[v3,2/4] Replace __libc_multiple_threads with __libc_single_threaded

Message ID 20220621203225.714328-3-adhemerval.zanella@linaro.org
State Committed
Commit e070501d12b47e88c1ff8c313f887976fb578938
Headers
Series Simplify internal single-threaded usage |

Checks

Context Check Description
dj/TryBot-apply_patch success Patch applied to master at the time it was sent

Commit Message

Adhemerval Zanella Netto June 21, 2022, 8:32 p.m. UTC
  And also fixes the SINGLE_THREAD_P macro for SINGLE_THREAD_BY_GLOBAL,
since header inclusion single-thread.h is in the wrong order, the define
needs to come before including sysdeps/unix/sysdep.h.  The macro
is now moved to a per-arch single-threade.h header.

The SINGLE_THREAD_P is used on some more places.

Checked on aarch64-linux-gnu and x86_64-linux-gnu.
---
 nptl/Makefile                                 |  1 -
 nptl/allocatestack.c                          |  6 ----
 nptl/libc_multiple_threads.c                  | 28 -------------------
 nptl/pthread_cancel.c                         |  2 +-
 posix/fork.c                                  |  2 +-
 sysdeps/nptl/setxid.h                         |  2 +-
 .../unix/sysv/linux/aarch64/single-thread.h   |  2 ++
 sysdeps/unix/sysv/linux/aarch64/sysdep.h      |  2 --
 sysdeps/unix/sysv/linux/alpha/sysdep.h        |  2 --
 sysdeps/unix/sysv/linux/arc/single-thread.h   |  2 ++
 sysdeps/unix/sysv/linux/arc/sysdep.h          |  2 --
 sysdeps/unix/sysv/linux/arm/single-thread.h   |  2 ++
 sysdeps/unix/sysv/linux/arm/sysdep.h          |  2 --
 sysdeps/unix/sysv/linux/hppa/single-thread.h  |  2 ++
 sysdeps/unix/sysv/linux/hppa/sysdep.h         |  2 --
 .../sysv/linux/microblaze/single-thread.h     |  2 ++
 sysdeps/unix/sysv/linux/microblaze/sysdep.h   |  2 --
 sysdeps/unix/sysv/linux/s390/single-thread.h  |  2 ++
 sysdeps/unix/sysv/linux/s390/sysdep.h         |  3 --
 sysdeps/unix/sysv/linux/single-thread.h       | 11 ++++----
 .../unix/sysv/linux/x86_64/single-thread.h    |  2 ++
 sysdeps/unix/sysv/linux/x86_64/sysdep.h       |  2 --
 22 files changed, 22 insertions(+), 61 deletions(-)
 delete mode 100644 nptl/libc_multiple_threads.c
 create mode 100644 sysdeps/unix/sysv/linux/aarch64/single-thread.h
 create mode 100644 sysdeps/unix/sysv/linux/arc/single-thread.h
 create mode 100644 sysdeps/unix/sysv/linux/arm/single-thread.h
 create mode 100644 sysdeps/unix/sysv/linux/hppa/single-thread.h
 create mode 100644 sysdeps/unix/sysv/linux/microblaze/single-thread.h
 create mode 100644 sysdeps/unix/sysv/linux/s390/single-thread.h
 create mode 100644 sysdeps/unix/sysv/linux/x86_64/single-thread.h
  

