freebsd-nq/lib/libthr/thread/thr_syscalls.c
Mike Makonnen 4cd18a22d5 Make libthr async-signal-safe without costly signal masking. The guidlines I
followed are: Only 3 functions (pthread_cancel, pthread_setcancelstate,
pthread_setcanceltype) are required to be async-signal-safe by POSIX. None of
the rest of the pthread api is required to be async-signal-safe. This means
that only the three mentioned functions are safe to use from inside
signal handlers.
However, there are certain system/libc calls that are
cancellation points that a caller may call from within a signal handler,
and since they are cancellation points calls have to be made into libthr
to test for cancellation and exit the thread if necessary. So, the
cancellation test and thread exit code paths must be async-signal-safe
as well. A summary of the changes follows:

o Almost all of the code paths that masked signals, as well as locking the
  pthread structure now lock only the pthread structure.
o Signals are masked (and left that way) as soon as a thread enters
  pthread_exit().
o The active and dead threads locks now explicitly require that signals
  are masked.
o Access to the isdead field of the pthread structure is protected by both
  the active and dead list locks for writing. Either one is sufficient for
  reading.
o The thread state and type fields have been combined into one three-state
  switch to make it easier to read without requiring a lock. It doesn't need
  a lock for writing (and therefore for reading either) because only the
  current thread can write to it and it is an integer value.
o The thread state field of the pthread structure has been eliminated. It
  was an unnecessary field that mostly duplicated the flags field, but
  required additional locking that would make a lot more code paths require
  signal masking. Any truly unique values (such as PS_DEAD) have been
  reborn as separate members of the pthread structure.
o Since the mutex and condvar pthread functions are not async-signal-safe
  there is no need to muck about with the wait queues when handling
  a signal ...
o ... which also removes the need for wrapping signal handlers and sigaction(2).
o The condvar and mutex async-cancellation code had to be revised as a result
  of some of these changes, which resulted in semi-unrelated changes which
  would have been difficult to work on as a separate commit, so they are
  included as well.

The only part of the changes I am worried about is related to locking for
the pthread joining fields. But, I will take a closer look at them once this
mega-patch is committed.
2004-05-20 12:06:16 +00:00

