Re: [PATCH v8 2/8] nptl: Add C11 threads mtx_* functions

[Carlos O'Donell <carlos@redhat.com>]

On 07/24/2018 08:04 AM, Adhemerval Zanella wrote:
> Updated patch from Carlos suggestion.  Changes from previous version:
> 
>   - Remove an extra mtx_destroy on nptl/Versions.
>   - Adjusted the wording on cnd_init static asserts.
>   - Add bugzilla entry and adjusted glibc version on CL.
> 
> ---
> 
> This patch adds the cnd_* definitions from C11 threads (ISO/IEC 9899:2011),
> more specifically cnd_broadcast, cnd_destroy, cnd_init, cnd_signal,
> cnd_timedwait, cnd_wait, and required types.
> 

OK.

I confirm going through the standard and I see:

cnd_t, cnd_broadcast, cnd_destroy, cnd_init, cnd_signal, cnd_timedwait,
and cnd_wait as the only condvar functions in use.

The rest of the usage requires the mutex support which has already
been reviewed.

> Mostly of the definitions are composed based on POSIX conterparts, and
> cnd_t is also based on internal pthreads fields, but with distinct internal
> layout to avoid possible issues with code interchange (such as trying to pass
> POSIX structure on C11 functions and to avoid inclusion of pthread.h).  The
> idea is to make it possible to share POSIX internal implementation for mostly
> of the code making adjust where only required.

OK.

> Checked with a build for all major ABI (aarch64-linux-gnu, alpha-linux-gnu,
> arm-linux-gnueabi, i386-linux-gnu, ia64-linux-gnu, m68k-linux-gnu,
> microblaze-linux-gnu [1], mips{64}-linux-gnu, nios2-linux-gnu,
> powerpc{64le}-linux-gnu, s390{x}-linux-gnu, sparc{64}-linux-gnu,
> tile{pro,gx}-linux-gnu, and x86_64-linux-gnu).

OK.

> Also ran a full check on aarch64-linux-gnu, x86_64-linux-gnu, i686-linux-gnu,
> arm-linux-gnueabhf, and powerpc64le-linux-gnu.
> 
> 	[BZ #14092]
> 	* conform/data/threads.h-data (cnd_t): New type.
> 	(cnd_init): New function.
> 	(cnd_signal): Likewise.
> 	(cnd_broadcast): Likewise.
> 	(cnd_wait): Likewise.
> 	(cnd_timedwait): Likewise.
> 	(cnd_destroy): Likewise.
> 	* nptl/Makefile (libpthread-routines): Add cnd_broadcast,
> 	cnd_destroy, cnd_init, cnd_signal, cnd_timedwait, and cnd_wait
> 	object.
> 	* nptl/Versions (libpthread) [GLIBC_2.28]: Likewise.
> 	* nptl/cnd_broadcast.c: New file.
> 	* nptl/cnd_destroy.c: Likewise.
> 	* nptl/cnd_init.c: Likewise.
> 	* nptl/cnd_signal.c: Likewise.
> 	* nptl/cnd_timedwait.c: Likewise.
> 	* nptl/cnd_wait.c: Likewise.
> 	* sysdeps/nptl/threads.h (cnd_t): New type.
> 	(cnd_init): New prototype.
> 	(cnd_signa): Likewise.
> 	(cnd_broadcast): Likewise.
> 	(cnd_wait): Likewise.
> 	(cnd_timedwait): Likewise.
> 	(cnd_destroy): Likewise.

