From: David Laight <david.laight.linux@gmail.com>
-Wshadow is enabled by W=2 builds and __scoped_user_access() quite
deliberately creates a 'const' shadow of the 'user' address that
references a 'guard page' when the application passes a kernel pointer.
Signed-off-by: David Laight <david.laight.linux@gmail.com>
---
include/linux/uaccess.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 64bc2492eb99..445391ec5a6d 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -739,7 +739,9 @@ static __always_inline void __scoped_user_rw_access_end(const void *p)
#define __scoped_user_access(mode, uptr, size, elbl) \
with (auto _tmpptr = __scoped_user_access_begin(mode, uptr, size, elbl)) \
/* Force modified pointer usage within the scope */ \
- and_with (const auto uptr __cleanup(__scoped_user_##mode##_access_end) = _tmpptr)
+ __diag_push() __diag_ignore_all("-Wshadow", "uptr is readonly copy") \
+ and_with (const auto uptr __cleanup(__scoped_user_##mode##_access_end) = _tmpptr) \
+ __diag_pop()
/**
* scoped_user_read_access_size - Start a scoped user read access with given size
--
2.39.5Hi,
kernel test robot noticed the following build errors:
[auto build test ERROR on brauner-vfs/vfs.all]
[also build test ERROR on v7.0-rc2]
[cannot apply to linus/master next-20260303]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/david-laight-linux-gmail-com/uaccess-Fix-scoped_user_read_access-for-pointer-to-const/20260302-213317
base: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git vfs.all
patch link: https://lore.kernel.org/r/20260302132755.1475451-5-david.laight.linux%40gmail.com
patch subject: [PATCH v2 4/5] uaccess: Disable -Wshadow in __scoped_user_access()
config: nios2-allnoconfig (https://download.01.org/0day-ci/archive/20260305/202603051642.i46zzlJ8-lkp@intel.com/config)
compiler: nios2-linux-gcc (GCC) 11.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260305/202603051642.i46zzlJ8-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202603051642.i46zzlJ8-lkp@intel.com/
All error/warnings (new ones prefixed by >>):
In file included from include/asm-generic/div64.h:27,
from ./arch/nios2/include/generated/asm/div64.h:1,
from include/linux/math.h:6,
from include/linux/math64.h:6,
from include/linux/time.h:6,
from include/linux/compat.h:10,
from kernel/futex/core.c:34:
kernel/futex/futex.h: In function 'futex_get_value_locked':
>> include/linux/uaccess.h:740:20: warning: unused variable '_tmpptr' [-Wunused-variable]
740 | with (auto _tmpptr = __scoped_user_access_begin(mode, uptr, size, elbl)) \
| ^~~~~~~
include/linux/compiler.h:396:14: note: in definition of macro 'and_with'
396 | for (declaration; !_with_done; _with_done = true)
| ^~~~~~~~~~~
include/linux/uaccess.h:740:9: note: in expansion of macro 'with'
740 | with (auto _tmpptr = __scoped_user_access_begin(mode, uptr, size, elbl)) \
| ^~~~
include/linux/uaccess.h:755:9: note: in expansion of macro '__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:767:9: note: in expansion of macro 'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:831:9: note: in expansion of macro 'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/futex.h:288:16: note: in expansion of macro 'get_user_inline'
288 | return get_user_inline(*dest, from);
| ^~~~~~~~~~~~~~~
>> include/linux/compiler.h:396:9: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
396 | for (declaration; !_with_done; _with_done = true)
| ^~~
include/linux/compiler.h:394:17: note: in expansion of macro 'and_with'
394 | and_with (declaration)
| ^~~~~~~~
include/linux/uaccess.h:740:9: note: in expansion of macro 'with'
740 | with (auto _tmpptr = __scoped_user_access_begin(mode, uptr, size, elbl)) \
| ^~~~
include/linux/uaccess.h:755:9: note: in expansion of macro '__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:767:9: note: in expansion of macro 'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:831:9: note: in expansion of macro 'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/futex.h:288:16: note: in expansion of macro 'get_user_inline'
288 | return get_user_inline(*dest, from);
| ^~~~~~~~~~~~~~~
In file included from include/linux/compiler_types.h:173,
from <command-line>:
include/linux/compiler-gcc.h:118:33: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
118 | #define __diag(s) _Pragma(__diag_str(GCC diagnostic s))
| ^~~~~~~
include/linux/compiler-gcc.h:129:9: note: in expansion of macro '__diag'