Comments

Yann Droneaud June 22, 2022, 11:04 a.m. UTC | #1
Hi,

Le 21/06/2022 à 22:32, Adhemerval Zanella via Libc-alpha a écrit :
> And also fixes the SINGLE_THREAD_P macro for SINGLE_THREAD_BY_GLOBAL,
> since header inclusion single-thread.h is in the wrong order, the define
> needs to come before including sysdeps/unix/sysdep.h.  The macro
> is now moved to a per-arch single-threade.h header.
>
> The SINGLE_THREAD_P is used on some more places.
>
> Checked on aarch64-linux-gnu and x86_64-linux-gnu.
> ---
>   nptl/Makefile                                 |  1 -
>   nptl/allocatestack.c                          |  6 ----
>   nptl/libc_multiple_threads.c                  | 28 -------------------
>   nptl/pthread_cancel.c                         |  2 +-
>   posix/fork.c                                  |  2 +-
>   sysdeps/nptl/setxid.h                         |  2 +-
>   .../unix/sysv/linux/aarch64/single-thread.h   |  2 ++
>   sysdeps/unix/sysv/linux/aarch64/sysdep.h      |  2 --
>   sysdeps/unix/sysv/linux/alpha/sysdep.h        |  2 --
>   sysdeps/unix/sysv/linux/arc/single-thread.h   |  2 ++
>   sysdeps/unix/sysv/linux/arc/sysdep.h          |  2 --
>   sysdeps/unix/sysv/linux/arm/single-thread.h   |  2 ++
>   sysdeps/unix/sysv/linux/arm/sysdep.h          |  2 --
>   sysdeps/unix/sysv/linux/hppa/single-thread.h  |  2 ++
>   sysdeps/unix/sysv/linux/hppa/sysdep.h         |  2 --
>   .../sysv/linux/microblaze/single-thread.h     |  2 ++
>   sysdeps/unix/sysv/linux/microblaze/sysdep.h   |  2 --
>   sysdeps/unix/sysv/linux/s390/single-thread.h  |  2 ++
>   sysdeps/unix/sysv/linux/s390/sysdep.h         |  3 --
>   sysdeps/unix/sysv/linux/single-thread.h       | 11 ++++----
>   .../unix/sysv/linux/x86_64/single-thread.h    |  2 ++
>   sysdeps/unix/sysv/linux/x86_64/sysdep.h       |  2 --
>   22 files changed, 22 insertions(+), 61 deletions(-)
>   delete mode 100644 nptl/libc_multiple_threads.c
>   create mode 100644 sysdeps/unix/sysv/linux/aarch64/single-thread.h
>   create mode 100644 sysdeps/unix/sysv/linux/arc/single-thread.h
>   create mode 100644 sysdeps/unix/sysv/linux/arm/single-thread.h
>   create mode 100644 sysdeps/unix/sysv/linux/hppa/single-thread.h
>   create mode 100644 sysdeps/unix/sysv/linux/microblaze/single-thread.h
>   create mode 100644 sysdeps/unix/sysv/linux/s390/single-thread.h
>   create mode 100644 sysdeps/unix/sysv/linux/x86_64/single-thread.h
>
> diff --git a/nptl/Makefile b/nptl/Makefile
> index b585663974..3d2ce8af8a 100644
> --- a/nptl/Makefile
> +++ b/nptl/Makefile
> @@ -50,7 +50,6 @@ routines = \
>     events \
>     futex-internal \
>     libc-cleanup \
> -  libc_multiple_threads \
>     lowlevellock \
>     nptl-stack \
>     nptl_deallocate_tsd \
> diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c
> index 01a282f3f6..98f5f6dd85 100644
> --- a/nptl/allocatestack.c
> +++ b/nptl/allocatestack.c
> @@ -292,9 +292,6 @@ allocate_stack (const struct pthread_attr *attr, struct pthread **pdp,
>   
>         /* This is at least the second thread.  */
>         pd->header.multiple_threads = 1;
> -#ifndef TLS_MULTIPLE_THREADS_IN_TCB
> -      __libc_multiple_threads = 1;
> -#endif
>   
>   #ifdef NEED_DL_SYSINFO
>         SETUP_THREAD_SYSINFO (pd);
> @@ -413,9 +410,6 @@ allocate_stack (const struct pthread_attr *attr, struct pthread **pdp,
>   
>   	  /* This is at least the second thread.  */
>   	  pd->header.multiple_threads = 1;
> -#ifndef TLS_MULTIPLE_THREADS_IN_TCB
> -	  __libc_multiple_threads = 1;
> -#endif
>   
>   #ifdef NEED_DL_SYSINFO
>   	  SETUP_THREAD_SYSINFO (pd);
> diff --git a/nptl/libc_multiple_threads.c b/nptl/libc_multiple_threads.c
> deleted file mode 100644
> index 0c2dc33d0d..0000000000
> --- a/nptl/libc_multiple_threads.c
> +++ /dev/null
> @@ -1,28 +0,0 @@
> -/* Copyright (C) 2002-2022 Free Software Foundation, Inc.
> -   This file is part of the GNU C Library.
> -
> -   The GNU C Library is free software; you can redistribute it and/or
> -   modify it under the terms of the GNU Lesser General Public
> -   License as published by the Free Software Foundation; either
> -   version 2.1 of the License, or (at your option) any later version.
> -
> -   The GNU C Library is distributed in the hope that it will be useful,
> -   but WITHOUT ANY WARRANTY; without even the implied warranty of
> -   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> -   Lesser General Public License for more details.
> -
> -   You should have received a copy of the GNU Lesser General Public
> -   License along with the GNU C Library; if not, see
> -   <https://www.gnu.org/licenses/>.  */
> -
> -#include <pthreadP.h>
> -
> -#if IS_IN (libc)
> -# ifndef TLS_MULTIPLE_THREADS_IN_TCB
> -/* Variable set to a nonzero value either if more than one thread runs or ran,
> -   or if a single-threaded process is trying to cancel itself.  See
> -   nptl/descr.h for more context on the single-threaded process case.  */
> -int __libc_multiple_threads;
> -libc_hidden_data_def (__libc_multiple_threads)
> -# endif
> -#endif
> diff --git a/nptl/pthread_cancel.c b/nptl/pthread_cancel.c
> index e67b2df5cc..459317df49 100644
> --- a/nptl/pthread_cancel.c
> +++ b/nptl/pthread_cancel.c
> @@ -161,7 +161,7 @@ __pthread_cancel (pthread_t th)
>   	   points get executed.  */
>   	THREAD_SETMEM (THREAD_SELF, header.multiple_threads, 1);
>   #ifndef TLS_MULTIPLE_THREADS_IN_TCB
> -      __libc_multiple_threads = 1;
> +	__libc_single_threaded_internal = 0;
>   #endif
>       }
>     while (!atomic_compare_exchange_weak_acquire (&pd->cancelhandling, &oldval,
> diff --git a/posix/fork.c b/posix/fork.c
> index 987916a175..cee5ae83c8 100644
> --- a/posix/fork.c
> +++ b/posix/fork.c
> @@ -45,7 +45,7 @@ __libc_fork (void)
>        requirement for fork (Austin Group tracker issue #62) this is
>        best effort to make is async-signal-safe at least for single-thread
>        case.  */
> -  bool multiple_threads = __libc_single_threaded_internal == 0;
> +  bool multiple_threads = !SINGLE_THREAD_P;
>     uint64_t lastrun;
>   
>     lastrun = __run_prefork_handlers (multiple_threads);
> diff --git a/sysdeps/nptl/setxid.h b/sysdeps/nptl/setxid.h
> index b87cad7b18..3a412179ac 100644
> --- a/sysdeps/nptl/setxid.h
> +++ b/sysdeps/nptl/setxid.h
> @@ -29,7 +29,7 @@
>   #define INLINE_SETXID_SYSCALL(name, nr, args...) \
>     ({									\
>       int __result;							\
> -    if (!__libc_single_threaded_internal)				\
> +    if (!SINGLE_THREAD_P)						\
>         {									\
>   	struct xid_command __cmd;					\
>   	__cmd.syscall_no = __NR_##name;					\
> diff --git a/sysdeps/unix/sysv/linux/aarch64/single-thread.h b/sysdeps/unix/sysv/linux/aarch64/single-thread.h
> new file mode 100644
> index 0000000000..a5d3a2aaf4
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/aarch64/single-thread.h
> @@ -0,0 +1,2 @@
> +#define SINGLE_THREAD_BY_GLOBAL
> +#include_next <single-thread.h>
> diff --git a/sysdeps/unix/sysv/linux/aarch64/sysdep.h b/sysdeps/unix/sysv/linux/aarch64/sysdep.h
> index 3b230dccf1..f1853e012f 100644
> --- a/sysdeps/unix/sysv/linux/aarch64/sysdep.h
> +++ b/sysdeps/unix/sysv/linux/aarch64/sysdep.h
> @@ -164,8 +164,6 @@
>   # define HAVE_CLOCK_GETTIME64_VSYSCALL	"__kernel_clock_gettime"
>   # define HAVE_GETTIMEOFDAY_VSYSCALL	"__kernel_gettimeofday"
>   
> -# define SINGLE_THREAD_BY_GLOBAL		1
> -
>   # undef INTERNAL_SYSCALL_RAW
>   # define INTERNAL_SYSCALL_RAW(name, nr, args...)		\
>     ({ long _sys_result;						\
> diff --git a/sysdeps/unix/sysv/linux/alpha/sysdep.h b/sysdeps/unix/sysv/linux/alpha/sysdep.h
> index 3051a744b4..77ec2b5400 100644
> --- a/sysdeps/unix/sysv/linux/alpha/sysdep.h
> +++ b/sysdeps/unix/sysv/linux/alpha/sysdep.h
> @@ -32,8 +32,6 @@
>   #undef SYS_ify
>   #define SYS_ify(syscall_name)	__NR_##syscall_name
>   
> -#define SINGLE_THREAD_BY_GLOBAL 1
> -
>   #ifdef __ASSEMBLER__
>   #include <asm/pal.h>
>   #include <alpha/regdef.h>
> diff --git a/sysdeps/unix/sysv/linux/arc/single-thread.h b/sysdeps/unix/sysv/linux/arc/single-thread.h
> new file mode 100644
> index 0000000000..a5d3a2aaf4
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/arc/single-thread.h
> @@ -0,0 +1,2 @@
> +#define SINGLE_THREAD_BY_GLOBAL
> +#include_next <single-thread.h>
> diff --git a/sysdeps/unix/sysv/linux/arc/sysdep.h b/sysdeps/unix/sysv/linux/arc/sysdep.h
> index 29b0e0161c..d0c1a78381 100644
> --- a/sysdeps/unix/sysv/linux/arc/sysdep.h
> +++ b/sysdeps/unix/sysv/linux/arc/sysdep.h
> @@ -132,8 +132,6 @@ L (call_syscall_err):			ASM_LINE_SEP	\
>   
>   #else  /* !__ASSEMBLER__ */
>   
> -# define SINGLE_THREAD_BY_GLOBAL		1
> -
>   # if IS_IN (libc)
>   extern long int __syscall_error (long int);
>   hidden_proto (__syscall_error)
> diff --git a/sysdeps/unix/sysv/linux/arm/single-thread.h b/sysdeps/unix/sysv/linux/arm/single-thread.h
> new file mode 100644
> index 0000000000..a5d3a2aaf4
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/arm/single-thread.h
> @@ -0,0 +1,2 @@
> +#define SINGLE_THREAD_BY_GLOBAL
> +#include_next <single-thread.h>
> diff --git a/sysdeps/unix/sysv/linux/arm/sysdep.h b/sysdeps/unix/sysv/linux/arm/sysdep.h
> index 7bdd218063..1f270b961e 100644
> --- a/sysdeps/unix/sysv/linux/arm/sysdep.h
> +++ b/sysdeps/unix/sysv/linux/arm/sysdep.h
> @@ -408,8 +408,6 @@ __local_syscall_error:						\
>   #define INTERNAL_SYSCALL_NCS(number, nr, args...)              \
>     INTERNAL_SYSCALL_RAW (number, nr, args)
>   
> -#define SINGLE_THREAD_BY_GLOBAL	1
> -
>   #endif	/* __ASSEMBLER__ */
>   
>   #endif /* linux/arm/sysdep.h */
> diff --git a/sysdeps/unix/sysv/linux/hppa/single-thread.h b/sysdeps/unix/sysv/linux/hppa/single-thread.h
> new file mode 100644
> index 0000000000..a5d3a2aaf4
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/hppa/single-thread.h
> @@ -0,0 +1,2 @@
> +#define SINGLE_THREAD_BY_GLOBAL
> +#include_next <single-thread.h>
> diff --git a/sysdeps/unix/sysv/linux/hppa/sysdep.h b/sysdeps/unix/sysv/linux/hppa/sysdep.h
> index 42f7705852..2f339a4bd6 100644
> --- a/sysdeps/unix/sysv/linux/hppa/sysdep.h
> +++ b/sysdeps/unix/sysv/linux/hppa/sysdep.h
> @@ -474,6 +474,4 @@ L(pre_end):					ASM_LINE_SEP	\
>   #define PTR_MANGLE(var) (void) (var)
>   #define PTR_DEMANGLE(var) (void) (var)
>   
> -#define SINGLE_THREAD_BY_GLOBAL	1
> -
>   #endif /* _LINUX_HPPA_SYSDEP_H */
> diff --git a/sysdeps/unix/sysv/linux/microblaze/single-thread.h b/sysdeps/unix/sysv/linux/microblaze/single-thread.h
> new file mode 100644
> index 0000000000..a5d3a2aaf4
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/microblaze/single-thread.h
> @@ -0,0 +1,2 @@
> +#define SINGLE_THREAD_BY_GLOBAL
> +#include_next <single-thread.h>
> diff --git a/sysdeps/unix/sysv/linux/microblaze/sysdep.h b/sysdeps/unix/sysv/linux/microblaze/sysdep.h
> index dfd6312506..fda78f6467 100644
> --- a/sysdeps/unix/sysv/linux/microblaze/sysdep.h
> +++ b/sysdeps/unix/sysv/linux/microblaze/sysdep.h
> @@ -308,8 +308,6 @@ SYSCALL_ERROR_LABEL_DCL:                            \
>   # define PTR_MANGLE(var) (void) (var)
>   # define PTR_DEMANGLE(var) (void) (var)
>   
> -# define SINGLE_THREAD_BY_GLOBAL	1
> -
>   #undef HAVE_INTERNAL_BRK_ADDR_SYMBOL
>   #define HAVE_INTERNAL_BRK_ADDR_SYMBOL 1
>   
> diff --git a/sysdeps/unix/sysv/linux/s390/single-thread.h b/sysdeps/unix/sysv/linux/s390/single-thread.h
> new file mode 100644
> index 0000000000..a5d3a2aaf4
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/s390/single-thread.h
> @@ -0,0 +1,2 @@
> +#define SINGLE_THREAD_BY_GLOBAL
> +#include_next <single-thread.h>
> diff --git a/sysdeps/unix/sysv/linux/s390/sysdep.h b/sysdeps/unix/sysv/linux/s390/sysdep.h
> index 78c7e8c7e2..2d0a26779c 100644
> --- a/sysdeps/unix/sysv/linux/s390/sysdep.h
> +++ b/sysdeps/unix/sysv/linux/s390/sysdep.h
> @@ -93,9 +93,6 @@
>   #define ASMFMT_5 , "0" (gpr2), "d" (gpr3), "d" (gpr4), "d" (gpr5), "d" (gpr6)
>   #define ASMFMT_6 , "0" (gpr2), "d" (gpr3), "d" (gpr4), "d" (gpr5), "d" (gpr6), "d" (gpr7)
>   
> -#define SINGLE_THREAD_BY_GLOBAL		1
> -
> -
>   #define VDSO_NAME  "LINUX_2.6.29"
>   #define VDSO_HASH  123718585
>   
> diff --git a/sysdeps/unix/sysv/linux/single-thread.h b/sysdeps/unix/sysv/linux/single-thread.h
> index 4529a906d2..30dde4e81a 100644
> --- a/sysdeps/unix/sysv/linux/single-thread.h
> +++ b/sysdeps/unix/sysv/linux/single-thread.h
> @@ -19,6 +19,10 @@
>   #ifndef _SINGLE_THREAD_H
>   #define _SINGLE_THREAD_H
>   
> +#ifndef __ASSEMBLER__
> +# include <sys/single_threaded.h>
> +#endif
> +
>   /* The default way to check if the process is single thread is by using the
>      pthread_t 'multiple_threads' field.  However, for some architectures it is
>      faster to either use an extra field on TCB or global variables (the TCB
> @@ -27,16 +31,11 @@
>      The ABI might define SINGLE_THREAD_BY_GLOBAL to enable the single thread
>      check to use global variables instead of the pthread_t field.  */
>   
> -#ifndef __ASSEMBLER__
> -extern int __libc_multiple_threads;
> -libc_hidden_proto (__libc_multiple_threads)
> -#endif
> -
>   #if !defined SINGLE_THREAD_BY_GLOBAL || IS_IN (rtld)