This looks good to me.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

> ---
>  ChangeLog                   | 26 ++++++++++++++++++++++++++
>  conform/data/threads.h-data |  8 ++++++++
>  nptl/Makefile               |  3 ++-
>  nptl/Versions               |  3 ++-
>  nptl/cnd_broadcast.c        | 26 ++++++++++++++++++++++++++
>  nptl/cnd_destroy.c          | 26 ++++++++++++++++++++++++++
>  nptl/cnd_init.c             | 33 +++++++++++++++++++++++++++++++++
>  nptl/cnd_signal.c           | 26 ++++++++++++++++++++++++++
>  nptl/cnd_timedwait.c        | 29 +++++++++++++++++++++++++++++
>  nptl/cnd_wait.c             | 27 +++++++++++++++++++++++++++
>  nptl/threads.h              | 34 ++++++++++++++++++++++++++++++++++
>  11 files changed, 239 insertions(+), 2 deletions(-)
>  create mode 100644 nptl/cnd_broadcast.c
>  create mode 100644 nptl/cnd_destroy.c
>  create mode 100644 nptl/cnd_init.c
>  create mode 100644 nptl/cnd_signal.c
>  create mode 100644 nptl/cnd_timedwait.c
>  create mode 100644 nptl/cnd_wait.c

This looks good to me. It looks good to me for 2.28.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
 
> diff --git a/ChangeLog b/ChangeLog
> index 1b1d79e..f92f25a 100644
> --- a/ChangeLog
> +++ b/ChangeLog
> @@ -1,6 +1,32 @@
>  2018-07-21  Adhemerval Zanella  <adhemerval.zanella@linaro.org>
>  
>  	[BZ #14092]
> +	* conform/data/threads.h-data (cnd_t): New type.
> +	(cnd_init): New function.
> +	(cnd_signal): Likewise.
> +	(cnd_broadcast): Likewise.
> +	(cnd_wait): Likewise.
> +	(cnd_timedwait): Likewise.
> +	(cnd_destroy): Likewise.
> +	* nptl/Makefile (libpthread-routines): Add cnd_broadcast,
> +	cnd_destroy, cnd_init, cnd_signal, cnd_timedwait, and cnd_wait
> +	object.
> +	* nptl/Versions (libpthread) [GLIBC_2.28]: Likewise.
> +	* nptl/cnd_broadcast.c: New file.
> +	* nptl/cnd_destroy.c: Likewise.
> +	* nptl/cnd_init.c: Likewise.
> +	* nptl/cnd_signal.c: Likewise.
> +	* nptl/cnd_timedwait.c: Likewise.
> +	* nptl/cnd_wait.c: Likewise.
> +	* sysdeps/nptl/threads.h (cnd_t): New type.
> +	(cnd_init): New prototype.
> +	(cnd_signa): Likewise.
> +	(cnd_broadcast): Likewise.
> +	(cnd_wait): Likewise.
> +	(cnd_timedwait): Likewise.
> +	(cnd_destroy): Likewise.
> +

OK.

> +	[BZ #14092]
>  	* conform/data/threads.h-data (ONCE_FLAG_INIT): New macro.
>  	(once_flag): New type.
>  	(call_once): New function.
> diff --git a/conform/data/threads.h-data b/conform/data/threads.h-data
> index 70b2fe0..d7c562e 100644
> --- a/conform/data/threads.h-data
> +++ b/conform/data/threads.h-data
> @@ -16,6 +16,7 @@ type thrd_t
>  type thrd_start_t
>  type mtx_t
>  type once_flag
> +type cnd_t
>  
>  function int thrd_create (thrd_t*, thrd_start_t, void*)
>  function int thrd_equal (thrd_t, thrd_t)
> @@ -35,6 +36,13 @@ function void mtx_destroy (mtx_t*)
>  
>  function void call_once (once_flag*, void (*)(void))
>  
> +function int cnd_init (cnd_t*)
OK.

> +function int cnd_signal (cnd_t*)
OK.

> +function int cnd_broadcast (cnd_t*)
OK.

> +function int cnd_wait (cnd_t*, mtx_t*)
OK.

> +function int cnd_timedwait (cnd_t*, mtx_t*, const struct timespec*)
OK.

> +function void cnd_destroy (cnd_t*)
OK.

