Re: [PATCH v2 1/2] aio: Provide Linux specific copy of aio_suspend.c

[Lukasz Majewski <lukma@denx.de>]

[-- Attachment #1: Type: text/plain, Size: 11817 bytes --]

Hi Adhemerval,

> On 14/11/2020 18:45, Lukasz Majewski wrote:
> > This patch is a preparatory work, to provide 64 bit time support
> > to aio_suspend.c, which would avoid build breaks on the HURD
> > (i686-gnu) port, as it is not supporting 64 bit version of
> > __pthread_cond_timedwait64.
> > 
> > The file sysdeps/unix/sysv/linux/aio_suspend.c is the exact copy of
> > ./sysdeps/pthread/aio_suspend.c
> > 
> > ---
> > Changes for v2:
> > - Rephase the commit message
> > ---  
> 
> I am not very found of this code duplication and the Linux version
> does not need !DONT_NEED_AIO_MISC_COND, since nptl/aio_misc.h will
> always define to 1.
> 
> I think it would be better to move the sysdeps/pthread/aio_suspend.c
> to a parametrized implementation
> (sysdeps/pthread/aio_suspend_skeleton.c or something) where the
> internal types and function should be defined (similar to the
> dynamic_array.h) something like:
> 
>    94 #ifdef DONT_NEED_AIO_MISC_COND
>    95 static int
>    96 __attribute__ ((noinline))
>    97 do_aio_misc_wait (unsigned int *cntr, const TIMESPEC_STRUCT
> *timeout) 98 {
>    99   int result = 0;
>   100 
>   101   AIO_MISC_WAIT_MACRO (result, *cntr, timeout, 1);
>   102 
>   103   return result;
>   104 }
>   105 #endif
>   106 
>   107 int
>   108 AIO_SUSPEND (const struct aiocb *const list[], int nent,
>   109              const TIMESPEC_STRUCT *timeout)
>   110 {
>   111   if (__glibc_unlikely (nent < 0))
>   112     {
>   113       __set_errno (EINVAL);
>   114       return -1;
>   115     }
> 
> And then generic sysdeps/pthread/aio_suspend.c will define the types
> and include the parametrized implementation:
> 
>   #define TIMESPEC_STRUCT struct timespec
>   #define AIO_SUSPEND     aio_suspend
>   #include <sysdeps/pthread/aio_suspend_skeleton.c>
> 
> 
> The Linux implementation sysdeps/unix/sysv/linux/aio_suspend.c then
> can do:
> 
>   
>   #if __TIMESIZE != 64
>   #  define TIMESPEC_STRUCT         struct __timespec64
>   #  define AIO_SUSPEND             __aio_suspend64_time64
>   #  define AIO_MISC_WAIT_MACRO     AIO_MISC_WAIT64
>   #else
>   #  define TIMESPEC_STRUCT         struct timespec
>   #  define AIO_SUSPEND             aio_suspend
>   #  define AIO_MISC_WAIT_MACRO     AIO_MISC_WAIT
>   #endif 
>   #include <sysdeps/pthread/aio_suspend_skeleton.c>
> 
>   #if __TIMESIZE != 64
>   librt_hidden_def (__aio_suspend_time64)
>   
>   int
>   __aio_suspend (const struct aiocb *const list[], int nent,
>                   const struct timespec *timeout)
>   {
>     struct __timespec64 ts64;
>     if (timeout != NULL)
>       ts64 = valid_timespec_to_timespec64 (*timeout);
>     return __aio_suspend_time64 (list, nent, timeout != NULL ? &ts64
> : NULL); }
>   #endif
> 

Ok. This shall help with avoiding code duplication.