SINGLE_THREAD_BY_GLOBAL doesn't seem to be defined after this patch, so can it this be updated as:

- #if !defined SINGLE_THREAD_BY_GLOBAL || IS_IN (rtld)
+ #if IS_IN(rtld)

>   # define SINGLE_THREAD_P \
>     (THREAD_GETMEM (THREAD_SELF, header.multiple_threads) == 0)
>   #else
> -# define SINGLE_THREAD_P (__libc_multiple_threads == 0)
> +# define SINGLE_THREAD_P (__libc_single_threaded_internal != 0)
>   #endif
>   
>   #define RTLD_SINGLE_THREAD_P SINGLE_THREAD_P
> diff --git a/sysdeps/unix/sysv/linux/x86_64/single-thread.h b/sysdeps/unix/sysv/linux/x86_64/single-thread.h
> new file mode 100644
> index 0000000000..a5d3a2aaf4
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/x86_64/single-thread.h
> @@ -0,0 +1,2 @@
> +#define SINGLE_THREAD_BY_GLOBAL
> +#include_next <single-thread.h>
> diff --git a/sysdeps/unix/sysv/linux/x86_64/sysdep.h b/sysdeps/unix/sysv/linux/x86_64/sysdep.h
> index e1ce3b62eb..740abefcfd 100644
> --- a/sysdeps/unix/sysv/linux/x86_64/sysdep.h
> +++ b/sysdeps/unix/sysv/linux/x86_64/sysdep.h
> @@ -379,8 +379,6 @@
>   
>   # define HAVE_CLONE3_WRAPPER			1
>   
> -# define SINGLE_THREAD_BY_GLOBAL		1
> -
>   #endif	/* __ASSEMBLER__ */
>   
>   

Regards.
  