> +
>  #include "time.h-data"
>  
>  #endif
> diff --git a/nptl/Makefile b/nptl/Makefile
> index d55d24b..0864aee 100644
> --- a/nptl/Makefile
> +++ b/nptl/Makefile
> @@ -143,7 +143,8 @@ libpthread-routines = nptl-init nptlfreeres vars events version pt-interp \
>  		      pthread_setattr_default_np pthread_getattr_default_np \
>  		      thrd_create thrd_detach thrd_exit thrd_join \
>  		      mtx_destroy mtx_init mtx_lock mtx_timedlock \
> -		      mtx_trylock mtx_unlock call_once
> +		      mtx_trylock mtx_unlock call_once cnd_broadcast \
> +		      cnd_destroy cnd_init cnd_signal cnd_timedwait cnd_wait

OK. 6 interfaces.

>  #		      pthread_setuid pthread_seteuid pthread_setreuid \
>  #		      pthread_setresuid \
>  #		      pthread_setgid pthread_setegid pthread_setregid \
> diff --git a/nptl/Versions b/nptl/Versions
> index 0fdba18..9c38d67 100644
> --- a/nptl/Versions
> +++ b/nptl/Versions
> @@ -273,7 +273,8 @@ libpthread {
>    GLIBC_2.28 {
>      thrd_create; thrd_detach; thrd_exit; thrd_join;
>      mtx_init; mtx_lock; mtx_timedlock; mtx_trylock; mtx_unlock; mtx_destroy;
> -    call_once;
> +    call_once; cnd_broadcast; cnd_destroy; cnd_init; cnd_signal;
> +    cnd_timedwait; cnd_wait;

OK. 6.

>    }
>  
>    GLIBC_PRIVATE {
> diff --git a/nptl/cnd_broadcast.c b/nptl/cnd_broadcast.c
> new file mode 100644
> index 0000000..889f88e
> --- /dev/null
> +++ b/nptl/cnd_broadcast.c
> @@ -0,0 +1,26 @@
> +/* C11 thread conditional broadcast implementation.
> +   Copyright (C) 2018 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/>.  */
> +
> +#include "thrd_priv.h"
> +
> +int
> +cnd_broadcast (cnd_t *cond)
> +{
> +  int err_code = __pthread_cond_broadcast ((pthread_cond_t*) cond);
> +  return thrd_err_map (err_code);
> +}

OK.

> diff --git a/nptl/cnd_destroy.c b/nptl/cnd_destroy.c
> new file mode 100644
> index 0000000..37df9e9
> --- /dev/null
> +++ b/nptl/cnd_destroy.c
> @@ -0,0 +1,26 @@
> +/* C11 threads conditional destroy implementation.
> +   Copyright (C) 2018 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/>.  */
> +
> +#include "thrd_priv.h"
> +#include "pthreadP.h"
> +
> +void
> +cnd_destroy (cnd_t *cond)
> +{
> +  __pthread_cond_destroy ((pthread_cond_t *) cond);
> +}

OK.

> diff --git a/nptl/cnd_init.c b/nptl/cnd_init.c
> new file mode 100644
> index 0000000..13f0f80
> --- /dev/null
> +++ b/nptl/cnd_init.c
> @@ -0,0 +1,33 @@
> +/* C11 thread conditional initialization implementation.
> +   Copyright (C) 2018 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/>.  */
> +
> +#include <stdalign.h>
> +
> +#include "thrd_priv.h"
> +
> +int
> +cnd_init (cnd_t *cond)
> +{
> +  _Static_assert (sizeof (cnd_t) == sizeof (pthread_cond_t),
> +		  "(sizeof (cnd_t) != sizeof (pthread_cond_t)");
> +  _Static_assert (alignof (cnd_t) == alignof (pthread_cond_t),
> +		  "alignof (cnd_t) != alignof (pthread_cond_t)");

OK.

> +
> +  int err_code = __pthread_cond_init ((pthread_cond_t *)cond, NULL);
> +  return thrd_err_map (err_code);

OK.

