[PATCH v2 1/2] aio: Provide Linux specific copy of aio_suspend.c
Adhemerval Zanella
adhemerval.zanella@linaro.org
Tue Nov 17 14:27:20 GMT 2020
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
> 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 = ¶m->requestlist[cnt]->waiting;
> + while (*listp != NULL && *listp != ¶m->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)
>
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