freebsd-dev/lib/libpthread/thread/thr_init.c
John Birrell 58a7cc5d1b [ The author's description... ]
o Runnable threads are now maintained in priority queues.  The
    implementation requires two things:

      1.) The priority queues must be protected during insertion
          and removal of threads.  Since the kernel scheduler
          must modify the priority queues, a spinlock for
          protection cannot be used.   The functions
          _thread_kern_sched_defer() and _thread_kern_sched_undefer()
          were added to {un}defer kernel scheduler activation.

      2.) A thread (active) priority change can be performed only
          when the thread is removed from the priority queue.  The
          implementation uses a threads active priority when
          inserting it into the queue.

    A by-product is that thread switches are much faster.  A
    separate queue is used for waiting and/or blocked threads,
    and it is searched at most 2 times in the kernel scheduler
    when there are active threads.  It should be possible to
    reduce this to once by combining polling of threads waiting
    on I/O with the loop that looks for timed out threads and
    the minimum timeout value.

  o Functions to defer kernel scheduler activation were added.  These
    are _thread_kern_sched_defer() and _thread_kern_sched_undefer()
    and may be called recursively.  These routines do not block the
    scheduling signal, but latch its occurrence.  The signal handler
    will not call the kernel scheduler when the running thread has
    deferred scheduling, but it will be called when running thread
    undefers scheduling.

  o Added support for _POSIX_THREAD_PRIORITY_SCHEDULING.  All the
    POSIX routines required by this should now be implemented.
    One note, SCHED_OTHER, SCHED_FIFO, and SCHED_RR are required
    to be defined by including pthread.h.  These defines are currently
    in sched.h.  I modified pthread.h to include sched.h but don't
    know if this is the proper thing to do.

  o Added support for priority protection and inheritence mutexes.
    This allows definition of _POSIX_THREAD_PRIO_PROTECT and
    _POSIX_THREAD_PRIO_INHERIT.

  o Added additional error checks required by POSIX for mutexes and
    condition variables.

  o Provided a wrapper for sigpending which is marked as a hidden
    syscall.

  o Added a non-portable function as a debugging aid to allow an
    application to monitor thread context switches.  An application
    can install a routine that gets called everytime a thread
    (explicitly created by the application) gets context switched.
    The routine gets passed the pthread IDs of the threads that are
    being switched in and out.

Submitted by: Dan Eischen <eischen@vigrid.com>

Changes by me:

  o Added a PS_SPINBLOCK state to deal with the priority inversion
    problem most often (I think) seen by threads calling malloc/free/realloc.

  o Dispatch signals to the running thread directly rather than at a
    context switch to avoid the situation where the switch never occurs.
1999-03-23 05:07:56 +00:00