129 | __diag(__diag_GCC_ignore option)
| ^~~~~~
include/linux/uaccess.h:742:31: note: in expansion of macro '__diag_ignore_all'
742 | __diag_push() __diag_ignore_all("-Wshadow", "uptr is readonly copy") \
| ^~~~~~~~~~~~~~~~~
include/linux/uaccess.h:755:9: note: in expansion of macro '__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:767:9: note: in expansion of macro 'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:831:9: note: in expansion of macro 'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/futex.h:288:16: note: in expansion of macro 'get_user_inline'
288 | return get_user_inline(*dest, from);
| ^~~~~~~~~~~~~~~
In file included from include/asm-generic/div64.h:27,
from ./arch/nios2/include/generated/asm/div64.h:1,
from include/linux/math.h:6,
from include/linux/math64.h:6,
from include/linux/time.h:6,
from include/linux/compat.h:10,
from kernel/futex/core.c:34:
>> include/linux/uaccess.h:743:90: error: '_tmpptr' undeclared (first use in this function)
743 | and_with (const auto uptr __cleanup(__scoped_user_##mode##_access_end) = _tmpptr) \
| ^~~~~~~
include/linux/compiler.h:396:14: note: in definition of macro 'and_with'
396 | for (declaration; !_with_done; _with_done = true)
| ^~~~~~~~~~~
include/linux/uaccess.h:755:9: note: in expansion of macro '__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:767:9: note: in expansion of macro 'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:831:9: note: in expansion of macro 'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/futex.h:288:16: note: in expansion of macro 'get_user_inline'
288 | return get_user_inline(*dest, from);
| ^~~~~~~~~~~~~~~
include/linux/uaccess.h:743:90: note: each undeclared identifier is reported only once for each function it appears in
743 | and_with (const auto uptr __cleanup(__scoped_user_##mode##_access_end) = _tmpptr) \
| ^~~~~~~
include/linux/compiler.h:396:14: note: in definition of macro 'and_with'
396 | for (declaration; !_with_done; _with_done = true)
| ^~~~~~~~~~~
include/linux/uaccess.h:755:9: note: in expansion of macro '__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:767:9: note: in expansion of macro 'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:831:9: note: in expansion of macro 'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/futex.h:288:16: note: in expansion of macro 'get_user_inline'
288 | return get_user_inline(*dest, from);
| ^~~~~~~~~~~~~~~
>> include/linux/compiler.h:396:28: error: '_with_done' undeclared (first use in this function)
396 | for (declaration; !_with_done; _with_done = true)
| ^~~~~~~~~~
include/linux/uaccess.h:743:17: note: in expansion of macro 'and_with'
743 | and_with (const auto uptr __cleanup(__scoped_user_##mode##_access_end) = _tmpptr) \
| ^~~~~~~~
include/linux/uaccess.h:755:9: note: in expansion of macro '__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:767:9: note: in expansion of macro 'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:831:9: note: in expansion of macro 'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/futex.h:288:16: note: in expansion of macro 'get_user_inline'
288 | return get_user_inline(*dest, from);
| ^~~~~~~~~~~~~~~
kernel/futex/core.c: In function 'get_futex_key':
>> include/linux/uaccess.h:740:20: warning: unused variable '_tmpptr' [-Wunused-variable]
740 | with (auto _tmpptr = __scoped_user_access_begin(mode, uptr, size, elbl)) \
| ^~~~~~~
include/linux/compiler.h:396:14: note: in definition of macro 'and_with'
396 | for (declaration; !_with_done; _with_done = true)
| ^~~~~~~~~~~
include/linux/uaccess.h:740:9: note: in expansion of macro 'with'
740 | with (auto _tmpptr = __scoped_user_access_begin(mode, uptr, size, elbl)) \
| ^~~~
include/linux/uaccess.h:755:9: note: in expansion of macro '__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:767:9: note: in expansion of macro 'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:831:9: note: in expansion of macro 'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/core.c:584:21: note: in expansion of macro 'get_user_inline'
584 | if (get_user_inline(node, naddr))
| ^~~~~~~~~~~~~~~
>> include/linux/compiler.h:396:9: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
396 | for (declaration; !_with_done; _with_done = true)
| ^~~
include/linux/compiler.h:394:17: note: in expansion of macro 'and_with'
394 | and_with (declaration)
| ^~~~~~~~
include/linux/uaccess.h:740:9: note: in expansion of macro 'with'