> +}
> diff --git a/nptl/cnd_signal.c b/nptl/cnd_signal.c
> new file mode 100644
> index 0000000..8ae650b
> --- /dev/null
> +++ b/nptl/cnd_signal.c
> @@ -0,0 +1,26 @@
> +/* C11 threads conditional signal implementation.
> +   Copyright (C) 2018 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/>.  */
> +
> +#include "thrd_priv.h"
> +
> +int
> +cnd_signal (cnd_t *cond)
> +{
> +  int err_code = __pthread_cond_signal ((pthread_cond_t *) cond);
> +  return thrd_err_map (err_code);
> +}

OK.

> diff --git a/nptl/cnd_timedwait.c b/nptl/cnd_timedwait.c
> new file mode 100644
> index 0000000..75358fe
> --- /dev/null
> +++ b/nptl/cnd_timedwait.c
> @@ -0,0 +1,29 @@
> +/* C11 threads conditional timed wait implementation.
> +   Copyright (C) 2018 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/>.  */
> +
> +#include "thrd_priv.h"
> +
> +int
> +cnd_timedwait (cnd_t *restrict cond, mtx_t *restrict mutex,
> +	       const struct timespec* restrict time_point)
> +{
> +  int err_code = __pthread_cond_timedwait ((pthread_cond_t *) cond,
> +					   (pthread_mutex_t *) mutex,
> +					   time_point);
> +  return thrd_err_map (err_code);

OK.

> +}
> diff --git a/nptl/cnd_wait.c b/nptl/cnd_wait.c
> new file mode 100644
> index 0000000..727d9bb
> --- /dev/null
> +++ b/nptl/cnd_wait.c
> @@ -0,0 +1,27 @@
> +/* C11 threads conditional wait implementaiton.
> +   Copyright (C) 2018 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/>.  */
> +
> +#include "thrd_priv.h"
> +
> +int
> +cnd_wait (cnd_t *cond, mtx_t *mutex)
> +{
> +  int err_code = __pthread_cond_wait ((pthread_cond_t *) cond,
> +				      (pthread_mutex_t *) mutex);
> +  return thrd_err_map (err_code);

OK.

> +}
> diff --git a/nptl/threads.h b/nptl/threads.h
> index 32f7cf8..e46b1b7 100644
> --- a/nptl/threads.h
> +++ b/nptl/threads.h
> @@ -60,6 +60,12 @@ typedef union
>    long int __align __LOCK_ALIGNMENT;
>  } mtx_t;
>  
> +typedef union
> +{
> +  char __size[__SIZEOF_PTHREAD_COND_T];
> +  __extension__ long long int __align __LOCK_ALIGNMENT;
> +} cnd_t;

OK.

> +
>  /* Threads functions.  */
>  
>  /* Create a new thread executing the function __FUNC.  Arguments for __FUNC
> @@ -140,6 +146,34 @@ extern void mtx_destroy (mtx_t *__mutex);
>     All calls must be made with the same __FLAGS object.  */
>  extern void call_once (once_flag *__flag, void (*__func)(void));
>  
> +
> +/* Condition variable functions.  */
> +
> +/* Initialize new condition variable pointed by __COND.  */
> +extern int cnd_init (cnd_t *__cond);
> +
> +/* Unblock one thread that currently waits on condition variable pointed
> +   by __COND.  */
> +extern int cnd_signal (cnd_t *__cond);
> +
> +/* Unblock all threads currently waiting on condition variable pointed by
> +   __COND.  */
> +extern int cnd_broadcast (cnd_t *__cond);
> +
> +/* Block current thread on the condition variable pointed by __COND.  */
> +extern int cnd_wait (cnd_t *__cond, mtx_t *__mutex);
> +
> +/* Block current thread on the condition variable until condition variable
> +   pointed by __COND is signaled or time pointed by __TIME_POINT is
> +   reached.  */
> +extern int cnd_timedwait (cnd_t *__restrict __cond,
> +			  mtx_t *__restrict __mutex,
> +			  const struct timespec *__restrict __time_point);
> +
> +/* Destroy condition variable pointed by __cond and free all of its
> +   resources.  */
> +extern void cnd_destroy (cnd_t *__COND);

OK.

> +
>  __END_DECLS
>  
>  #endif /* _THREADS_H */
> 

Cheers,
Carlos.