glibc/sysdeps/pthread/aio_suspend.c
Zack Weinberg 4a39c34c4f Change most internal uses of __gettimeofday to __clock_gettime.
Since gettimeofday will shortly be implemented in terms of
clock_gettime on all platforms, internal code should use clock_gettime
directly; in addition to removing a layer of indirection, this will
allow us to remove the PLT-bypass gunk for gettimeofday.  (We can't
quite do that yet, but it'll be coming later in this patch series.)
In many cases, the changed code does fewer conversions.

The changed code always assumes __clock_gettime (CLOCK_REALTIME)
cannot fail.  Most of the call sites were assuming gettimeofday could
not fail, but a few places were checking for errors.  POSIX says
clock_gettime can only fail if the clock constant is invalid or
unsupported, and CLOCK_REALTIME is the one and only clock constant
that's required to be supported.  For consistency I grepped the entire
source tree for any other places that checked for errors from
__clock_gettime (CLOCK_REALTIME), found one, and changed it too.

(For the record, POSIX also says gettimeofday can never fail.)

(It would be nice if we could declare that GNU systems will always
support CLOCK_MONOTONIC as well as CLOCK_REALTIME; there are several
places where we are using CLOCK_REALTIME where _MONOTONIC would be
more appropriate, and/or trying to use _MONOTONIC and then falling
back to _REALTIME.  But the Hurd doesn't support CLOCK_MONOTONIC yet,
and it looks like adding it would involve substantial changes to
gnumach's internals and API.  Oh well.)

A few Hurd-specific files were changed to use __host_get_time instead
of __clock_gettime, as this seemed tidier.  We also assume this cannot
fail.  Skimming the code in gnumach leads me to believe the only way
it could fail is if __mach_host_self also failed, and our
Hurd-specific code consistently assumes that can't happen, so I'm
going with that.

With the exception of support/support_test_main.c, test cases are not
modified, mainly because I didn't want to have to figure out which
test cases were testing gettimeofday specifically.

The definition of GETTIME in sysdeps/generic/memusage.h had a typo and
was not reading tv_sec at all.  I fixed this.  It appears nobody has been
generating malloc traces on a machine that doesn't have a superseding
definition.

There are a whole bunch of places where the code could be simplified
by factoring out timespec subtraction and/or comparison logic, but I
want to keep this patch as mechanical as possible.

Checked on x86_64-linux-gnu, i686-linux-gnu, powerpc64le-linux-gnu,
powerpc64-linux-gnu, powerpc-linux-gnu, and aarch64-linux-gnu.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: Lukasz Majewski <lukma@denx.de>
2019-10-30 17:04:10 -03:00

254 lines
6.5 KiB
C

/* Suspend until termination of a requests.
Copyright (C) 1997-2019 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)