740 | with (auto _tmpptr = __scoped_user_access_begin(mode, uptr, size, elbl)) \
| ^~~~
include/linux/uaccess.h:755:9: note: in expansion of macro '__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:767:9: note: in expansion of macro 'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:831:9: note: in expansion of macro 'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/core.c:584:21: note: in expansion of macro 'get_user_inline'
584 | if (get_user_inline(node, naddr))
| ^~~~~~~~~~~~~~~
In file included from include/linux/compiler_types.h:173,
from <command-line>:
include/linux/compiler-gcc.h:118:33: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
118 | #define __diag(s) _Pragma(__diag_str(GCC diagnostic s))
| ^~~~~~~
include/linux/compiler-gcc.h:129:9: note: in expansion of macro '__diag'
129 | __diag(__diag_GCC_ignore option)
| ^~~~~~
include/linux/uaccess.h:742:31: note: in expansion of macro '__diag_ignore_all'
742 | __diag_push() __diag_ignore_all("-Wshadow", "uptr is readonly copy") \
| ^~~~~~~~~~~~~~~~~
include/linux/uaccess.h:755:9: note: in expansion of macro '__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:767:9: note: in expansion of macro 'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:831:9: note: in expansion of macro 'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/core.c:584:21: note: in expansion of macro 'get_user_inline'
584 | if (get_user_inline(node, naddr))
| ^~~~~~~~~~~~~~~
In file included from include/asm-generic/div64.h:27,
from ./arch/nios2/include/generated/asm/div64.h:1,
from include/linux/math.h:6,
from include/linux/math64.h:6,
from include/linux/time.h:6,
from include/linux/compat.h:10,
from kernel/futex/core.c:34:
>> include/linux/uaccess.h:743:90: error: '_tmpptr' undeclared (first use in this function)
743 | and_with (const auto uptr __cleanup(__scoped_user_##mode##_access_end) = _tmpptr) \
| ^~~~~~~
include/linux/compiler.h:396:14: note: in definition of macro 'and_with'
396 | for (declaration; !_with_done; _with_done = true)
| ^~~~~~~~~~~
include/linux/uaccess.h:755:9: note: in expansion of macro '__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:767:9: note: in expansion of macro 'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:831:9: note: in expansion of macro 'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/core.c:584:21: note: in expansion of macro 'get_user_inline'
584 | if (get_user_inline(node, naddr))
| ^~~~~~~~~~~~~~~
>> include/linux/compiler.h:396:28: error: '_with_done' undeclared (first use in this function)
396 | for (declaration; !_with_done; _with_done = true)
| ^~~~~~~~~~
include/linux/uaccess.h:743:17: note: in expansion of macro 'and_with'
743 | and_with (const auto uptr __cleanup(__scoped_user_##mode##_access_end) = _tmpptr) \
| ^~~~~~~~
include/linux/uaccess.h:755:9: note: in expansion of macro '__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:767:9: note: in expansion of macro 'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:831:9: note: in expansion of macro 'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/core.c:584:21: note: in expansion of macro 'get_user_inline'
584 | if (get_user_inline(node, naddr))
| ^~~~~~~~~~~~~~~
>> include/linux/uaccess.h:740:20: warning: unused variable '_tmpptr' [-Wunused-variable]
740 | with (auto _tmpptr = __scoped_user_access_begin(mode, uptr, size, elbl)) \
| ^~~~~~~
include/linux/compiler.h:396:14: note: in definition of macro 'and_with'
396 | for (declaration; !_with_done; _with_done = true)
| ^~~~~~~~~~~
include/linux/uaccess.h:740:9: note: in expansion of macro 'with'
740 | with (auto _tmpptr = __scoped_user_access_begin(mode, uptr, size, elbl)) \
| ^~~~
include/linux/uaccess.h:778:9: note: in expansion of macro '__scoped_user_access'
778 | __scoped_user_access(write, udst, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:790:9: note: in expansion of macro 'scoped_user_write_access_size'
790 | scoped_user_write_access_size(udst, sizeof(*(udst)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:856:9: note: in expansion of macro 'scoped_user_write_access'
856 | scoped_user_write_access(_tmpdst, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/core.c:604:37: note: in expansion of macro 'put_user_inline'
604 | if (node_updated && put_user_inline(node, naddr))
| ^~~~~~~~~~~~~~~
>> include/linux/compiler.h:396:9: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
