From: kernel test robot <lkp@intel.com>
To: david.laight.linux@gmail.com,
Alexander Viro <viro@zeniv.linux.org.uk>,
Andre Almeida <andrealmeid@igalia.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Christian Brauner <brauner@kernel.org>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
"Christophe Leroy (CS GROUP)" <chleroy@kernel.org>,
Darren Hart <dvhart@infradead.org>,
Davidlohr Bueso <dave@stgolabs.net>,
Heiko Carstens <hca@linux.ibm.com>, Jan Kara <jack@suse.cz>,
Julia Lawall <julia.lawall@inria.fr>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-arm-kernel@lists.infradead.org,
linux-fsdevel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org,
Madhavan Srinivasan <maddy@linux.ibm.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Nicholas Piggin <npiggin@gmail.com>,
Nicolas Palix <nicolas.palix@imag.fr>,
Palmer Dabbelt <palmer@dabbelt.com>,
Paul Walmsley <pjw@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Russell King <linux@armlinux.org.uk>,
Sven Schnelle <svens@linux.ibm.com>
Cc: oe-kbuild-all@lists.linux.dev, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 4/5] uaccess: Disable -Wshadow in __scoped_user_access()
Date: Thu, 5 Mar 2026 16:10:36 +0800 [thread overview]
Message-ID: <202603051642.i46zzlJ8-lkp@intel.com> (raw)
In-Reply-To: <20260302132755.1475451-5-david.laight.linux@gmail.com>
Hi,
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
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next prev parent reply other threads:[~2026-03-05 8:11 UTC|newest]
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2026-03-02 13:27 [PATCH v2 0/5] uaccess: Updates to scoped_user_access() david.laight.linux
2026-03-02 13:27 ` [PATCH v2 1/5] uaccess: Fix scoped_user_read_access() for 'pointer to const' david.laight.linux
2026-03-02 14:59 ` Christophe Leroy (CS GROUP)
2026-03-02 17:26 ` Linus Torvalds
2026-03-02 18:55 ` David Laight
2026-03-02 13:27 ` [PATCH v2 2/5] compiler.h: Add generic support for 'autoterminating nested for() loops' david.laight.linux
2026-03-02 13:27 ` [PATCH v2 3/5] uaccess.h: Use with() and and_with() in __scoped_user_access() david.laight.linux
2026-03-02 13:27 ` [PATCH v2 4/5] uaccess: Disable -Wshadow " david.laight.linux
2026-03-02 15:00 ` Christophe Leroy (CS GROUP)
2026-03-03 9:12 ` David Laight
2026-03-02 17:17 ` Linus Torvalds
2026-03-05 8:10 ` kernel test robot [this message]
2026-03-02 13:27 ` [PATCH v2 next 5/5] signal: Use scoped_user_access() instead of __put/get_user() david.laight.linux
2026-03-02 16:07 ` Christophe Leroy (CS GROUP)
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