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Remove signal handling for nanosleep (bug 16364) 

Linux 2.6.32 and forward do not show the issue regarding SysV SIGCHLD
vs. SIG_IGN for nanosleep which make it feasible to use it for sleep
implementation without requiring any hacking to handle the spurious
wake up.  The issue is likely being fixed before 2.6 and git
history [1] [2].

This patch simplifies the sleep code to call nanosleep directly by
using the posix default version.  It also removes the early cancellation
tests for zero argument, since nanosleep will handle cancellation
in this case.

[1] https://lkml.org/lkml/2004/11/25/5
[2] https://lkml.org/lkml/2003/11/8/50

Checked on x86_64, ppc64le, and aarch64.

	[BZ #16364]
	* sysdeps/unix/sysv/linux/sleep.c: Remove file
	* sysdeps/posix/sleep.c (__sleep): Simplify cancellation handling.
This commit is contained in:
Adhemerval Zanella 2015-11-08 20:06:42 -02:00 committed by Adhemerval Zanella
parent 31cf39421b
commit 8c873bf019
3 changed files with 6 additions and 158 deletions
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6
ChangeLog
View File

@ -1,3 +1,9 @@
2015-11-20 Adhemerval Zanella <adhemerval.zanella@linaro.org>
[BZ #16364]
* sysdeps/unix/sysv/linux/sleep.c: Remove file.
* sysdeps/posix/sleep.c (__sleep): Simplify cancellation handling.
2015-11-20 Stefan Liebler <stli@linux.vnet.ibm.com>
* sysdeps/s390/fpu/bits/mathinline.h:

9
sysdeps/posix/sleep.c
View File

@ -32,15 +32,6 @@
unsigned int
__sleep (unsigned int seconds)
{
/* This is not necessary but some buggy programs depend on it. */
if (__glibc_unlikely (seconds == 0))
{
#ifdef CANCELLATION_P
CANCELLATION_P (THREAD_SELF);
#endif
return 0;
}
int save_errno = errno;
const unsigned int max

149
sysdeps/unix/sysv/linux/sleep.c
View File

@ -1,149 +0,0 @@
/* Implementation of the POSIX sleep function using nanosleep.
Copyright (C) 1996-2015 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
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 <errno.h>
#include <time.h>
#include <signal.h>
#include <string.h> /* For the real memset prototype. */
#include <unistd.h>
#include <sys/param.h>
#include <nptl/pthreadP.h>
#if 0
static void
cl (void *arg)
{
(void) __sigprocmask (SIG_SETMASK, arg, (sigset_t *) NULL);
}
#endif
/* We are going to use the `nanosleep' syscall of the kernel. But the
kernel does not implement the stupid SysV SIGCHLD vs. SIG_IGN
behaviour for this syscall. Therefore we have to emulate it here. */
unsigned int
__sleep (unsigned int seconds)
{
const unsigned int max
= (unsigned int) (((unsigned long int) (~((time_t) 0))) >> 1);
struct timespec ts;
sigset_t set, oset;
unsigned int result;
/* This is not necessary but some buggy programs depend on this. */
if (__glibc_unlikely (seconds == 0))
{
#ifdef CANCELLATION_P
CANCELLATION_P (THREAD_SELF);
#endif
return 0;
}
ts.tv_sec = 0;
ts.tv_nsec = 0;
again:
if (sizeof (ts.tv_sec) <= sizeof (seconds))
{
/* Since SECONDS is unsigned assigning the value to .tv_sec can
overflow it. In this case we have to wait in steps. */
ts.tv_sec += MIN (seconds, max);
seconds -= (unsigned int) ts.tv_sec;
}
else
{
ts.tv_sec = (time_t) seconds;
seconds = 0;
}
/* Linux will wake up the system call, nanosleep, when SIGCHLD
arrives even if SIGCHLD is ignored. We have to deal with it
in libc. We block SIGCHLD first. */
__sigemptyset (&set);
__sigaddset (&set, SIGCHLD);
if (__sigprocmask (SIG_BLOCK, &set, &oset))
return -1;
/* If SIGCHLD is already blocked, we don't have to do anything. */
if (!__sigismember (&oset, SIGCHLD))
{
int saved_errno;
struct sigaction oact;
__sigemptyset (&set);
__sigaddset (&set, SIGCHLD);
/* We get the signal handler for SIGCHLD. */
if (__sigaction (SIGCHLD, (struct sigaction *) NULL, &oact) < 0)
{
saved_errno = errno;
/* Restore the original signal mask. */
(void) __sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL);
__set_errno (saved_errno);
return -1;
}
/* Note the sleep() is a cancellation point. But since we call
nanosleep() which itself is a cancellation point we do not
have to do anything here. */
if (oact.sa_handler == SIG_IGN)
{
//__libc_cleanup_push (cl, &oset);
/* We should leave SIGCHLD blocked. */
while (1)
{
result = __nanosleep (&ts, &ts);
if (result != 0 || seconds == 0)
break;
if (sizeof (ts.tv_sec) <= sizeof (seconds))
{
ts.tv_sec = MIN (seconds, max);
seconds -= (unsigned int) ts.tv_nsec;
}
}
//__libc_cleanup_pop (0);
saved_errno = errno;
/* Restore the original signal mask. */
(void) __sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL);
__set_errno (saved_errno);
goto out;
}
/* We should unblock SIGCHLD. Restore the original signal mask. */
(void) __sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL);
}
result = __nanosleep (&ts, &ts);
if (result == 0 && seconds != 0)
goto again;
out:
if (result != 0)
/* Round remaining time. */
result = seconds + (unsigned int) ts.tv_sec + (ts.tv_nsec >= 500000000L);
return result;
}
weak_alias (__sleep, sleep)