396 | for (declaration; !_with_done; _with_done = true)
| ^~~
include/linux/compiler.h:394:17: note: in expansion of macro 'and_with'
394 | and_with (declaration)
| ^~~~~~~~
include/linux/uaccess.h:740:9: note: in expansion of macro 'with'
740 | with (auto _tmpptr = __scoped_user_access_begin(mode, uptr, size, elbl)) \
| ^~~~
include/linux/uaccess.h:778:9: note: in expansion of macro '__scoped_user_access'
778 | __scoped_user_access(write, udst, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:790:9: note: in expansion of macro 'scoped_user_write_access_size'
790 | scoped_user_write_access_size(udst, sizeof(*(udst)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:856:9: note: in expansion of macro 'scoped_user_write_access'
856 | scoped_user_write_access(_tmpdst, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/core.c:604:37: note: in expansion of macro 'put_user_inline'
604 | if (node_updated && put_user_inline(node, naddr))
| ^~~~~~~~~~~~~~~
In file included from include/linux/compiler_types.h:173,
from <command-line>:
include/linux/compiler-gcc.h:118:33: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
118 | #define __diag(s) _Pragma(__diag_str(GCC diagnostic s))
| ^~~~~~~
include/linux/compiler-gcc.h:129:9: note: in expansion of macro '__diag'
129 | __diag(__diag_GCC_ignore option)
| ^~~~~~
include/linux/uaccess.h:742:31: note: in expansion of macro '__diag_ignore_all'
742 | __diag_push() __diag_ignore_all("-Wshadow", "uptr is readonly copy") \
| ^~~~~~~~~~~~~~~~~
include/linux/uaccess.h:778:9: note: in expansion of macro '__scoped_user_access'
778 | __scoped_user_access(write, udst, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:790:9: note: in expansion of macro 'scoped_user_write_access_size'
790 | scoped_user_write_access_size(udst, sizeof(*(udst)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/uaccess.h:856:9: note: in expansion of macro 'scoped_user_write_access'
856 | scoped_user_write_access(_tmpdst, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/core.c:604:37: note: in expansion of macro 'put_user_inline'
604 | if (node_updated && put_user_inline(node, naddr))
| ^~~~~~~~~~~~~~~
..
vim +/_tmpptr +743 include/linux/uaccess.h
689
690 /**
691 * __scoped_user_access - Open a scope for user access
692 * @mode: The mode of the access class (read, write, rw)
693 * @uptr: The pointer to access user space memory
694 * @size: Size of the access
695 * @elbl: Error label to goto when the access region is rejected. It
696 * must be placed outside the scope
697 *
698 * If the user access function inside the scope requires a fault label, it
699 * can use @elbl or a different label outside the scope, which requires
700 * that user access which is implemented with ASM GOTO has been properly
701 * wrapped. See unsafe_get_user() for reference.
702 *
703 * scoped_user_rw_access(ptr, efault) {
704 * unsafe_get_user(rval, &ptr->rval, efault);
705 * unsafe_put_user(wval, &ptr->wval, efault);
706 * }
707 * return 0;
708 * efault:
709 * return -EFAULT;
710 *
711 * The scope is internally implemented as a autoterminating nested for()
712 * loop, which can be left with 'return', 'break' and 'goto' at any
713 * point.
714 *
715 * When the scope is left user_##@_mode##_access_end() is automatically
716 * invoked.
717 *
718 * When the architecture supports masked user access and the access region
719 * which is determined by @uptr and @size is not a valid user space
720 * address, i.e. < TASK_SIZE, the scope sets the pointer to a faulting user
721 * space address and does not terminate early. This optimizes for the good
722 * case and lets the performance uncritical bad case go through the fault.
723 *
724 * The eventual modification of the pointer is limited to the scope.
725 * Outside of the scope the original pointer value is unmodified, so that
726 * the original pointer value is available for diagnostic purposes in an
727 * out of scope fault path.
728 *
729 * Nesting scoped user access into a user access scope is invalid and fails
730 * the build. Nesting into other guards, e.g. pagefault is safe.
731 *
732 * The masked variant does not check the size of the access and relies on a
733 * mapping hole (e.g. guard page) to catch an out of range pointer, the
734 * first access to user memory inside the scope has to be within
735 * @uptr ... @uptr + PAGE_SIZE - 1
736 *
737 * Don't use directly. Use scoped_masked_user_$MODE_access() instead.