Adhemerval Zanella Netto June 22, 2022, 12:24 p.m. UTC | #2
> On 22 Jun 2022, at 08:04, Yann Droneaud <ydroneaud@opteya.com> wrote:
> 
>> diff --git a/sysdeps/unix/sysv/linux/single-thread.h b/sysdeps/unix/sysv/linux/single-thread.h
>> index 4529a906d2..30dde4e81a 100644
>> --- a/sysdeps/unix/sysv/linux/single-thread.h
>> +++ b/sysdeps/unix/sysv/linux/single-thread.h
>> @@ -19,6 +19,10 @@
>> #ifndef _SINGLE_THREAD_H
>> #define _SINGLE_THREAD_H
>> +#ifndef __ASSEMBLER__
>> +# include <sys/single_threaded.h>
>> +#endif
>> +
>> /* The default way to check if the process is single thread is by using the
>> pthread_t 'multiple_threads' field. However, for some architectures it is
>> faster to either use an extra field on TCB or global variables (the TCB
>> @@ -27,16 +31,11 @@
>> The ABI might define SINGLE_THREAD_BY_GLOBAL to enable the single thread
>> check to use global variables instead of the pthread_t field. */
>> -#ifndef __ASSEMBLER__
>> -extern int __libc_multiple_threads;
>> -libc_hidden_proto (__libc_multiple_threads)
>> -#endif
>> -
>> #if !defined SINGLE_THREAD_BY_GLOBAL || IS_IN (rtld)
> 
> SINGLE_THREAD_BY_GLOBAL doesn't seem to be defined after this patch, so can it this be updated as:

It is moved from sysdep.h to each arch-specific single-thread.h header,
so it is really used for this patch.

The third patch refactor the SINGLE_THREAD_P macro to remove the
SINGLE_THREAD_BY_GLOBAL and the forth patch finally remove all its
definition.
  
Yann Droneaud June 22, 2022, 1:53 p.m. UTC | #3
Hi,

Le 22/06/2022 à 14:24, Adhemerval Zanella via Libc-alpha a écrit :
>> On 22 Jun 2022, at 08:04, Yann Droneaud <ydroneaud@opteya.com> wrote:
>>
>>> diff --git a/sysdeps/unix/sysv/linux/single-thread.h b/sysdeps/unix/sysv/linux/single-thread.h
>>> index 4529a906d2..30dde4e81a 100644
>>> --- a/sysdeps/unix/sysv/linux/single-thread.h
>>> +++ b/sysdeps/unix/sysv/linux/single-thread.h
>>> @@ -19,6 +19,10 @@
>>> #ifndef _SINGLE_THREAD_H
>>> #define _SINGLE_THREAD_H
>>> +#ifndef __ASSEMBLER__
>>> +# include <sys/single_threaded.h>
>>> +#endif
>>> +
>>> /* The default way to check if the process is single thread is by using the
>>> pthread_t 'multiple_threads' field. However, for some architectures it is
>>> faster to either use an extra field on TCB or global variables (the TCB
>>> @@ -27,16 +31,11 @@
>>> The ABI might define SINGLE_THREAD_BY_GLOBAL to enable the single thread
>>> check to use global variables instead of the pthread_t field. */
>>> -#ifndef __ASSEMBLER__
>>> -extern int __libc_multiple_threads;
>>> -libc_hidden_proto (__libc_multiple_threads)
>>> -#endif
>>> -
>>> #if !defined SINGLE_THREAD_BY_GLOBAL || IS_IN (rtld)
>> SINGLE_THREAD_BY_GLOBAL doesn't seem to be defined after this patch, so can it this be updated as:
> It is moved from sysdep.h to each arch-specific single-thread.h header,
> so it is really used for this patch.


My bad, sorry.


Regards.
  
Wilco Dijkstra July 5, 2022, 11:34 a.m. UTC | #4
> And also fixes the SINGLE_THREAD_P macro for SINGLE_THREAD_BY_GLOBAL,
> since header inclusion single-thread.h is in the wrong order, the define
> needs to come before including sysdeps/unix/sysdep.h.  The macro
> is now moved to a per-arch single-threade.h header.
>
> The SINGLE_THREAD_P is used on some more places.
> 
> Checked on aarch64-linux-gnu and x86_64-linux-gnu.

LGTM

Cheers,
Wilco

---
 nptl/Makefile                                 |  1 -
 nptl/allocatestack.c                          |  6 ----
 nptl/libc_multiple_threads.c                  | 28 -------------------
 nptl/pthread_cancel.c                         |  2 +-
 posix/fork.c                                  |  2 +-
 sysdeps/nptl/setxid.h                         |  2 +-
 .../unix/sysv/linux/aarch64/single-thread.h   |  2 ++
 sysdeps/unix/sysv/linux/aarch64/sysdep.h      |  2 --
 sysdeps/unix/sysv/linux/alpha/sysdep.h        |  2 --
 sysdeps/unix/sysv/linux/arc/single-thread.h   |  2 ++
 sysdeps/unix/sysv/linux/arc/sysdep.h          |  2 --
 sysdeps/unix/sysv/linux/arm/single-thread.h   |  2 ++
 sysdeps/unix/sysv/linux/arm/sysdep.h          |  2 --
 sysdeps/unix/sysv/linux/hppa/single-thread.h  |  2 ++
 sysdeps/unix/sysv/linux/hppa/sysdep.h         |  2 --
 .../sysv/linux/microblaze/single-thread.h     |  2 ++
 sysdeps/unix/sysv/linux/microblaze/sysdep.h   |  2 --
 sysdeps/unix/sysv/linux/s390/single-thread.h  |  2 ++
 sysdeps/unix/sysv/linux/s390/sysdep.h         |  3 --
 sysdeps/unix/sysv/linux/single-thread.h       | 11 ++++----
 .../unix/sysv/linux/x86_64/single-thread.h    |  2 ++
 sysdeps/unix/sysv/linux/x86_64/sysdep.h       |  2 --
 22 files changed, 22 insertions(+), 61 deletions(-)
 delete mode 100644 nptl/libc_multiple_threads.c
 create mode 100644 sysdeps/unix/sysv/linux/aarch64/single-thread.h
 create mode 100644 sysdeps/unix/sysv/linux/arc/single-thread.h
 create mode 100644 sysdeps/unix/sysv/linux/arm/single-thread.h
 create mode 100644 sysdeps/unix/sysv/linux/hppa/single-thread.h
 create mode 100644 sysdeps/unix/sysv/linux/microblaze/single-thread.h
 create mode 100644 sysdeps/unix/sysv/linux/s390/single-thread.h
 create mode 100644 sysdeps/unix/sysv/linux/x86_64/single-thread.h

diff --git a/nptl/Makefile b/nptl/Makefile
index b585663974..3d2ce8af8a 100644
--- a/nptl/Makefile
+++ b/nptl/Makefile
@@ -50,7 +50,6 @@ routines = \
   events \
   futex-internal \
   libc-cleanup \
-  libc_multiple_threads \
   lowlevellock \
   nptl-stack \
   nptl_deallocate_tsd \
diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c
index 01a282f3f6..98f5f6dd85 100644
--- a/nptl/allocatestack.c
+++ b/nptl/allocatestack.c
@@ -292,9 +292,6 @@ allocate_stack (const struct pthread_attr *attr, struct pthread **pdp,
 