313 lines
9.8 KiB
C

/*
* 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.
*
*/
/* Allocate space for global thread variables here: */
#define GLOBAL_PTHREAD_PRIVATE
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <paths.h>
#include <unistd.h>
#include <sys/time.h>
#include <sys/ttycom.h>
#ifdef _THREAD_SAFE
#include <machine/reg.h>
#include <pthread.h>
#include "pthread_private.h"
#ifdef GCC_2_8_MADE_THREAD_AWARE
typedef void *** (*dynamic_handler_allocator)();
extern void __set_dynamic_handler_allocator(dynamic_handler_allocator);
static pthread_key_t except_head_key;
typedef struct {
void **__dynamic_handler_chain;
void *top_elt[2];
} except_struct;
static void ***dynamic_allocator_handler_fn()
{
except_struct *dh = (except_struct *)pthread_getspecific(except_head_key);
if(dh == NULL) {
dh = (except_struct *)malloc( sizeof(except_struct) );
memset(dh, '\0', sizeof(except_struct));
dh->__dynamic_handler_chain= dh->top_elt;
pthread_setspecific(except_head_key, (void *)dh);
}
return &dh->__dynamic_handler_chain;
}
#endif /* GCC_2_8_MADE_THREAD_AWARE */
/*
* Threaded process initialization
*/
void
_thread_init(void)
{
int fd;
int flags;
int i;
struct sigaction act;
/* Check if this function has already been called: */
if (_thread_initial)
/* Only initialise the threaded application once. */
return;
/*
* Check for the special case of this process running as
* or in place of init as pid = 1:
*/
if (getpid() == 1) {
/*
* Setup a new session for this process which is
* assumed to be running as root.
*/
if (setsid() == -1)
PANIC("Can't set session ID");
if (revoke(_PATH_CONSOLE) != 0)
PANIC("Can't revoke console");
if ((fd = _thread_sys_open(_PATH_CONSOLE, O_RDWR)) < 0)
PANIC("Can't open console");
if (setlogin("root") == -1)
PANIC("Can't set login to root");
if (_thread_sys_ioctl(fd,TIOCSCTTY, (char *) NULL) == -1)
PANIC("Can't set controlling terminal");
if (_thread_sys_dup2(fd,0) == -1 ||
_thread_sys_dup2(fd,1) == -1 ||
_thread_sys_dup2(fd,2) == -1)
PANIC("Can't dup2");
}
/* Get the standard I/O flags before messing with them : */
for (i = 0; i < 3; i++)
if ((_pthread_stdio_flags[i] =
_thread_sys_fcntl(i,F_GETFL, NULL)) == -1)
PANIC("Cannot get stdio flags");
/*
* Create a pipe that is written to by the signal handler to prevent
* signals being missed in calls to _select:
*/
if (_thread_sys_pipe(_thread_kern_pipe) != 0) {
/* Cannot create pipe, so abort: */
PANIC("Cannot create kernel pipe");
}
/* Get the flags for the read pipe: */
else if ((flags = _thread_sys_fcntl(_thread_kern_pipe[0], F_GETFL, NULL)) == -1) {
/* Abort this application: */
PANIC("Cannot get kernel read pipe flags");
}
/* Make the read pipe non-blocking: */
else if (_thread_sys_fcntl(_thread_kern_pipe[0], F_SETFL, flags | O_NONBLOCK) == -1) {
/* Abort this application: */
PANIC("Cannot make kernel read pipe non-blocking");
}
/* Get the flags for the write pipe: */
else if ((flags = _thread_sys_fcntl(_thread_kern_pipe[1], F_GETFL, NULL)) == -1) {
/* Abort this application: */
PANIC("Cannot get kernel write pipe flags");
}
/* Make the write pipe non-blocking: */
else if (_thread_sys_fcntl(_thread_kern_pipe[1], F_SETFL, flags | O_NONBLOCK) == -1) {
/* Abort this application: */
PANIC("Cannot get kernel write pipe flags");
}
/* Initialize the ready queue: */
else if (_pq_init(&_readyq, PTHREAD_MIN_PRIORITY, PTHREAD_MAX_PRIORITY) != 0) {
/* Abort this application: */
PANIC("Cannot allocate priority ready queue.");
}
/* Allocate memory for the thread structure of the initial thread: */
else if ((_thread_initial = (pthread_t) malloc(sizeof(struct pthread))) == NULL) {
/*
* Insufficient memory to initialise this application, so
* abort:
*/
PANIC("Cannot allocate memory for initial thread");
} else {
/* Zero the global kernel thread structure: */
memset(&_thread_kern_thread, 0, sizeof(struct pthread));
_thread_kern_thread.flags = PTHREAD_FLAGS_PRIVATE;
