Re: [PATCH 1/4] Add single-thread.h header

[Adhemerval Zanella <adhemerval dot zanella at linaro dot org>]

If no one opposes it, I will commit this shortly (the rest of patchset
is already accepted).

On 09/05/2019 15:25, Adhemerval Zanella wrote:
> Ping (x2).  This is mostly a refactor patch, no semantic changes
> are expected.
> 
> On 09/04/2019 09:11, Adhemerval Zanella wrote:
>> Ping.
>>
>> On 22/02/2019 16:27, Adhemerval Zanella wrote:
>>> This patch move the single-thread syscall optimization defintions from
>>> syscall-cancel.h to new header file single-thread.h and also move the
>>> cancellation definitions from pthreadP.h to syscall-cancel.h.
>>>
>>> The idea is just simplify the inclusion of both syscall-cancel.h and
>>> single-thread.h (without the requirement of including all pthreadP.h
>>> defintions).
>>>
>>> No semantic changes expected, checked on a build for all major ABIs.
>>>
>>> 	* nptl/pthreadP.h (CANCEL_ASYNC, CANCEL_RESET, LIBC_CANCEL_ASYNC,
>>> 	LIBC_CANCEL_RESET, __libc_enable_asynccancel,
>>> 	__libc_disable_asynccancel, __librt_enable_asynccancel,
>>> 	__libc_disable_asynccancel, __librt_enable_asynccancel,
>>> 	__librt_disable_asynccancel): Move to ...
>>> 	* sysdeps/unix/sysv/linux/sysdep-cancel.h: ... here.
>>> 	(SINGLE_THREAD_P, RTLD_SINGLE_THREAD_P): Move to ...
>>> 	* sysdeps/unix/sysv/linux/single-thread.h: ... here.
>>> 	* sysdeps/generic/single-thread.h: New file.
>>> 	* sysdeps/unix/sysdep.h: Include single-thread.h.
>>> 	* sysdeps/unix/sysv/linux/futex-internal.h: Include sysdep-cancel.h.
>>> 	* sysdeps/unix/sysv/linux/lowlevellock-futex.h: Likewise.
>>> ---
>>>  nptl/pthreadP.h                              | 37 ---------
>>>  sysdeps/generic/single-thread.h              | 24 ++++++
>>>  sysdeps/unix/sysdep.h                        |  2 +-
>>>  sysdeps/unix/sysv/linux/futex-internal.h     |  2 +-
>>>  sysdeps/unix/sysv/linux/lowlevellock-futex.h |  2 +-
>>>  sysdeps/unix/sysv/linux/single-thread.h      | 64 ++++++++++++++++
>>>  sysdeps/unix/sysv/linux/sysdep-cancel.h      | 81 ++++++++++----------
>>>  7 files changed, 133 insertions(+), 79 deletions(-)
>>>  create mode 100644 sysdeps/generic/single-thread.h
>>>  create mode 100644 sysdeps/unix/sysv/linux/single-thread.h
>>>
>>> diff --git a/nptl/pthreadP.h b/nptl/pthreadP.h
>>> index 626bd4b096..0beacd1266 100644
>>> --- a/nptl/pthreadP.h
>>> +++ b/nptl/pthreadP.h
>>> @@ -311,34 +311,6 @@ __do_cancel (void)
>>>  }
>>>  
>>>  
>>> -/* Set cancellation mode to asynchronous.  */
>>> -#define CANCEL_ASYNC() \
>>> -  __pthread_enable_asynccancel ()
>>> -/* Reset to previous cancellation mode.  */
>>> -#define CANCEL_RESET(oldtype) \
>>> -  __pthread_disable_asynccancel (oldtype)
>>> -
>>> -#if IS_IN (libc)
>>> -/* Same as CANCEL_ASYNC, but for use in libc.so.  */
>>> -# define LIBC_CANCEL_ASYNC() \
>>> -  __libc_enable_asynccancel ()
>>> -/* Same as CANCEL_RESET, but for use in libc.so.  */