       /* This is at least the second thread.  */
       pd->header.multiple_threads = 1;
-#ifndef TLS_MULTIPLE_THREADS_IN_TCB
-      __libc_multiple_threads = 1;
-#endif
 
 #ifdef NEED_DL_SYSINFO
       SETUP_THREAD_SYSINFO (pd);
@@ -413,9 +410,6 @@ allocate_stack (const struct pthread_attr *attr, struct pthread **pdp,
 
           /* This is at least the second thread.  */
           pd->header.multiple_threads = 1;
-#ifndef TLS_MULTIPLE_THREADS_IN_TCB
-         __libc_multiple_threads = 1;
-#endif
 
 #ifdef NEED_DL_SYSINFO
           SETUP_THREAD_SYSINFO (pd);
diff --git a/nptl/libc_multiple_threads.c b/nptl/libc_multiple_threads.c
deleted file mode 100644
index 0c2dc33d0d..0000000000
--- a/nptl/libc_multiple_threads.c
+++ /dev/null
@@ -1,28 +0,0 @@
-/* Copyright (C) 2002-2022 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#include <pthreadP.h>
-
-#if IS_IN (libc)
-# ifndef TLS_MULTIPLE_THREADS_IN_TCB
-/* Variable set to a nonzero value either if more than one thread runs or ran,
-   or if a single-threaded process is trying to cancel itself.  See
-   nptl/descr.h for more context on the single-threaded process case.  */
-int __libc_multiple_threads;
-libc_hidden_data_def (__libc_multiple_threads)
-# endif
-#endif
diff --git a/nptl/pthread_cancel.c b/nptl/pthread_cancel.c
index e67b2df5cc..459317df49 100644
--- a/nptl/pthread_cancel.c
+++ b/nptl/pthread_cancel.c
@@ -161,7 +161,7 @@ __pthread_cancel (pthread_t th)
            points get executed.  */
         THREAD_SETMEM (THREAD_SELF, header.multiple_threads, 1);
 #ifndef TLS_MULTIPLE_THREADS_IN_TCB
-      __libc_multiple_threads = 1;
+       __libc_single_threaded_internal = 0;
 #endif
     }
   while (!atomic_compare_exchange_weak_acquire (&pd->cancelhandling, &oldval,
diff --git a/posix/fork.c b/posix/fork.c
index 987916a175..cee5ae83c8 100644
--- a/posix/fork.c
+++ b/posix/fork.c
@@ -45,7 +45,7 @@ __libc_fork (void)
      requirement for fork (Austin Group tracker issue #62) this is
      best effort to make is async-signal-safe at least for single-thread
      case.  */
-  bool multiple_threads = __libc_single_threaded_internal == 0;
+  bool multiple_threads = !SINGLE_THREAD_P;
   uint64_t lastrun;
 
   lastrun = __run_prefork_handlers (multiple_threads);
diff --git a/sysdeps/nptl/setxid.h b/sysdeps/nptl/setxid.h
index b87cad7b18..3a412179ac 100644
--- a/sysdeps/nptl/setxid.h
+++ b/sysdeps/nptl/setxid.h
@@ -29,7 +29,7 @@
 #define INLINE_SETXID_SYSCALL(name, nr, args...) \
   ({                                                                   \
     int __result;                                                      \
-    if (!__libc_single_threaded_internal)                              \
+    if (!SINGLE_THREAD_P)                                              \
       {                                                                        \
         struct xid_command __cmd;                                       \
         __cmd.syscall_no = __NR_##name;                                 \
diff --git a/sysdeps/unix/sysv/linux/aarch64/single-thread.h b/sysdeps/unix/sysv/linux/aarch64/single-thread.h
new file mode 100644
index 0000000000..a5d3a2aaf4
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/aarch64/single-thread.h
@@ -0,0 +1,2 @@
+#define SINGLE_THREAD_BY_GLOBAL
+#include_next <single-thread.h>
diff --git a/sysdeps/unix/sysv/linux/aarch64/sysdep.h b/sysdeps/unix/sysv/linux/aarch64/sysdep.h
index 3b230dccf1..f1853e012f 100644
--- a/sysdeps/unix/sysv/linux/aarch64/sysdep.h
+++ b/sysdeps/unix/sysv/linux/aarch64/sysdep.h
@@ -164,8 +164,6 @@
 # define HAVE_CLOCK_GETTIME64_VSYSCALL  "__kernel_clock_gettime"
 # define HAVE_GETTIMEOFDAY_VSYSCALL     "__kernel_gettimeofday"
 
-# define SINGLE_THREAD_BY_GLOBAL               1
-
 # undef INTERNAL_SYSCALL_RAW
 # define INTERNAL_SYSCALL_RAW(name, nr, args...)                \
   ({ long _sys_result;                                         \
diff --git a/sysdeps/unix/sysv/linux/alpha/sysdep.h b/sysdeps/unix/sysv/linux/alpha/sysdep.h
index 3051a744b4..77ec2b5400 100644
--- a/sysdeps/unix/sysv/linux/alpha/sysdep.h
+++ b/sysdeps/unix/sysv/linux/alpha/sysdep.h
@@ -32,8 +32,6 @@
 #undef SYS_ify
 #define SYS_ify(syscall_name)   __NR_##syscall_name
 
-#define SINGLE_THREAD_BY_GLOBAL 1
-
 #ifdef __ASSEMBLER__
 #include <asm/pal.h>
 #include <alpha/regdef.h>
diff --git a/sysdeps/unix/sysv/linux/arc/single-thread.h b/sysdeps/unix/sysv/linux/arc/single-thread.h
new file mode 100644
index 0000000000..a5d3a2aaf4
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/arc/single-thread.h
@@ -0,0 +1,2 @@
+#define SINGLE_THREAD_BY_GLOBAL
+#include_next <single-thread.h>
diff --git a/sysdeps/unix/sysv/linux/arc/sysdep.h b/sysdeps/unix/sysv/linux/arc/sysdep.h
index 29b0e0161c..d0c1a78381 100644
--- a/sysdeps/unix/sysv/linux/arc/sysdep.h
+++ b/sysdeps/unix/sysv/linux/arc/sysdep.h
@@ -132,8 +132,6 @@ L (call_syscall_err):                       ASM_LINE_SEP    \
 