738 */
739 #define __scoped_user_access(mode, uptr, size, elbl) \
> 740 with (auto _tmpptr = __scoped_user_access_begin(mode, uptr, size, elbl)) \
741 /* Force modified pointer usage within the scope */ \
742 __diag_push() __diag_ignore_all("-Wshadow", "uptr is readonly copy") \
> 743 and_with (const auto uptr __cleanup(__scoped_user_##mode##_access_end) = _tmpptr) \
744 __diag_pop()
745
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
On Mon, 2 Mar 2026 at 05:28, <david.laight.linux@gmail.com> wrote:
>
> From: David Laight <david.laight.linux@gmail.com>
>
> -Wshadow is enabled by W=2 builds and __scoped_user_access() quite
> deliberately creates a 'const' shadow of the 'user' address that
> references a 'guard page' when the application passes a kernel pointer.
This is too ugly to live.
There is no way that we should make an already unreadable macro even
worse just because somebody - incorrectly - thinks that W=2 matters.
No - what matters a whole lot more is keeping the kernel sources
readable (well, at least as readable as is possible).
Because W=2 is one of those "you get what you deserve" things.
Linus
Le 02/03/2026 à 14:27, david.laight.linux@gmail.com a écrit :
> From: David Laight <david.laight.linux@gmail.com>
>
> -Wshadow is enabled by W=2 builds and __scoped_user_access() quite
> deliberately creates a 'const' shadow of the 'user' address that
> references a 'guard page' when the application passes a kernel pointer.
>
> Signed-off-by: David Laight <david.laight.linux@gmail.com>
There is a problem with this patch:
DESCEND objtool
INSTALL libsubcmd_headers
CALL scripts/checksyscalls.sh
CC kernel/futex/core.o
In file included from ./include/asm-generic/div64.h:27,
from ./arch/powerpc/include/generated/asm/div64.h:1,
from ./include/linux/math.h:6,
from ./include/linux/math64.h:6,
from ./include/linux/time.h:6,
from ./include/linux/compat.h:10,
from kernel/futex/core.c:34:
kernel/futex/futex.h: In function 'futex_get_value_locked':
./include/linux/uaccess.h:740:20: warning: unused variable '_tmpptr'
[-Wunused-variable]
740 | with (auto _tmpptr = __scoped_user_access_begin(mode,
uptr, size, elbl)) \
| ^~~~~~~
./include/linux/compiler.h:396:14: note: in definition of macro 'and_with'
396 | for (declaration; !_with_done; _with_done = true)
| ^~~~~~~~~~~
./include/linux/uaccess.h:740:9: note: in expansion of macro 'with'
740 | with (auto _tmpptr = __scoped_user_access_begin(mode,
uptr, size, elbl)) \
| ^~~~
./include/linux/uaccess.h:755:9: note: in expansion of macro
'__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:767:9: note: in expansion of macro
'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:831:9: note: in expansion of macro
'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/futex.h:288:16: note: in expansion of macro 'get_user_inline'
288 | return get_user_inline(*dest, from);
| ^~~~~~~~~~~~~~~
./include/linux/compiler.h:396:9: warning: this 'for' clause does not
guard... [-Wmisleading-indentation]
396 | for (declaration; !_with_done; _with_done = true)
| ^~~
./include/linux/compiler.h:394:17: note: in expansion of macro 'and_with'
394 | and_with (declaration)
| ^~~~~~~~
./include/linux/uaccess.h:740:9: note: in expansion of macro 'with'
740 | with (auto _tmpptr = __scoped_user_access_begin(mode,
uptr, size, elbl)) \
| ^~~~
./include/linux/uaccess.h:755:9: note: in expansion of macro
'__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:767:9: note: in expansion of macro
'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:831:9: note: in expansion of macro
'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/futex.h:288:16: note: in expansion of macro 'get_user_inline'
288 | return get_user_inline(*dest, from);
| ^~~~~~~~~~~~~~~
In file included from ././include/linux/compiler_types.h:173,
from <command-line>:
./include/linux/compiler-gcc.h:118:33: note: ...this statement, but the
latter is misleadingly indented as if it were guarded by the 'for'
118 | #define __diag(s) _Pragma(__diag_str(GCC
diagnostic s))
| ^~~~~~~
./include/linux/compiler-gcc.h:129:9: note: in expansion of macro '__diag'
129 | __diag(__diag_GCC_ignore option)
| ^~~~~~
./include/linux/uaccess.h:742:31: note: in expansion of macro
'__diag_ignore_all'
742 | __diag_push() __diag_ignore_all("-Wshadow",
"uptr is readonly copy") \
| ^~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:755:9: note: in expansion of macro
