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Update.

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2000-05-07  H.J. Lu  <hjl@gnu.org>

	* csu/initfini.c: Moved to ....
	* sysdeps/generic/initfini.c: ...here.

	* csu/Makefile (initfini.c): Set vpath to $(full_config_sysdirs).
This commit is contained in:
Ulrich Drepper
2000-05-08 00:03:03 +00:00
parent 639c6286de
commit 93414bb97c
8 changed files with 74 additions and 8 deletions
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38
linuxthreads/mutex.c
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@@ -17,6 +17,7 @@
#include <errno.h>
#include <sched.h>
#include <stddef.h>
#include <limits.h>
#include "pthread.h"
#include "internals.h"
#include "spinlock.h"
@@ -170,6 +171,7 @@ weak_alias (__pthread_mutexattr_getkind_np, pthread_mutexattr_getkind_np)
static pthread_mutex_t once_masterlock = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t once_finished = PTHREAD_COND_INITIALIZER;
static int fork_generation = 0; /* Child process increments this after fork. */
enum { NEVER = 0, IN_PROGRESS = 1, DONE = 2 };
@@ -199,14 +201,20 @@ int __pthread_once(pthread_once_t * once_control, void (*init_routine)(void))
state_changed = 0;
pthread_mutex_lock(&once_masterlock);
/* If this object was left in an IN_PROGRESS state in a parent
process (indicated by stale generation field), reset it to NEVER. */
if ((*once_control & 3) == IN_PROGRESS && (*once_control & ~3) != fork_generation)
*once_control = NEVER;
/* If init_routine is being called from another routine, wait until
it completes. */
while (*once_control == IN_PROGRESS) {
while ((*once_control & 3) == IN_PROGRESS) {
pthread_cond_wait(&once_finished, &once_masterlock);
}
/* Here *once_control is stable and either NEVER or DONE. */
if (*once_control == NEVER) {
*once_control = IN_PROGRESS;
*once_control = IN_PROGRESS | fork_generation;
pthread_mutex_unlock(&once_masterlock);
pthread_cleanup_push(pthread_once_cancelhandler, once_control);
init_routine();
@@ -225,13 +233,31 @@ int __pthread_once(pthread_once_t * once_control, void (*init_routine)(void))
strong_alias (__pthread_once, pthread_once)
/*
* This is called in the child process after a fork to make
* sure that the global mutex pthread_once is not held,
* and that the condition variable is reset to an initial state.
* Handle the state of the pthread_once mechanism across forks. The
* once_masterlock is acquired in the parent process prior to a fork to ensure
* that no thread is in the critical region protected by the lock. After the
* fork, the lock is released. In the child, the lock and the condition
* variable are simply reset. The child also increments its generation
* counter which lets pthread_once calls detect stale IN_PROGRESS states
* and reset them back to NEVER.
*/
void __pthread_reset_pthread_once(void)
void __pthread_once_fork_prepare(void)
{
pthread_mutex_lock(&once_masterlock);
}
void __pthread_once_fork_parent(void)
{
pthread_mutex_unlock(&once_masterlock);
}
void __pthread_once_fork_child(void)
{
pthread_mutex_init(&once_masterlock, NULL);
pthread_cond_init(&once_finished, NULL);
if (fork_generation <= INT_MAX - 4)
fork_generation += 4; /* leave least significant two bits zero */
else
fork_generation = 0;
}