 #else  /* !__ASSEMBLER__ */
 
-# define SINGLE_THREAD_BY_GLOBAL               1
-
 # if IS_IN (libc)
 extern long int __syscall_error (long int);
 hidden_proto (__syscall_error)
diff --git a/sysdeps/unix/sysv/linux/arm/single-thread.h b/sysdeps/unix/sysv/linux/arm/single-thread.h
new file mode 100644
index 0000000000..a5d3a2aaf4
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/arm/single-thread.h
@@ -0,0 +1,2 @@
+#define SINGLE_THREAD_BY_GLOBAL
+#include_next <single-thread.h>
diff --git a/sysdeps/unix/sysv/linux/arm/sysdep.h b/sysdeps/unix/sysv/linux/arm/sysdep.h
index 7bdd218063..1f270b961e 100644
--- a/sysdeps/unix/sysv/linux/arm/sysdep.h
+++ b/sysdeps/unix/sysv/linux/arm/sysdep.h
@@ -408,8 +408,6 @@ __local_syscall_error:                                              \
 #define INTERNAL_SYSCALL_NCS(number, nr, args...)              \
   INTERNAL_SYSCALL_RAW (number, nr, args)
 
-#define SINGLE_THREAD_BY_GLOBAL        1
-
 #endif  /* __ASSEMBLER__ */
 
 #endif /* linux/arm/sysdep.h */
diff --git a/sysdeps/unix/sysv/linux/hppa/single-thread.h b/sysdeps/unix/sysv/linux/hppa/single-thread.h
new file mode 100644
index 0000000000..a5d3a2aaf4
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/hppa/single-thread.h
@@ -0,0 +1,2 @@
+#define SINGLE_THREAD_BY_GLOBAL
+#include_next <single-thread.h>
diff --git a/sysdeps/unix/sysv/linux/hppa/sysdep.h b/sysdeps/unix/sysv/linux/hppa/sysdep.h
index 42f7705852..2f339a4bd6 100644
--- a/sysdeps/unix/sysv/linux/hppa/sysdep.h
+++ b/sysdeps/unix/sysv/linux/hppa/sysdep.h
@@ -474,6 +474,4 @@ L(pre_end):                                 ASM_LINE_SEP    \
 #define PTR_MANGLE(var) (void) (var)
 #define PTR_DEMANGLE(var) (void) (var)
 
-#define SINGLE_THREAD_BY_GLOBAL        1
-
 #endif /* _LINUX_HPPA_SYSDEP_H */
diff --git a/sysdeps/unix/sysv/linux/microblaze/single-thread.h b/sysdeps/unix/sysv/linux/microblaze/single-thread.h
new file mode 100644
index 0000000000..a5d3a2aaf4
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/microblaze/single-thread.h
@@ -0,0 +1,2 @@
+#define SINGLE_THREAD_BY_GLOBAL
+#include_next <single-thread.h>
diff --git a/sysdeps/unix/sysv/linux/microblaze/sysdep.h b/sysdeps/unix/sysv/linux/microblaze/sysdep.h
index dfd6312506..fda78f6467 100644
--- a/sysdeps/unix/sysv/linux/microblaze/sysdep.h
+++ b/sysdeps/unix/sysv/linux/microblaze/sysdep.h
@@ -308,8 +308,6 @@ SYSCALL_ERROR_LABEL_DCL:                            \
 # define PTR_MANGLE(var) (void) (var)
 # define PTR_DEMANGLE(var) (void) (var)
 
-# define SINGLE_THREAD_BY_GLOBAL       1
-
 #undef HAVE_INTERNAL_BRK_ADDR_SYMBOL
 #define HAVE_INTERNAL_BRK_ADDR_SYMBOL 1
 
diff --git a/sysdeps/unix/sysv/linux/s390/single-thread.h b/sysdeps/unix/sysv/linux/s390/single-thread.h
new file mode 100644
index 0000000000..a5d3a2aaf4
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/s390/single-thread.h
@@ -0,0 +1,2 @@
+#define SINGLE_THREAD_BY_GLOBAL
+#include_next <single-thread.h>
diff --git a/sysdeps/unix/sysv/linux/s390/sysdep.h b/sysdeps/unix/sysv/linux/s390/sysdep.h
index 78c7e8c7e2..2d0a26779c 100644
--- a/sysdeps/unix/sysv/linux/s390/sysdep.h
+++ b/sysdeps/unix/sysv/linux/s390/sysdep.h
@@ -93,9 +93,6 @@
 #define ASMFMT_5 , "0" (gpr2), "d" (gpr3), "d" (gpr4), "d" (gpr5), "d" (gpr6)
 #define ASMFMT_6 , "0" (gpr2), "d" (gpr3), "d" (gpr4), "d" (gpr5), "d" (gpr6), "d" (gpr7)
 
-#define SINGLE_THREAD_BY_GLOBAL                1
-
-
 #define VDSO_NAME  "LINUX_2.6.29"
 #define VDSO_HASH  123718585
 
diff --git a/sysdeps/unix/sysv/linux/single-thread.h b/sysdeps/unix/sysv/linux/single-thread.h
index 4529a906d2..30dde4e81a 100644
--- a/sysdeps/unix/sysv/linux/single-thread.h
+++ b/sysdeps/unix/sysv/linux/single-thread.h
@@ -19,6 +19,10 @@
 #ifndef _SINGLE_THREAD_H
 #define _SINGLE_THREAD_H
 
+#ifndef __ASSEMBLER__
+# include <sys/single_threaded.h>
+#endif
+
 /* The default way to check if the process is single thread is by using the
    pthread_t 'multiple_threads' field.  However, for some architectures it is
    faster to either use an extra field on TCB or global variables (the TCB
@@ -27,16 +31,11 @@
    The ABI might define SINGLE_THREAD_BY_GLOBAL to enable the single thread
    check to use global variables instead of the pthread_t field.  */
 
-#ifndef __ASSEMBLER__
-extern int __libc_multiple_threads;
-libc_hidden_proto (__libc_multiple_threads)
-#endif
-
 #if !defined SINGLE_THREAD_BY_GLOBAL || IS_IN (rtld)
 # define SINGLE_THREAD_P \
   (THREAD_GETMEM (THREAD_SELF, header.multiple_threads) == 0)
 #else
-# define SINGLE_THREAD_P (__libc_multiple_threads == 0)
+# define SINGLE_THREAD_P (__libc_single_threaded_internal != 0)
 #endif
 
 #define RTLD_SINGLE_THREAD_P SINGLE_THREAD_P
diff --git a/sysdeps/unix/sysv/linux/x86_64/single-thread.h b/sysdeps/unix/sysv/linux/x86_64/single-thread.h
new file mode 100644
index 0000000000..a5d3a2aaf4
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86_64/single-thread.h
@@ -0,0 +1,2 @@
+#define SINGLE_THREAD_BY_GLOBAL
+#include_next <single-thread.h>
diff --git a/sysdeps/unix/sysv/linux/x86_64/sysdep.h b/sysdeps/unix/sysv/linux/x86_64/sysdep.h
index e1ce3b62eb..740abefcfd 100644
--- a/sysdeps/unix/sysv/linux/x86_64/sysdep.h
+++ b/sysdeps/unix/sysv/linux/x86_64/sysdep.h
@@ -379,8 +379,6 @@
 
