current version is this:
static_assert(&((struct qib_ibport *)0)->rvp.n_##N != (u64 *)NULL);
Which *should* be perfectly fine, but clang explodes for some reason
complaining about -> on NULL. I think it is broken and doesn't
understand that this -> is not an actual deref but pointer/type logic,
much like this:
#define sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER))
Which does work.
So to my mind clang is being buggy, and I'm probably going to just
delete the line and a give up on type checking here unless someone has
a better idea.
Jason
4:53 a.m.
On Mon, Sep 13, 2021 at 03:38:13PM -0300, Jason Gunthorpe wrote:
On Mon, Sep 13, 2021 at 10:00:02AM -0700, Nick Desaulniers wrote:
> > This macro would like to know that the passed in member name has a u64
> > type, all the things I've come up with fail on clang - but many work
> > fine on gcc. Frankly I think this case is a clang bug myself..
>
> Perhaps, though this assertion looks a bit like offsetof() to me. I
> wonder if that can help here?
The assertion would logically like to be this:
static_assert(typecheck(((struct qib_port *)0)->N, u64))
This works for me with both GCC and clang, if that is acceptable to you?
It fails if you change one of the variables to 'u32'.
Cheers,
Nathan
diff --git a/drivers/infiniband/hw/qib/qib_sysfs.c
b/drivers/infiniband/hw/qib/qib_sysfs.c
index 452e2355d24e..0a3b28142c05 100644
--- a/drivers/infiniband/hw/qib/qib_sysfs.c
+++ b/drivers/infiniband/hw/qib/qib_sysfs.c
@@ -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 = \
5:02 a.m.
On Mon, Sep 13, 2021 at 11:53:25AM -0700, Nathan Chancellor wrote:
On Mon, Sep 13, 2021 at 03:38:13PM -0300, Jason Gunthorpe wrote:
> On Mon, Sep 13, 2021 at 10:00:02AM -0700, Nick Desaulniers wrote:
>
> > > This macro would like to know that the passed in member name has a u64
> > > type, all the things I've come up with fail on clang - but many work
> > > fine on gcc. Frankly I think this case is a clang bug myself..
> >
> > Perhaps, though this assertion looks a bit like offsetof() to me. I
> > wonder if that can help here?
>
> The assertion would logically like to be this:
>
> static_assert(typecheck(((struct qib_port *)0)->N, u64))
This works for me with both GCC and clang, if that is acceptable to you?
It fails if you change one of the variables to 'u32'.
Yes, thanks. Can't say I've even heard of __same_type before :\ would
be nice if this was in typecheck.h along with the other variations of
the same idea. Presumably it is a little bit different from those
somehow?
Jason
5:13 a.m.
On 9/13/2021 12:02 PM, Jason Gunthorpe wrote:
On Mon, Sep 13, 2021 at 11:53:25AM -0700, Nathan Chancellor wrote:
> On Mon, Sep 13, 2021 at 03:38:13PM -0300, Jason Gunthorpe wrote:
>> On Mon, Sep 13, 2021 at 10:00:02AM -0700, Nick Desaulniers wrote:
>>
>>>> This macro would like to know that the passed in member name has a u64
>>>> type, all the things I've come up with fail on clang - but many work
>>>> fine on gcc. Frankly I think this case is a clang bug myself..
>>>
>>> Perhaps, though this assertion looks a bit like offsetof() to me. I
>>> wonder if that can help here?
>>
>> The assertion would logically like to be this:
>>
>> static_assert(typecheck(((struct qib_port *)0)->N, u64))
>
> This works for me with both GCC and clang, if that is acceptable to you?
> It fails if you change one of the variables to 'u32'.
Yes, thanks. Can't say I've even heard of __same_type before :\ would
be nice if this was in typecheck.h along with the other variations of
the same idea. Presumably it is a little bit different from those
somehow?
Good question... commit d2c123c27db8 ("module_param: add __same_type
convenience wrapper for __builtin_types_compatible_p") introduced it so
that it could be used in commit fddd52012295 ("module_param: allow
'bool' module_params to be bool, not just int."); I am guessing that
typecheck() could not be used in those cases. Perhaps all instances of
typecheck() could be converted to __same_type()?
Do you want me to send a formal patch for that diff?
Cheers,
Nathan
5:16 a.m.
On Mon, Sep 13, 2021 at 12:13:45PM -0700, Nathan Chancellor wrote:
On 9/13/2021 12:02 PM, Jason Gunthorpe wrote:
> On Mon, Sep 13, 2021 at 11:53:25AM -0700, Nathan Chancellor wrote:
> > On Mon, Sep 13, 2021 at 03:38:13PM -0300, Jason Gunthorpe wrote:
> > > On Mon, Sep 13, 2021 at 10:00:02AM -0700, Nick Desaulniers wrote:
> > >
> > > > > This macro would like to know that the passed in member name has
a u64
> > > > > type, all the things I've come up with fail on clang - but
many work
> > > > > fine on gcc. Frankly I think this case is a clang bug myself..
> > > >
> > > > Perhaps, though this assertion looks a bit like offsetof() to me. I
> > > > wonder if that can help here?
> > >
> > > The assertion would logically like to be this:
> > >
> > > static_assert(typecheck(((struct qib_port *)0)->N, u64))
> >
> > This works for me with both GCC and clang, if that is acceptable to you?
> > It fails if you change one of the variables to 'u32'.
>
> Yes, thanks. Can't say I've even heard of __same_type before :\ would
> be nice if this was in typecheck.h along with the other variations of
> the same idea. Presumably it is a little bit different from those
> somehow?
Good question... commit d2c123c27db8 ("module_param: add __same_type
convenience wrapper for __builtin_types_compatible_p") introduced it so that
it could be used in commit fddd52012295 ("module_param: allow 'bool'
module_params to be bool, not just int."); I am guessing that typecheck()
could not be used in those cases. Perhaps all instances of typecheck() could
be converted to __same_type()?
Do you want me to send a formal patch for that diff?
I think it is a reasonable thing to do if it works, but I do wonder if
they are not quite the same thing considering qualifiers/etc
$ git grep typecheck | wc -l
120
$ #git grep __same_type | wc -l
39
I would delete __same_type if typecheck can be functionally identical
otherwise I'd say this should all be in typecheck.h and the functional
difference clearly documented..
Jason
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Jason Gunthorpe -
kernel test robot -
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Nick Desaulniers