>>> -# define LIBC_CANCEL_RESET(oldtype) \
>>> -  __libc_disable_asynccancel (oldtype)
>>> -#elif IS_IN (libpthread)
>>> -# define LIBC_CANCEL_ASYNC() CANCEL_ASYNC ()
>>> -# define LIBC_CANCEL_RESET(val) CANCEL_RESET (val)
>>> -#elif IS_IN (librt)
>>> -# define LIBC_CANCEL_ASYNC() \
>>> -  __librt_enable_asynccancel ()
>>> -# define LIBC_CANCEL_RESET(val) \
>>> -  __librt_disable_asynccancel (val)
>>> -#else
>>> -# define LIBC_CANCEL_ASYNC()	0 /* Just a dummy value.  */
>>> -# define LIBC_CANCEL_RESET(val)	((void)(val)) /* Nothing, but evaluate it.  */
>>> -#endif
>>> -
>>> -
>>>  /* Internal prototypes.  */
>>>  
>>>  /* Thread list handling.  */
>>> @@ -545,15 +517,6 @@ extern int __pthread_cond_wait_2_0 (pthread_cond_2_0_t *cond,
>>>  extern int __pthread_getaffinity_np (pthread_t th, size_t cpusetsize,
>>>  				     cpu_set_t *cpuset);
>>>  
>>> -/* The two functions are in libc.so and not exported.  */
>>> -extern int __libc_enable_asynccancel (void) attribute_hidden;
>>> -extern void __libc_disable_asynccancel (int oldtype) attribute_hidden;
>>> -
>>> -
>>> -/* The two functions are in librt.so and not exported.  */
>>> -extern int __librt_enable_asynccancel (void) attribute_hidden;
>>> -extern void __librt_disable_asynccancel (int oldtype) attribute_hidden;
>>> -
>>>  #if IS_IN (libpthread)
>>>  /* Special versions which use non-exported functions.  */
>>>  extern void __pthread_cleanup_push (struct _pthread_cleanup_buffer *buffer,
>>> diff --git a/sysdeps/generic/single-thread.h b/sysdeps/generic/single-thread.h
>>> new file mode 100644
>>> index 0000000000..0a1520ec49
>>> --- /dev/null
>>> +++ b/sysdeps/generic/single-thread.h
>>> @@ -0,0 +1,24 @@
>>> +/* Single thread optimization, generic version.
>>> +   Copyright (C) 2019 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
>>> +   <http://www.gnu.org/licenses/>.  */
>>> +
>>> +#ifndef _SINGLE_THREAD_H
>>> +#define _SINGLE_THREAD_H
>>> +
>>> +#define SINGLE_THREAD_P (0)
>>> +
>>> +#endif /* _SINGLE_THREAD_H  */
>>> diff --git a/sysdeps/unix/sysdep.h b/sysdeps/unix/sysdep.h
>>> index 7cb6c89825..6e503d7688 100644
>>> --- a/sysdeps/unix/sysdep.h
>>> +++ b/sysdeps/unix/sysdep.h
>>> @@ -16,7 +16,7 @@
>>>     <http://www.gnu.org/licenses/>.  */
>>>  
>>>  #include <sysdeps/generic/sysdep.h>
>>> -
>>> +#include <single-thread.h>
>>>  #include <sys/syscall.h>
>>>  #define	HAVE_SYSCALLS
>>>  
>>> diff --git a/sysdeps/unix/sysv/linux/futex-internal.h b/sysdeps/unix/sysv/linux/futex-internal.h
>>> index 55f0fab77c..501f993853 100644
>>> --- a/sysdeps/unix/sysv/linux/futex-internal.h
>>> +++ b/sysdeps/unix/sysv/linux/futex-internal.h
>>> @@ -22,7 +22,7 @@
>>>  #include <sysdeps/nptl/futex-internal.h>
>>>  #include <errno.h>
>>>  #include <lowlevellock-futex.h>
>>> -#include <nptl/pthreadP.h>
>>> +#include <sysdep-cancel.h>
>>>  
>>>  /* See sysdeps/nptl/futex-internal.h for documentation; this file only
>>>     contains Linux-specific comments.