'__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:767:9: note: in expansion of macro
'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:831:9: note: in expansion of macro
'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/futex.h:288:16: note: in expansion of macro 'get_user_inline'
288 | return get_user_inline(*dest, from);
| ^~~~~~~~~~~~~~~
In file included from ./include/asm-generic/div64.h:27,
from ./arch/powerpc/include/generated/asm/div64.h:1,
from ./include/linux/math.h:6,
from ./include/linux/math64.h:6,
from ./include/linux/time.h:6,
from ./include/linux/compat.h:10,
from kernel/futex/core.c:34:
./include/linux/uaccess.h:743:90: error: '_tmpptr' undeclared (first use
in this function)
743 | and_with (const auto uptr
__cleanup(__scoped_user_##mode##_access_end) = _tmpptr) \
|
^~~~~~~
./include/linux/compiler.h:396:14: note: in definition of macro 'and_with'
396 | for (declaration; !_with_done; _with_done = true)
| ^~~~~~~~~~~
./include/linux/uaccess.h:755:9: note: in expansion of macro
'__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:767:9: note: in expansion of macro
'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:831:9: note: in expansion of macro
'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/futex.h:288:16: note: in expansion of macro 'get_user_inline'
288 | return get_user_inline(*dest, from);
| ^~~~~~~~~~~~~~~
./include/linux/uaccess.h:743:90: note: each undeclared identifier is
reported only once for each function it appears in
743 | and_with (const auto uptr
__cleanup(__scoped_user_##mode##_access_end) = _tmpptr) \
|
^~~~~~~
./include/linux/compiler.h:396:14: note: in definition of macro 'and_with'
396 | for (declaration; !_with_done; _with_done = true)
| ^~~~~~~~~~~
./include/linux/uaccess.h:755:9: note: in expansion of macro
'__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:767:9: note: in expansion of macro
'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:831:9: note: in expansion of macro
'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/futex.h:288:16: note: in expansion of macro 'get_user_inline'
288 | return get_user_inline(*dest, from);
| ^~~~~~~~~~~~~~~
./include/linux/compiler.h:396:28: error: '_with_done' undeclared (first
use in this function)
396 | for (declaration; !_with_done; _with_done = true)
| ^~~~~~~~~~
./include/linux/uaccess.h:743:17: note: in expansion of macro 'and_with'
743 | and_with (const auto uptr
__cleanup(__scoped_user_##mode##_access_end) = _tmpptr) \
| ^~~~~~~~
./include/linux/uaccess.h:755:9: note: in expansion of macro
'__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:767:9: note: in expansion of macro
'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:831:9: note: in expansion of macro
'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/futex.h:288:16: note: in expansion of macro 'get_user_inline'
288 | return get_user_inline(*dest, from);
| ^~~~~~~~~~~~~~~
kernel/futex/core.c: In function 'get_futex_key':
./include/linux/uaccess.h:740:20: warning: unused variable '_tmpptr'
[-Wunused-variable]
740 | with (auto _tmpptr = __scoped_user_access_begin(mode,
uptr, size, elbl)) \
| ^~~~~~~
./include/linux/compiler.h:396:14: note: in definition of macro 'and_with'
396 | for (declaration; !_with_done; _with_done = true)
| ^~~~~~~~~~~
./include/linux/uaccess.h:740:9: note: in expansion of macro 'with'
740 | with (auto _tmpptr = __scoped_user_access_begin(mode,
uptr, size, elbl)) \
| ^~~~
./include/linux/uaccess.h:755:9: note: in expansion of macro
'__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:767:9: note: in expansion of macro
'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:831:9: note: in expansion of macro
'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/core.c:584:21: note: in expansion of macro 'get_user_inline'
584 | if (get_user_inline(node, naddr))
| ^~~~~~~~~~~~~~~
./include/linux/compiler.h:396:9: warning: this 'for' clause does not
guard... [-Wmisleading-indentation]
396 | for (declaration; !_with_done; _with_done = true)
| ^~~
./include/linux/compiler.h:394:17: note: in expansion of macro 'and_with'
394 | and_with (declaration)
| ^~~~~~~~
./include/linux/uaccess.h:740:9: note: in expansion of macro 'with'
740 | with (auto _tmpptr = __scoped_user_access_begin(mode,
uptr, size, elbl)) \
| ^~~~
./include/linux/uaccess.h:755:9: note: in expansion of macro