> 
> >  sysdeps/unix/sysv/linux/aio_suspend.c | 253
> > ++++++++++++++++++++++++++ 1 file changed, 253 insertions(+)
> >  create mode 100644 sysdeps/unix/sysv/linux/aio_suspend.c
> > 
> > diff --git a/sysdeps/unix/sysv/linux/aio_suspend.c
> > b/sysdeps/unix/sysv/linux/aio_suspend.c new file mode 100644
> > index 0000000000..ad03f13558
> > --- /dev/null
> > +++ b/sysdeps/unix/sysv/linux/aio_suspend.c
> > @@ -0,0 +1,253 @@
> > +/* Suspend until termination of a requests.
> > +   Copyright (C) 1997-2020 Free Software Foundation, Inc.
> > +   This file is part of the GNU C Library.
> > +   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
> > +
> > +   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/>.  */
> > +
> > +
> > +/* We use an UGLY hack to prevent gcc from finding us cheating.
> > The
> > +   implementations of aio_suspend and aio_suspend64 are identical
> > and so
> > +   we want to avoid code duplication by using aliases.  But gcc
> > sees
> > +   the different parameter lists and prints a warning.  We define
> > here
> > +   a function so that aio_suspend64 has no prototype.  */
> > +#define aio_suspend64 XXX
> > +#include <aio.h>
> > +/* And undo the hack.  */
> > +#undef aio_suspend64
> > +
> > +#include <assert.h>
> > +#include <errno.h>
> > +#include <stdbool.h>
> > +#include <stdlib.h>
> > +#include <sys/time.h>
> > +
> > +#include <libc-lock.h>
> > +#include <aio_misc.h>
> > +
> > +
> > +struct clparam
> > +{
> > +  const struct aiocb *const *list;
> > +  struct waitlist *waitlist;
> > +  struct requestlist **requestlist;
> > +#ifndef DONT_NEED_AIO_MISC_COND
> > +  pthread_cond_t *cond;
> > +#endif
> > +  int nent;
> > +};
> > +
> > +
> > +static void
> > +cleanup (void *arg)
> > +{
> > +#ifdef DONT_NEED_AIO_MISC_COND
> > +  /* Acquire the mutex.  If pthread_cond_*wait is used this would
> > +     happen implicitly.  */
> > +  pthread_mutex_lock (&__aio_requests_mutex);
> > +#endif
> > +
> > +  const struct clparam *param = (const struct clparam *) arg;
> > +
> > +  /* Now remove the entry in the waiting list for all requests
> > +     which didn't terminate.  */
> > +  int cnt = param->nent;
> > +  while (cnt-- > 0)
> > +    if (param->list[cnt] != NULL
> > +	&& param->list[cnt]->__error_code == EINPROGRESS)
> > +      {
> > +	struct waitlist **listp;
> > +
> > +	assert (param->requestlist[cnt] != NULL);
> > +
> > +	/* There is the chance that we cannot find our entry
> > anymore. This
> > +	   could happen if the request terminated and restarted
> > again.  */
> > +	listp = &param->requestlist[cnt]->waiting;
> > +	while (*listp != NULL && *listp != &param->waitlist[cnt])
> > +	  listp = &(*listp)->next;
> > +
> > +	if (*listp != NULL)
> > +	  *listp = (*listp)->next;
> > +      }
> > +
> > +#ifndef DONT_NEED_AIO_MISC_COND
> > +  /* Release the conditional variable.  */
> > +  (void) pthread_cond_destroy (param->cond);
> > +#endif
> > +
> > +  /* Release the mutex.  */
> > +  pthread_mutex_unlock (&__aio_requests_mutex);
> > +}
> > +
> > +#ifdef DONT_NEED_AIO_MISC_COND
> > +static int
> > +__attribute__ ((noinline))
> > +do_aio_misc_wait (unsigned int *cntr, const struct timespec
> > *timeout) +{
> > +  int result = 0;
> > +
> > +  AIO_MISC_WAIT (result, *cntr, timeout, 1);
> > +
> > +  return result;
> > +}
> > +#endif
> > +
> > +int
> > +aio_suspend (const struct aiocb *const list[], int nent,
> > +	     const struct timespec *timeout)
> > +{
> > +  if (__glibc_unlikely (nent < 0))
> > +    {
> > +      __set_errno (EINVAL);
> > +      return -1;
> > +    }
> > +
> > +  struct waitlist waitlist[nent];
> > +  struct requestlist *requestlist[nent];
> > +#ifndef DONT_NEED_AIO_MISC_COND
> > +  pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
> > +#endif
> > +  int cnt;
> > +  bool any = false;
> > +  int result = 0;
> > +  unsigned int cntr = 1;
> > +
> > +  /* Request the mutex.  */
> > +  pthread_mutex_lock (&__aio_requests_mutex);