 # define HAVE_CLONE3_WRAPPER                    1
 
-# define SINGLE_THREAD_BY_GLOBAL               1
-
 #endif  /* __ASSEMBLER__ */
  

Patch

diff --git a/nptl/Makefile b/nptl/Makefile
index b585663974..3d2ce8af8a 100644
--- a/nptl/Makefile
+++ b/nptl/Makefile
@@ -50,7 +50,6 @@  routines = \
   events \
   futex-internal \
   libc-cleanup \
-  libc_multiple_threads \
   lowlevellock \
   nptl-stack \
   nptl_deallocate_tsd \
diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c
index 01a282f3f6..98f5f6dd85 100644
--- a/nptl/allocatestack.c
+++ b/nptl/allocatestack.c
@@ -292,9 +292,6 @@  allocate_stack (const struct pthread_attr *attr, struct pthread **pdp,
 
       /* This is at least the second thread.  */
       pd->header.multiple_threads = 1;
-#ifndef TLS_MULTIPLE_THREADS_IN_TCB
-      __libc_multiple_threads = 1;
-#endif
 
 #ifdef NEED_DL_SYSINFO
       SETUP_THREAD_SYSINFO (pd);
@@ -413,9 +410,6 @@  allocate_stack (const struct pthread_attr *attr, struct pthread **pdp,
 
 	  /* This is at least the second thread.  */
 	  pd->header.multiple_threads = 1;
-#ifndef TLS_MULTIPLE_THREADS_IN_TCB
-	  __libc_multiple_threads = 1;
-#endif
 
 #ifdef NEED_DL_SYSINFO
 	  SETUP_THREAD_SYSINFO (pd);
diff --git a/nptl/libc_multiple_threads.c b/nptl/libc_multiple_threads.c
deleted file mode 100644
index 0c2dc33d0d..0000000000
--- a/nptl/libc_multiple_threads.c
+++ /dev/null
@@ -1,28 +0,0 @@ 
-/* Copyright (C) 2002-2022 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#include <pthreadP.h>
-
-#if IS_IN (libc)
-# ifndef TLS_MULTIPLE_THREADS_IN_TCB
-/* Variable set to a nonzero value either if more than one thread runs or ran,
-   or if a single-threaded process is trying to cancel itself.  See
-   nptl/descr.h for more context on the single-threaded process case.  */
-int __libc_multiple_threads;
-libc_hidden_data_def (__libc_multiple_threads)
-# endif
-#endif
diff --git a/nptl/pthread_cancel.c b/nptl/pthread_cancel.c
index e67b2df5cc..459317df49 100644
--- a/nptl/pthread_cancel.c
+++ b/nptl/pthread_cancel.c
@@ -161,7 +161,7 @@  __pthread_cancel (pthread_t th)
 	   points get executed.  */
 	THREAD_SETMEM (THREAD_SELF, header.multiple_threads, 1);
 #ifndef TLS_MULTIPLE_THREADS_IN_TCB
-      __libc_multiple_threads = 1;
+	__libc_single_threaded_internal = 0;
 #endif
     }
   while (!atomic_compare_exchange_weak_acquire (&pd->cancelhandling, &oldval,
diff --git a/posix/fork.c b/posix/fork.c
index 987916a175..cee5ae83c8 100644
--- a/posix/fork.c
+++ b/posix/fork.c
@@ -45,7 +45,7 @@  __libc_fork (void)
      requirement for fork (Austin Group tracker issue #62) this is
      best effort to make is async-signal-safe at least for single-thread
      case.  */
-  bool multiple_threads = __libc_single_threaded_internal == 0;
+  bool multiple_threads = !SINGLE_THREAD_P;
   uint64_t lastrun;
 
   lastrun = __run_prefork_handlers (multiple_threads);
diff --git a/sysdeps/nptl/setxid.h b/sysdeps/nptl/setxid.h
index b87cad7b18..3a412179ac 100644
--- a/sysdeps/nptl/setxid.h
+++ b/sysdeps/nptl/setxid.h
@@ -29,7 +29,7 @@ 
 #define INLINE_SETXID_SYSCALL(name, nr, args...) \
   ({									\
     int __result;							\
-    if (!__libc_single_threaded_internal)				\
+    if (!SINGLE_THREAD_P)						\
       {									\
 	struct xid_command __cmd;					\
 	__cmd.syscall_no = __NR_##name;					\
diff --git a/sysdeps/unix/sysv/linux/aarch64/single-thread.h b/sysdeps/unix/sysv/linux/aarch64/single-thread.h
new file mode 100644
index 0000000000..a5d3a2aaf4
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/aarch64/single-thread.h
@@ -0,0 +1,2 @@ 
+#define SINGLE_THREAD_BY_GLOBAL
+#include_next <single-thread.h>
diff --git a/sysdeps/unix/sysv/linux/aarch64/sysdep.h b/sysdeps/unix/sysv/linux/aarch64/sysdep.h
index 3b230dccf1..f1853e012f 100644
--- a/sysdeps/unix/sysv/linux/aarch64/sysdep.h
+++ b/sysdeps/unix/sysv/linux/aarch64/sysdep.h
@@ -164,8 +164,6 @@ 
 # define HAVE_CLOCK_GETTIME64_VSYSCALL	"__kernel_clock_gettime"
 # define HAVE_GETTIMEOFDAY_VSYSCALL	"__kernel_gettimeofday"
 
-# define SINGLE_THREAD_BY_GLOBAL		1
-
 # undef INTERNAL_SYSCALL_RAW
 # define INTERNAL_SYSCALL_RAW(name, nr, args...)		\
   ({ long _sys_result;						\
diff --git a/sysdeps/unix/sysv/linux/alpha/sysdep.h b/sysdeps/unix/sysv/linux/alpha/sysdep.h
index 3051a744b4..77ec2b5400 100644
--- a/sysdeps/unix/sysv/linux/alpha/sysdep.h
+++ b/sysdeps/unix/sysv/linux/alpha/sysdep.h
@@ -32,8 +32,6 @@ 
 #undef SYS_ify
 #define SYS_ify(syscall_name)	__NR_##syscall_name
 
-#define SINGLE_THREAD_BY_GLOBAL 1
-
 #ifdef __ASSEMBLER__
 #include <asm/pal.h>
 #include <alpha/regdef.h>
diff --git a/sysdeps/unix/sysv/linux/arc/single-thread.h b/sysdeps/unix/sysv/linux/arc/single-thread.h
new file mode 100644
index 0000000000..a5d3a2aaf4
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/arc/single-thread.h
@@ -0,0 +1,2 @@ 
+#define SINGLE_THREAD_BY_GLOBAL
+#include_next <single-thread.h>
diff --git a/sysdeps/unix/sysv/linux/arc/sysdep.h b/sysdeps/unix/sysv/linux/arc/sysdep.h
index 29b0e0161c..d0c1a78381 100644
--- a/sysdeps/unix/sysv/linux/arc/sysdep.h
+++ b/sysdeps/unix/sysv/linux/arc/sysdep.h
@@ -132,8 +132,6 @@  L (call_syscall_err):			ASM_LINE_SEP	\
 