'__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:767:9: note: in expansion of macro
'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:831:9: note: in expansion of macro
'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/core.c:584:21: note: in expansion of macro 'get_user_inline'
584 | if (get_user_inline(node, naddr))
| ^~~~~~~~~~~~~~~
In file included from ././include/linux/compiler_types.h:173,
from <command-line>:
./include/linux/compiler-gcc.h:118:33: note: ...this statement, but the
latter is misleadingly indented as if it were guarded by the 'for'
118 | #define __diag(s) _Pragma(__diag_str(GCC
diagnostic s))
| ^~~~~~~
./include/linux/compiler-gcc.h:129:9: note: in expansion of macro '__diag'
129 | __diag(__diag_GCC_ignore option)
| ^~~~~~
./include/linux/uaccess.h:742:31: note: in expansion of macro
'__diag_ignore_all'
742 | __diag_push() __diag_ignore_all("-Wshadow",
"uptr is readonly copy") \
| ^~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:755:9: note: in expansion of macro
'__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:767:9: note: in expansion of macro
'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:831:9: note: in expansion of macro
'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/core.c:584:21: note: in expansion of macro 'get_user_inline'
584 | if (get_user_inline(node, naddr))
| ^~~~~~~~~~~~~~~
In file included from ./include/asm-generic/div64.h:27,
from ./arch/powerpc/include/generated/asm/div64.h:1,
from ./include/linux/math.h:6,
from ./include/linux/math64.h:6,
from ./include/linux/time.h:6,
from ./include/linux/compat.h:10,
from kernel/futex/core.c:34:
./include/linux/uaccess.h:743:90: error: '_tmpptr' undeclared (first use
in this function)
743 | and_with (const auto uptr
__cleanup(__scoped_user_##mode##_access_end) = _tmpptr) \
|
^~~~~~~
./include/linux/compiler.h:396:14: note: in definition of macro 'and_with'
396 | for (declaration; !_with_done; _with_done = true)
| ^~~~~~~~~~~
./include/linux/uaccess.h:755:9: note: in expansion of macro
'__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:767:9: note: in expansion of macro
'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:831:9: note: in expansion of macro
'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/core.c:584:21: note: in expansion of macro 'get_user_inline'
584 | if (get_user_inline(node, naddr))
| ^~~~~~~~~~~~~~~
./include/linux/compiler.h:396:28: error: '_with_done' undeclared (first
use in this function)
396 | for (declaration; !_with_done; _with_done = true)
| ^~~~~~~~~~
./include/linux/uaccess.h:743:17: note: in expansion of macro 'and_with'
743 | and_with (const auto uptr
__cleanup(__scoped_user_##mode##_access_end) = _tmpptr) \
| ^~~~~~~~
./include/linux/uaccess.h:755:9: note: in expansion of macro
'__scoped_user_access'
755 | __scoped_user_access(read, usrc, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:767:9: note: in expansion of macro
'scoped_user_read_access_size'
767 | scoped_user_read_access_size(usrc, sizeof(*(usrc)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:831:9: note: in expansion of macro
'scoped_user_read_access'
831 | scoped_user_read_access(_tmpsrc, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/core.c:584:21: note: in expansion of macro 'get_user_inline'
584 | if (get_user_inline(node, naddr))
| ^~~~~~~~~~~~~~~
./include/linux/uaccess.h:740:20: warning: unused variable '_tmpptr'
[-Wunused-variable]
740 | with (auto _tmpptr = __scoped_user_access_begin(mode,
uptr, size, elbl)) \
| ^~~~~~~
./include/linux/compiler.h:396:14: note: in definition of macro 'and_with'
396 | for (declaration; !_with_done; _with_done = true)
| ^~~~~~~~~~~
./include/linux/uaccess.h:740:9: note: in expansion of macro 'with'
740 | with (auto _tmpptr = __scoped_user_access_begin(mode,
uptr, size, elbl)) \
| ^~~~
./include/linux/uaccess.h:778:9: note: in expansion of macro
'__scoped_user_access'
778 | __scoped_user_access(write, udst, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:790:9: note: in expansion of macro
'scoped_user_write_access_size'
790 | scoped_user_write_access_size(udst, sizeof(*(udst)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:856:9: note: in expansion of macro
'scoped_user_write_access'
856 | scoped_user_write_access(_tmpdst, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/core.c:604:37: note: in expansion of macro 'put_user_inline'