445 lines
9.8 KiB
C

/*
* Copyright (c) 2000 Jason Evans <jasone@freebsd.org>.
* Copyright (c) 2002 Daniel M. Eischen <deischen@freebsd.org>
* Copyright (c) 2003 Jeff Roberson <jeff@freebsd.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice(s), this list of conditions and the following disclaimer as
* the first lines of this file unmodified other than the possible
* addition of one or more copyright notices.
* 2. Redistributions in binary form must reproduce the above copyright
* notice(s), this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
* OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $FreeBSD$
*/
/*
* Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by John Birrell.
* 4. Neither the name of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
#include <sys/cdefs.h>
#include <sys/fcntl.h>
#include <sys/mman.h>
#include <sys/param.h>
#include <sys/select.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <sys/wait.h>
#include <aio.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <poll.h>
#include <pthread.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>
#include "thr_private.h"
extern int __creat(const char *, mode_t);
extern int __sleep(unsigned int);
extern int __sys_nanosleep(const struct timespec *, struct timespec *);
extern int __sys_select(int, fd_set *, fd_set *, fd_set *, struct timeval *);
extern int __sys_sigaction(int, const struct sigaction *, struct sigaction *);
extern int __system(const char *);
extern int __tcdrain(int);
extern pid_t __wait(int *);
extern pid_t __sys_wait4(pid_t, int *, int, struct rusage *);
extern pid_t __waitpid(pid_t, int *, int);
__weak_reference(_aio_suspend, aio_suspend);
int
_aio_suspend(const struct aiocb * const iocbs[], int niocb, const struct
timespec *timeout)
{
int ret;
_thread_enter_cancellation_point();
ret = __sys_aio_suspend(iocbs, niocb, timeout);
_thread_leave_cancellation_point();
return ret;
}
__weak_reference(_close, close);
int
_close(int fd)
{
int ret;
_thread_enter_cancellation_point();
ret = __sys_close(fd);
_thread_leave_cancellation_point();
return ret;
}
__weak_reference(_creat, creat);
int
_creat(const char *path, mode_t mode)
{
int ret;
_thread_enter_cancellation_point();
ret = __creat(path, mode);
_thread_leave_cancellation_point();
return ret;
}
__weak_reference(_fcntl, fcntl);
int
_fcntl(int fd, int cmd,...)
{
int ret;
va_list ap;
_thread_enter_cancellation_point();
va_start(ap, cmd);
switch (cmd) {
case F_DUPFD:
case F_SETFD:
case F_SETFL:
ret = __sys_fcntl(fd, cmd, va_arg(ap, int));
break;
case F_GETFD:
case F_GETFL:
ret = __sys_fcntl(fd, cmd);
break;
default:
ret = __sys_fcntl(fd, cmd, va_arg(ap, void *));
}
va_end(ap);
_thread_leave_cancellation_point();
return ret;
}
__weak_reference(_fsync, fsync);
int
_fsync(int fd)
{
int ret;
_thread_enter_cancellation_point();
ret = __sys_fsync(fd);
_thread_leave_cancellation_point();
return ret;
}
__weak_reference(_msync, msync);
int
_msync(void *addr, size_t len, int flags)
{
int ret;
_thread_enter_cancellation_point();
ret = __sys_msync(addr, len, flags);
_thread_leave_cancellation_point();
return ret;
}
__weak_reference(_nanosleep, nanosleep);
int
_nanosleep(const struct timespec * time_to_sleep, struct timespec *
time_remaining)
{
int ret;
_thread_enter_cancellation_point();
ret = __sys_nanosleep(time_to_sleep, time_remaining);
_thread_leave_cancellation_point();
return ret;
}
__weak_reference(_open, open);
int
_open(const char *path, int flags,...)
{
int ret;
int mode = 0;
va_list ap;
_thread_enter_cancellation_point();
/* Check if the file is being created: */
if (flags & O_CREAT) {
/* Get the creation mode: */
va_start(ap, flags);
mode = va_arg(ap, int);
va_end(ap);
}
ret = __sys_open(path, flags, mode);
_thread_leave_cancellation_point();
return ret;
}
__weak_reference(_poll, poll);
int
_poll(struct pollfd *fds, unsigned int nfds, int timeout)
{
int ret;
_thread_enter_cancellation_point();
ret = __sys_poll(fds, nfds, timeout);
_thread_leave_cancellation_point();
return ret;
}
extern int __pselect(int count, fd_set *rfds, fd_set *wfds, fd_set *efds,
const struct timespec *timo, const sigset_t *mask);
int
pselect(int count, fd_set *rfds, fd_set *wfds, fd_set *efds,
const struct timespec *timo, const sigset_t *mask)
{
int ret;
_thread_enter_cancellation_point();
ret = __pselect(count, rfds, wfds, efds, timo, mask);
_thread_leave_cancellation_point();
return (ret);
}
__weak_reference(_raise, raise);
int
_raise(int sig)
{
int error;
error = pthread_kill(pthread_self(), sig);
if (error != 0) {
errno = error;
error = -1;
}
return (error);
}
__weak_reference(_read, read);
ssize_t
_read(int fd, void *buf, size_t nbytes)
{
ssize_t ret;
_thread_enter_cancellation_point();
ret = __sys_read(fd, buf, nbytes);
_thread_leave_cancellation_point();
return ret;
}
__weak_reference(_readv, readv);
ssize_t
_readv(int fd, const struct iovec *iov, int iovcnt)
{
ssize_t ret;
_thread_enter_cancellation_point();
ret = __sys_readv(fd, iov, iovcnt);
_thread_leave_cancellation_point();
return ret;
}
__weak_reference(_select, select);
int
_select(int numfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
struct timeval *timeout)
{
int ret;
_thread_enter_cancellation_point();
ret = __sys_select(numfds, readfds, writefds, exceptfds, timeout);
_thread_leave_cancellation_point();
return ret;
}
__weak_reference(_sleep, sleep);
unsigned int
_sleep(unsigned int seconds)
{
unsigned int ret;
_thread_enter_cancellation_point();
ret = __sleep(seconds);
_thread_leave_cancellation_point();
return ret;
}
__weak_reference(_system, system);
int
_system(const char *string)
{
int ret;
_thread_enter_cancellation_point();
ret = __system(string);
_thread_leave_cancellation_point();
return ret;
}
__weak_reference(_tcdrain, tcdrain);
int
_tcdrain(int fd)
{
int ret;
_thread_enter_cancellation_point();
ret = __tcdrain(fd);
_thread_leave_cancellation_point();
return ret;
}
__weak_reference(_wait, wait);
pid_t
_wait(int *istat)
{
pid_t ret;
_thread_enter_cancellation_point();
ret = __wait(istat);
_thread_leave_cancellation_point();
return ret;
}
__weak_reference(_wait4, wait4);
pid_t
_wait4(pid_t pid, int *istat, int options, struct rusage *rusage)
{
pid_t ret;
_thread_enter_cancellation_point();
ret = __sys_wait4(pid, istat, options, rusage);
_thread_leave_cancellation_point();
return ret;
}
__weak_reference(_waitpid, waitpid);
pid_t
_waitpid(pid_t wpid, int *status, int options)
{
pid_t ret;
_thread_enter_cancellation_point();
ret = __waitpid(wpid, status, options);
_thread_leave_cancellation_point();
return ret;
}
__weak_reference(_write, write);
ssize_t
_write(int fd, const void *buf, size_t nbytes)
{
ssize_t ret;
_thread_enter_cancellation_point();
ret = __sys_write(fd, buf, nbytes);
_thread_leave_cancellation_point();
return ret;
}
__weak_reference(_writev, writev);
ssize_t
_writev(int fd, const struct iovec *iov, int iovcnt)
{
ssize_t ret;
_thread_enter_cancellation_point();
ret = __sys_writev(fd, iov, iovcnt);
_thread_leave_cancellation_point();
return ret;
}