>>> diff --git a/sysdeps/unix/sysv/linux/lowlevellock-futex.h b/sysdeps/unix/sysv/linux/lowlevellock-futex.h
>>> index 6f060b1739..030a14b8dc 100644
>>> --- a/sysdeps/unix/sysv/linux/lowlevellock-futex.h
>>> +++ b/sysdeps/unix/sysv/linux/lowlevellock-futex.h
>>> @@ -21,7 +21,7 @@
>>>  
>>>  #ifndef __ASSEMBLER__
>>>  #include <sysdep.h>
>>> -#include <tls.h>
>>> +#include <sysdep-cancel.h>
>>>  #include <kernel-features.h>
>>>  #endif
>>>  
>>> diff --git a/sysdeps/unix/sysv/linux/single-thread.h b/sysdeps/unix/sysv/linux/single-thread.h
>>> new file mode 100644
>>> index 0000000000..8248c5d8b8
>>> --- /dev/null
>>> +++ b/sysdeps/unix/sysv/linux/single-thread.h
>>> @@ -0,0 +1,64 @@
>>> +/* Single thread optimization, Linux version.
>>> +   Copyright (C) 2019 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
>>> +   <http://www.gnu.org/licenses/>.  */
>>> +
>>> +#ifndef _SINGLE_THREAD_H
>>> +#define _SINGLE_THREAD_H
>>> +
>>> +/* 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 varibles
>>> +   (the TCB field is also used on x86 for some single-thread atomic
>>> +   optimizations).
>>> +
>>> +   The ABI might define SINGLE_THREAD_BY_GLOBAL to enable the single
>>> +   thread check to use global variables instead of the pthread_t
>>> +   field.  */
>>> +
>>> +#ifdef SINGLE_THREAD_BY_GLOBAL
>>> +# if IS_IN (libc)
>>> +extern int __libc_multiple_threads;
>>> +#  define SINGLE_THREAD_P \
>>> +  __glibc_likely (__libc_multiple_threads == 0)
>>> +# elif IS_IN (libpthread)
>>> +extern int __pthread_multiple_threads;
>>> +#  define SINGLE_THREAD_P \
>>> +  __glibc_likely (__pthread_multiple_threads == 0)
>>> +# elif IS_IN (librt)
>>> +#   define SINGLE_THREAD_P					\
>>> +  __glibc_likely (THREAD_GETMEM (THREAD_SELF,			\
>>> +				 header.multiple_threads) == 0)
>>> +# else
>>> +/* For rtld, et cetera.  */
>>> +#  define SINGLE_THREAD_P (1)
>>> +# endif
>>> +#else /* SINGLE_THREAD_BY_GLOBAL  */
>>> +# if IS_IN (libc) || IS_IN (libpthread) || IS_IN (librt)
>>> +#   define SINGLE_THREAD_P					\
>>> +  __glibc_likely (THREAD_GETMEM (THREAD_SELF,			\
>>> +				 header.multiple_threads) == 0)
>>> +# else
>>> +/* For rtld, et cetera.  */
>>> +#  define SINGLE_THREAD_P (1)
>>> +# endif
>>> +#endif /* SINGLE_THREAD_BY_GLOBAL  */
>>> +
>>> +#define RTLD_SINGLE_THREAD_P \
>>> +  __glibc_likely (THREAD_GETMEM (THREAD_SELF, \
>>> +				 header.multiple_threads) == 0)
>>> +
>>> +#endif /* _SINGLE_THREAD_H  */
>>> diff --git a/sysdeps/unix/sysv/linux/sysdep-cancel.h b/sysdeps/unix/sysv/linux/sysdep-cancel.h
>>> index 896549c7f7..a831b30106 100644
>>> --- a/sysdeps/unix/sysv/linux/sysdep-cancel.h
>>> +++ b/sysdeps/unix/sysv/linux/sysdep-cancel.h
>>> @@ -17,48 +17,51 @@
>>>     License along with the GNU C Library; if not, see
>>>     <http://www.gnu.org/licenses/>.  */
>>>  
>>> +#ifndef _SYSDEP_CANCEL_H
>>> +#define _SYSDEP_CANCEL_H
>>> +
>>>  #include <sysdep.h>
>>>  #include <tls.h>
>>> -#include <nptl/pthreadP.h>
>>> +#include <errno.h>
>>> +
>>> +/* The two functions are in libc.so and not exported.  */
>>> +extern int __libc_enable_asynccancel (void) attribute_hidden;
>>> +extern void __libc_disable_asynccancel (int oldtype) attribute_hidden;
>>> +
>>> +/* The two functions are in librt.so and not exported.  */
>>> +extern int __librt_enable_asynccancel (void) attribute_hidden;
>>> +extern void __librt_disable_asynccancel (int oldtype) attribute_hidden;
>>> +
>>> +/* The two functions are in libpthread.so and not exported.  */
>>> +extern int __pthread_enable_asynccancel (void) attribute_hidden;
>>> +extern void __pthread_disable_asynccancel (int oldtype) attribute_hidden;
>>>  
>>> -/* 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 varibles
>>> -   (the TCB field is also used on x86 for some single-thread atomic
>>> -   optimizations).