> > +
> > +  /* There is not yet a finished request.  Signal the request that
> > +     we are working for it.  */
> > +  for (cnt = 0; cnt < nent; ++cnt)
> > +    if (list[cnt] != NULL)
> > +      {
> > +	if (list[cnt]->__error_code == EINPROGRESS)
> > +	  {
> > +	    requestlist[cnt] = __aio_find_req ((aiocb_union *)
> > list[cnt]); +
> > +	    if (requestlist[cnt] != NULL)
> > +	      {
> > +#ifndef DONT_NEED_AIO_MISC_COND
> > +		waitlist[cnt].cond = &cond;
> > +#endif
> > +		waitlist[cnt].result = NULL;
> > +		waitlist[cnt].next = requestlist[cnt]->waiting;
> > +		waitlist[cnt].counterp = &cntr;
> > +		waitlist[cnt].sigevp = NULL;
> > +		requestlist[cnt]->waiting = &waitlist[cnt];
> > +		any = true;
> > +	      }
> > +	    else
> > +	      /* We will never suspend.  */
> > +	      break;
> > +	  }
> > +	else
> > +	  /* We will never suspend.  */
> > +	  break;
> > +      }
> > +
> > +
> > +  /* Only if none of the entries is NULL or finished to be wait.
> > */
> > +  if (cnt == nent && any)
> > +    {
> > +      struct clparam clparam =
> > +	{
> > +	  .list = list,
> > +	  .waitlist = waitlist,
> > +	  .requestlist = requestlist,
> > +#ifndef DONT_NEED_AIO_MISC_COND
> > +	  .cond = &cond,
> > +#endif
> > +	  .nent = nent
> > +	};
> > +
> > +      pthread_cleanup_push (cleanup, &clparam);
> > +
> > +#ifdef DONT_NEED_AIO_MISC_COND
> > +      result = do_aio_misc_wait (&cntr, timeout);
> > +#else
> > +      if (timeout == NULL)
> > +	result = pthread_cond_wait (&cond, &__aio_requests_mutex);
> > +      else
> > +	{
> > +	  /* We have to convert the relative timeout value into an
> > +	     absolute time value with pthread_cond_timedwait
> > expects.  */
> > +	  struct timespec now;
> > +	  struct timespec abstime;
> > +
> > +	  __clock_gettime (CLOCK_REALTIME, &now);
> > +	  abstime.tv_nsec = timeout->tv_nsec + now.tv_nsec;
> > +	  abstime.tv_sec = timeout->tv_sec + now.tv_sec;
> > +	  if (abstime.tv_nsec >= 1000000000)
> > +	    {
> > +	      abstime.tv_nsec -= 1000000000;
> > +	      abstime.tv_sec += 1;
> > +	    }
> > +
> > +	  result = pthread_cond_timedwait (&cond,
> > &__aio_requests_mutex,
> > +					   &abstime);
> > +	}
> > +#endif
> > +
> > +      pthread_cleanup_pop (0);
> > +    }
> > +
> > +  /* Now remove the entry in the waiting list for all requests
> > +     which didn't terminate.  */
> > +  while (cnt-- > 0)
> > +    if (list[cnt] != NULL && list[cnt]->__error_code ==
> > EINPROGRESS)
> > +      {
> > +	struct waitlist **listp;
> > +
> > +	assert (requestlist[cnt] != NULL);
> > +
> > +	/* There is the chance that we cannot find our entry
> > anymore. This
> > +	   could happen if the request terminated and restarted
> > again.  */
> > +	listp = &requestlist[cnt]->waiting;
> > +	while (*listp != NULL && *listp != &waitlist[cnt])
> > +	  listp = &(*listp)->next;
> > +
> > +	if (*listp != NULL)
> > +	  *listp = (*listp)->next;
> > +      }
> > +
> > +#ifndef DONT_NEED_AIO_MISC_COND
> > +  /* Release the conditional variable.  */
> > +  if (__glibc_unlikely (pthread_cond_destroy (&cond) != 0))
> > +    /* This must never happen.  */
> > +    abort ();
> > +#endif
> > +
> > +  if (result != 0)
> > +    {
> > +#ifndef DONT_NEED_AIO_MISC_COND
> > +      /* An error occurred.  Possibly it's ETIMEDOUT.  We have to
> > translate
> > +	 the timeout error report of `pthread_cond_timedwait' to
> > the
> > +	 form expected from `aio_suspend'.  */
> > +      if (result == ETIMEDOUT)
> > +	__set_errno (EAGAIN);
> > +      else
> > +#endif
> > +	__set_errno (result);
> > +
> > +      result = -1;
> > +    }
> > +
> > +  /* Release the mutex.  */
> > +  pthread_mutex_unlock (&__aio_requests_mutex);
> > +
> > +  return result;
> > +}
> > +
> > +weak_alias (aio_suspend, aio_suspend64)
> >   




Best regards,

Lukasz Majewski

--

DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma@denx.de

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 488 bytes --]