linux-kernel - RE: [PATCH 1/7 5.10.y] tracing: Define the is_signed

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Message-ID: <91da8ce3e4fb4a8991876a3ed130a873@amazon.com>
Date: Wed, 17 Sep 2025 10:37:31 +0000
From: "Farber, Eliav" <farbere@...zon.com>
To: Greg KH <gregkh@...uxfoundation.org>
CC: "luc.vanoostenryck@...il.com" <luc.vanoostenryck@...il.com>,
	"rostedt@...dmis.org" <rostedt@...dmis.org>, "mingo@...hat.com"
	<mingo@...hat.com>, "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"sj@...nel.org" <sj@...nel.org>, "David.Laight@...lab.com"
	<David.Laight@...lab.com>, "Jason@...c4.com" <Jason@...c4.com>,
	"andriy.shevchenko@...ux.intel.com" <andriy.shevchenko@...ux.intel.com>,
	"bvanassche@....org" <bvanassche@....org>, "keescook@...omium.org"
	<keescook@...omium.org>, "linux-sparse@...r.kernel.org"
	<linux-sparse@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "Chocron, Jonathan" <jonnyc@...zon.com>,
	"stable@...r.kernel.org" <stable@...r.kernel.org>, Rasmus Villemoes
	<linux@...musvillemoes.dk>, "Farber, Eliav" <farbere@...zon.com>
Subject: RE: [PATCH 1/7 5.10.y] tracing: Define the is_signed_type() macro
 once

> On Tue, Sep 16, 2025 at 09:22:53PM +0000, Eliav Farber wrote:
> > From: Bart Van Assche <bvanassche@....org>
> >
> > commit 92d23c6e94157739b997cacce151586a0d07bb8a upstream.
>
> This is only in 6.1, and not other trees, why is it needed here?

It exists also in 5.15:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/include/linux/overflow.h?h=v5.15.193&id=ed6e37e30826b12572636c6bbfe6319233690c90

Without this change, I get many compilation errors when backporting
commit d53b5d862acd ("minmax: allow min()/max()/clamp() if the
arguments have the same signedness.")

  CALL    scripts/atomic/check-atomics.sh
  CC      arch/arm64/kernel/asm-offsets.s
In file included from ./include/linux/bits.h:22,
                 from ./include/linux/ioport.h:15,
                 from ./include/linux/acpi.h:12,
                 from ./include/acpi/apei.h:9,
                 from ./include/acpi/ghes.h:5,
                 from ./include/linux/arm_sdei.h:8,
                 from arch/arm64/kernel/asm-offsets.c:10:
./include/linux/nodemask.h: In function '__first_node':
./include/linux/minmax.h:30:39: error: implicit declaration of function 'is_signed_type' [-Werror=implicit-function-declaration]
   30 |  __builtin_choose_expr(__is_constexpr(is_signed_type(typeof(x))), \
      |                                       ^~~~~~~~~~~~~~
./include/linux/build_bug.h:78:56: note: in definition of macro '__static_assert'
   78 | #define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
      |                                                        ^~~~
./include/linux/minmax.h:50:3: note: in expansion of macro 'static_assert'
   50 |   static_assert(__types_ok(x, y),  \
      |   ^~~~~~~~~~~~~
./include/linux/minmax.h:30:24: note: in expansion of macro '__is_constexpr'
   30 |  __builtin_choose_expr(__is_constexpr(is_signed_type(typeof(x))), \
      |                        ^~~~~~~~~~~~~~
./include/linux/minmax.h:38:3: note: in expansion of macro '__is_signed'
   38 |  (__is_signed(x) == __is_signed(y) ||   \
      |   ^~~~~~~~~~~
./include/linux/minmax.h:50:17: note: in expansion of macro '__types_ok'
   50 |   static_assert(__types_ok(x, y),  \
      |                 ^~~~~~~~~~
./include/linux/minmax.h:57:3: note: in expansion of macro '__cmp_once'
   57 |   __cmp_once(op, x, y, __UNIQUE_ID(__x), __UNIQUE_ID(__y)))
      |   ^~~~~~~~~~
./include/linux/minmax.h:160:27: note: in expansion of macro '__careful_cmp'
  160 | #define min_t(type, x, y) __careful_cmp(min, (type)(x), (type)(y))
      |                           ^~~~~~~~~~~~~
./include/linux/nodemask.h:265:9: note: in expansion of macro 'min_t'
  265 |  return min_t(unsigned int, MAX_NUMNODES, find_first_bit(srcp->bits, MAX_NUMNODES));
      |         ^~~~~
./include/linux/minmax.h:30:54: error: expected expression before 'typeof'
   30 |  __builtin_choose_expr(__is_constexpr(is_signed_type(typeof(x))), \
      |                                                      ^~~~~~
./include/linux/build_bug.h:78:56: note: in definition of macro '__static_assert'
...


> > Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org> (cherry 
> > picked from commit a49a64b5bf195381c09202c524f0f84b5f3e816f)
>
> This is not a valid git id in the tree at all.

I will fix the mismatch here and above, but please notice that this
hash appears in the link I shared.

---
Regards, Eliav