 #else  /* !__ASSEMBLER__ */
 
-# define SINGLE_THREAD_BY_GLOBAL		1
-
 # if IS_IN (libc)
 extern long int __syscall_error (long int);
 hidden_proto (__syscall_error)
diff --git a/sysdeps/unix/sysv/linux/arm/single-thread.h b/sysdeps/unix/sysv/linux/arm/single-thread.h
new file mode 100644
index 0000000000..a5d3a2aaf4
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/arm/single-thread.h
@@ -0,0 +1,2 @@ 
+#define SINGLE_THREAD_BY_GLOBAL
+#include_next <single-thread.h>
diff --git a/sysdeps/unix/sysv/linux/arm/sysdep.h b/sysdeps/unix/sysv/linux/arm/sysdep.h
index 7bdd218063..1f270b961e 100644
--- a/sysdeps/unix/sysv/linux/arm/sysdep.h
+++ b/sysdeps/unix/sysv/linux/arm/sysdep.h
@@ -408,8 +408,6 @@  __local_syscall_error:						\
 #define INTERNAL_SYSCALL_NCS(number, nr, args...)              \
   INTERNAL_SYSCALL_RAW (number, nr, args)
 
-#define SINGLE_THREAD_BY_GLOBAL	1
-
 #endif	/* __ASSEMBLER__ */
 
 #endif /* linux/arm/sysdep.h */
diff --git a/sysdeps/unix/sysv/linux/hppa/single-thread.h b/sysdeps/unix/sysv/linux/hppa/single-thread.h
new file mode 100644
index 0000000000..a5d3a2aaf4
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/hppa/single-thread.h
@@ -0,0 +1,2 @@ 
+#define SINGLE_THREAD_BY_GLOBAL
+#include_next <single-thread.h>
diff --git a/sysdeps/unix/sysv/linux/hppa/sysdep.h b/sysdeps/unix/sysv/linux/hppa/sysdep.h
index 42f7705852..2f339a4bd6 100644
--- a/sysdeps/unix/sysv/linux/hppa/sysdep.h
+++ b/sysdeps/unix/sysv/linux/hppa/sysdep.h
@@ -474,6 +474,4 @@  L(pre_end):					ASM_LINE_SEP	\
 #define PTR_MANGLE(var) (void) (var)
 #define PTR_DEMANGLE(var) (void) (var)
 
-#define SINGLE_THREAD_BY_GLOBAL	1
-
 #endif /* _LINUX_HPPA_SYSDEP_H */
diff --git a/sysdeps/unix/sysv/linux/microblaze/single-thread.h b/sysdeps/unix/sysv/linux/microblaze/single-thread.h
new file mode 100644
index 0000000000..a5d3a2aaf4
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/microblaze/single-thread.h
@@ -0,0 +1,2 @@ 
+#define SINGLE_THREAD_BY_GLOBAL
+#include_next <single-thread.h>
diff --git a/sysdeps/unix/sysv/linux/microblaze/sysdep.h b/sysdeps/unix/sysv/linux/microblaze/sysdep.h
index dfd6312506..fda78f6467 100644
--- a/sysdeps/unix/sysv/linux/microblaze/sysdep.h
+++ b/sysdeps/unix/sysv/linux/microblaze/sysdep.h
@@ -308,8 +308,6 @@  SYSCALL_ERROR_LABEL_DCL:                            \
 # define PTR_MANGLE(var) (void) (var)
 # define PTR_DEMANGLE(var) (void) (var)
 
-# define SINGLE_THREAD_BY_GLOBAL	1
-
 #undef HAVE_INTERNAL_BRK_ADDR_SYMBOL
 #define HAVE_INTERNAL_BRK_ADDR_SYMBOL 1
 
diff --git a/sysdeps/unix/sysv/linux/s390/single-thread.h b/sysdeps/unix/sysv/linux/s390/single-thread.h
new file mode 100644
index 0000000000..a5d3a2aaf4
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/s390/single-thread.h
@@ -0,0 +1,2 @@ 
+#define SINGLE_THREAD_BY_GLOBAL
+#include_next <single-thread.h>
diff --git a/sysdeps/unix/sysv/linux/s390/sysdep.h b/sysdeps/unix/sysv/linux/s390/sysdep.h
index 78c7e8c7e2..2d0a26779c 100644
--- a/sysdeps/unix/sysv/linux/s390/sysdep.h
+++ b/sysdeps/unix/sysv/linux/s390/sysdep.h
@@ -93,9 +93,6 @@ 
 #define ASMFMT_5 , "0" (gpr2), "d" (gpr3), "d" (gpr4), "d" (gpr5), "d" (gpr6)
 #define ASMFMT_6 , "0" (gpr2), "d" (gpr3), "d" (gpr4), "d" (gpr5), "d" (gpr6), "d" (gpr7)
 
-#define SINGLE_THREAD_BY_GLOBAL		1
-
-
 #define VDSO_NAME  "LINUX_2.6.29"
 #define VDSO_HASH  123718585
 
diff --git a/sysdeps/unix/sysv/linux/single-thread.h b/sysdeps/unix/sysv/linux/single-thread.h
index 4529a906d2..30dde4e81a 100644
--- a/sysdeps/unix/sysv/linux/single-thread.h
+++ b/sysdeps/unix/sysv/linux/single-thread.h
@@ -19,6 +19,10 @@ 
 #ifndef _SINGLE_THREAD_H
 #define _SINGLE_THREAD_H
 
+#ifndef __ASSEMBLER__
+# include <sys/single_threaded.h>
+#endif
+
 /* The default way to check if the process is single thread is by using the
    pthread_t 'multiple_threads' field.  However, for some architectures it is
    faster to either use an extra field on TCB or global variables (the TCB
@@ -27,16 +31,11 @@ 
    The ABI might define SINGLE_THREAD_BY_GLOBAL to enable the single thread
    check to use global variables instead of the pthread_t field.  */
 
-#ifndef __ASSEMBLER__
-extern int __libc_multiple_threads;
-libc_hidden_proto (__libc_multiple_threads)
-#endif
-
 #if !defined SINGLE_THREAD_BY_GLOBAL || IS_IN (rtld)
 # define SINGLE_THREAD_P \
   (THREAD_GETMEM (THREAD_SELF, header.multiple_threads) == 0)
 #else
-# define SINGLE_THREAD_P (__libc_multiple_threads == 0)
+# define SINGLE_THREAD_P (__libc_single_threaded_internal != 0)
 #endif
 
 #define RTLD_SINGLE_THREAD_P SINGLE_THREAD_P
diff --git a/sysdeps/unix/sysv/linux/x86_64/single-thread.h b/sysdeps/unix/sysv/linux/x86_64/single-thread.h
new file mode 100644
index 0000000000..a5d3a2aaf4
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86_64/single-thread.h
@@ -0,0 +1,2 @@ 
+#define SINGLE_THREAD_BY_GLOBAL
+#include_next <single-thread.h>
diff --git a/sysdeps/unix/sysv/linux/x86_64/sysdep.h b/sysdeps/unix/sysv/linux/x86_64/sysdep.h
index e1ce3b62eb..740abefcfd 100644
--- a/sysdeps/unix/sysv/linux/x86_64/sysdep.h
+++ b/sysdeps/unix/sysv/linux/x86_64/sysdep.h
@@ -379,8 +379,6 @@ 
 
 # define HAVE_CLONE3_WRAPPER			1
 
-# define SINGLE_THREAD_BY_GLOBAL		1
-
 #endif	/* __ASSEMBLER__ */