604 | if (node_updated && put_user_inline(node, naddr))
| ^~~~~~~~~~~~~~~
./include/linux/compiler.h:396:9: warning: this 'for' clause does not
guard... [-Wmisleading-indentation]
396 | for (declaration; !_with_done; _with_done = true)
| ^~~
./include/linux/compiler.h:394:17: note: in expansion of macro 'and_with'
394 | and_with (declaration)
| ^~~~~~~~
./include/linux/uaccess.h:740:9: note: in expansion of macro 'with'
740 | with (auto _tmpptr = __scoped_user_access_begin(mode,
uptr, size, elbl)) \
| ^~~~
./include/linux/uaccess.h:778:9: note: in expansion of macro
'__scoped_user_access'
778 | __scoped_user_access(write, udst, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:790:9: note: in expansion of macro
'scoped_user_write_access_size'
790 | scoped_user_write_access_size(udst, sizeof(*(udst)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:856:9: note: in expansion of macro
'scoped_user_write_access'
856 | scoped_user_write_access(_tmpdst, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/core.c:604:37: note: in expansion of macro 'put_user_inline'
604 | if (node_updated && put_user_inline(node, naddr))
| ^~~~~~~~~~~~~~~
In file included from ././include/linux/compiler_types.h:173,
from <command-line>:
./include/linux/compiler-gcc.h:118:33: note: ...this statement, but the
latter is misleadingly indented as if it were guarded by the 'for'
118 | #define __diag(s) _Pragma(__diag_str(GCC
diagnostic s))
| ^~~~~~~
./include/linux/compiler-gcc.h:129:9: note: in expansion of macro '__diag'
129 | __diag(__diag_GCC_ignore option)
| ^~~~~~
./include/linux/uaccess.h:742:31: note: in expansion of macro
'__diag_ignore_all'
742 | __diag_push() __diag_ignore_all("-Wshadow",
"uptr is readonly copy") \
| ^~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:778:9: note: in expansion of macro
'__scoped_user_access'
778 | __scoped_user_access(write, udst, size, elbl)
| ^~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:790:9: note: in expansion of macro
'scoped_user_write_access_size'
790 | scoped_user_write_access_size(udst, sizeof(*(udst)), elbl)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/uaccess.h:856:9: note: in expansion of macro
'scoped_user_write_access'
856 | scoped_user_write_access(_tmpdst, efault) \
| ^~~~~~~~~~~~~~~~~~~~~~~~
kernel/futex/core.c:604:37: note: in expansion of macro 'put_user_inline'
604 | if (node_updated && put_user_inline(node, naddr))
| ^~~~~~~~~~~~~~~
make[4]: *** [scripts/Makefile.build:289: kernel/futex/core.o] Error 1
make[3]: *** [scripts/Makefile.build:546: kernel/futex] Error 2
make[2]: *** [scripts/Makefile.build:546: kernel] Error 2
make[1]: *** [/home/chleroy/linux-powerpc/Makefile:2101: .] Error 2
make: *** [Makefile:248: __sub-make] Error 2
> ---
> include/linux/uaccess.h | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
> index 64bc2492eb99..445391ec5a6d 100644
> --- a/include/linux/uaccess.h
> +++ b/include/linux/uaccess.h
> @@ -739,7 +739,9 @@ static __always_inline void __scoped_user_rw_access_end(const void *p)
> #define __scoped_user_access(mode, uptr, size, elbl) \
> with (auto _tmpptr = __scoped_user_access_begin(mode, uptr, size, elbl)) \
> /* Force modified pointer usage within the scope */ \
> - and_with (const auto uptr __cleanup(__scoped_user_##mode##_access_end) = _tmpptr)
> + __diag_push() __diag_ignore_all("-Wshadow", "uptr is readonly copy") \
> + and_with (const auto uptr __cleanup(__scoped_user_##mode##_access_end) = _tmpptr) \
> + __diag_pop()
>
> /**
> * scoped_user_read_access_size - Start a scoped user read access with given size
On Mon, 2 Mar 2026 16:00:26 +0100 "Christophe Leroy (CS GROUP)" <chleroy@kernel.org> wrote: > Le 02/03/2026 à 14:27, david.laight.linux@gmail.com a écrit : > > From: David Laight <david.laight.linux@gmail.com> > > > > -Wshadow is enabled by W=2 builds and __scoped_user_access() quite > > deliberately creates a 'const' shadow of the 'user' address that > > references a 'guard page' when the application passes a kernel pointer. > > > > Signed-off-by: David Laight <david.laight.linux@gmail.com> > > There is a problem with this patch: (badly line-wrapped errors deleted) It seems to need gcc 12. (So Linus is in luck.) Prior to gcc 12 the #pragma generated by _Pragma() act as the controlled statement of the for () loop. Trying to put the _Pragma() inside the for statement doesn't work at all. David
© 2016 - 2026 Red Hat, Inc.