>>> +/* Set cancellation mode to asynchronous.  */
>>> +#define CANCEL_ASYNC() \
>>> +  __pthread_enable_asynccancel ()
>>> +/* Reset to previous cancellation mode.  */
>>> +#define CANCEL_RESET(oldtype) \
>>> +  __pthread_disable_asynccancel (oldtype)
>>>  
>>> -   The ABI might define SINGLE_THREAD_BY_GLOBAL to enable the single
>>> -   thread check to use global variables instead of the pthread_t
>>> -   field.  */
>>> +#if IS_IN (libc)
>>> +/* Same as CANCEL_ASYNC, but for use in libc.so.  */
>>> +# define LIBC_CANCEL_ASYNC() \
>>> +  __libc_enable_asynccancel ()
>>> +/* Same as CANCEL_RESET, but for use in libc.so.  */
>>> +# define LIBC_CANCEL_RESET(oldtype) \
>>> +  __libc_disable_asynccancel (oldtype)
>>> +#elif IS_IN (libpthread)
>>> +# define LIBC_CANCEL_ASYNC() CANCEL_ASYNC ()
>>> +# define LIBC_CANCEL_RESET(val) CANCEL_RESET (val)
>>> +#elif IS_IN (librt)
>>> +# define LIBC_CANCEL_ASYNC() \
>>> +  __librt_enable_asynccancel ()
>>> +# define LIBC_CANCEL_RESET(val) \
>>> +  __librt_disable_asynccancel (val)
>>> +#else
>>> +# define LIBC_CANCEL_ASYNC()	0 /* Just a dummy value.  */
>>> +# define LIBC_CANCEL_RESET(val)	((void)(val)) /* Nothing, but evaluate it.  */
>>> +#endif
>>>  
>>> -#ifdef SINGLE_THREAD_BY_GLOBAL
>>> -# if IS_IN (libc)
>>> -extern int __libc_multiple_threads;
>>> -#  define SINGLE_THREAD_P \
>>> -  __glibc_likely (__libc_multiple_threads == 0)
>>> -# elif IS_IN (libpthread)
>>> -extern int __pthread_multiple_threads;
>>> -#  define SINGLE_THREAD_P \
>>> -  __glibc_likely (__pthread_multiple_threads == 0)
>>> -# elif IS_IN (librt)
>>> -#   define SINGLE_THREAD_P					\
>>> -  __glibc_likely (THREAD_GETMEM (THREAD_SELF,			\
>>> -				 header.multiple_threads) == 0)
>>> -# else
>>> -/* For rtld, et cetera.  */
>>> -#  define SINGLE_THREAD_P (1)
>>> -# endif
>>> -#else /* SINGLE_THREAD_BY_GLOBAL  */
>>> -# if IS_IN (libc) || IS_IN (libpthread) || IS_IN (librt)
>>> -#   define SINGLE_THREAD_P					\
>>> -  __glibc_likely (THREAD_GETMEM (THREAD_SELF,			\
>>> -				 header.multiple_threads) == 0)
>>> -# else
>>> -/* For rtld, et cetera.  */
>>> -#  define SINGLE_THREAD_P (1)
>>> -# endif
>>> -#endif /* SINGLE_THREAD_BY_GLOBAL  */
>>>  
>>> -#define RTLD_SINGLE_THREAD_P \
>>> -  __glibc_likely (THREAD_GETMEM (THREAD_SELF, \
>>> -				 header.multiple_threads) == 0)
>>> +#endif
>>>