memset(_thread_initial, 0, sizeof(struct pthread));
/* Initialize the waiting queue: */
TAILQ_INIT(&_waitingq);
/* Initialize the scheduling switch hook routine: */
_sched_switch_hook = NULL;
/*
* Write a magic value to the thread structure
* to help identify valid ones:
*/
_thread_initial->magic = PTHREAD_MAGIC;
/* Default the priority of the initial thread: */
_thread_initial->base_priority = PTHREAD_DEFAULT_PRIORITY;
_thread_initial->active_priority = PTHREAD_DEFAULT_PRIORITY;
_thread_initial->inherited_priority = 0;
/* Initialise the state of the initial thread: */
_thread_initial->state = PS_RUNNING;
/* Initialise the queue: */
_thread_queue_init(&(_thread_initial->join_queue));
/* Initialize the owned mutex queue and count: */
TAILQ_INIT(&(_thread_initial->mutexq));
_thread_initial->priority_mutex_count = 0;
/* Initialise the rest of the fields: */
_thread_initial->sched_defer_count = 0;
_thread_initial->yield_on_sched_undefer = 0;
_thread_initial->specific_data = NULL;
_thread_initial->cleanup = NULL;
_thread_initial->queue = NULL;
_thread_initial->qnxt = NULL;
_thread_initial->nxt = NULL;
_thread_initial->flags = 0;
_thread_initial->error = 0;
_thread_link_list = _thread_initial;
_thread_run = _thread_initial;
/* Initialise the global signal action structure: */
sigfillset(&act.sa_mask);
act.sa_handler = (void (*) ()) _thread_sig_handler;
act.sa_flags = 0;
/* Enter a loop to get the existing signal status: */
for (i = 1; i < NSIG; i++) {
/* Check for signals which cannot be trapped: */
if (i == SIGKILL || i == SIGSTOP) {
}
/* Get the signal handler details: */
else if (_thread_sys_sigaction(i, NULL,
&_thread_sigact[i - 1]) != 0) {
/*
* Abort this process if signal
* initialisation fails:
*/
PANIC("Cannot read signal handler info");
}
}
/*
* Install the signal handler for the most important
* signals that the user-thread kernel needs. Actually
* SIGINFO isn't really needed, but it is nice to have.
*/
if (_thread_sys_sigaction(_SCHED_SIGNAL, &act, NULL) != 0 ||
_thread_sys_sigaction(SIGINFO, &act, NULL) != 0 ||
_thread_sys_sigaction(SIGCHLD, &act, NULL) != 0) {
/*
* Abort this process if signal initialisation fails:
*/
PANIC("Cannot initialise signal handler");
}
/* Get the table size: */
if ((_thread_dtablesize = getdtablesize()) < 0) {
/*
* Cannot get the system defined table size, so abort
* this process.
*/
PANIC("Cannot get dtablesize");
}
/* Allocate memory for the file descriptor table: */
if ((_thread_fd_table = (struct fd_table_entry **) malloc(sizeof(struct fd_table_entry *) * _thread_dtablesize)) == NULL) {
/*
* Cannot allocate memory for the file descriptor
* table, so abort this process.
*/
PANIC("Cannot allocate memory for file descriptor table");
} else {
/*
* Enter a loop to initialise the file descriptor
* table:
*/
for (i = 0; i < _thread_dtablesize; i++) {
/* Initialise the file descriptor table: */
_thread_fd_table[i] = NULL;
}
}
}
#ifdef GCC_2_8_MADE_THREAD_AWARE
/* Create the thread-specific data for the exception linked list. */
if(pthread_key_create(&except_head_key, NULL) != 0)
PANIC("Failed to create thread specific execption head");
/* Setup the gcc exception handler per thread. */
__set_dynamic_handler_allocator( dynamic_allocator_handler_fn );
#endif /* GCC_2_8_MADE_THREAD_AWARE */
/* Initialise the garbage collector mutex and condition variable. */
if (pthread_mutex_init(&_gc_mutex,NULL) != 0 ||
pthread_cond_init(&_gc_cond,NULL) != 0)
PANIC("Failed to initialise garbage collector mutex or condvar");
gettimeofday(&kern_inc_prio_time, NULL);
return;
}
/*
* Special start up code for NetBSD/Alpha
*/
#if defined(__NetBSD__) && defined(__alpha__)
int
main(int argc, char *argv[], char *env);
int
_thread_main(int argc, char *argv[], char *env)
{
_thread_init();
return (main(argc, argv, env));
}
#endif
#else
/*
* A stub for non-threaded programs.
*/
void
_thread_init(void)
{
}
#endif