AuroraMiddleware/glibc
1
0
Fork 0
mirror of https://sourceware.org/git/glibc.git synced 2024-12-17 16:31:07 +00:00
Code Issues Packages Projects Releases Wiki Activity

Redesigned how cancellation unblocks a thread from internal cancellation points (sem_wait, pthread_join, pthread_cond_{wait,timedwait}). Cancellation won't eat a signal in any of these functions (*required* by POSIX and Single Unix Spec!).

Browse Source 
2000-01-03  Kaz Kylheku  <kaz@ashi.footprints.net>

	Redesigned how cancellation unblocks a thread from internal
	cancellation points (sem_wait, pthread_join,
	pthread_cond_{wait,timedwait}).
	Cancellation won't eat a signal in any of these functions
	(*required* by POSIX and Single Unix Spec!).
	* condvar.c: spontaneous wakeup on pthread_cond_timedwait won't eat a
	simultaneous condition variable signal (not required by POSIX
	or Single Unix Spec, but nice).
	* spinlock.c: __pthread_lock queues back any received restarts
	that don't belong to it instead of assuming ownership of lock
	upon any restart; fastlock can no longer be acquired by two threads
	simultaneously.
	* restart.h: restarts queue even on kernels that don't have
	queued real time signals (2.0, early 2.1), thanks to atomic counter,
	avoiding a rare race condition in pthread_cond_timedwait.
This commit is contained in:
Ulrich Drepper 2000-01-05 02:09:12 +00:00
parent f19f2b3443
commit 1d2fc9b3c5
14 changed files with 719 additions and 107 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
linuxthreads/ChangeLog
View File

@ -1,3 +1,21 @@
2000-01-03 Kaz Kylheku <kaz@ashi.footprints.net>
Redesigned how cancellation unblocks a thread from internal
cancellation points (sem_wait, pthread_join,
pthread_cond_{wait,timedwait}).
Cancellation won't eat a signal in any of these functions
(*required* by POSIX and Single Unix Spec!).
* condvar.c: spontaneous wakeup on pthread_cond_timedwait won't eat a
simultaneous condition variable signal (not required by POSIX
or Single Unix Spec, but nice).
* spinlock.c: __pthread_lock queues back any received restarts
that don't belong to it instead of assuming ownership of lock
upon any restart; fastlock can no longer be acquired by two threads
simultaneously.
* restart.h: restarts queue even on kernels that don't have
queued real time signals (2.0, early 2.1), thanks to atomic counter,
avoiding a rare race condition in pthread_cond_timedwait.
1999-12-31 Andreas Jaeger <aj@suse.de>
* internals.h: Remove duplicate prototype declarations.

44
linuxthreads/cancel.c
View File

@ -52,16 +52,54 @@ int pthread_cancel(pthread_t thread)
{
pthread_handle handle = thread_handle(thread);
int pid;
int dorestart = 0;
pthread_descr th;
pthread_extricate_if *pextricate;
__pthread_lock(&handle->h_lock, NULL);
if (invalid_handle(handle, thread)) {
__pthread_unlock(&handle->h_lock);
return ESRCH;
}
handle->h_descr->p_canceled = 1;
pid = handle->h_descr->p_pid;
th = handle->h_descr;
if (th->p_canceled) {
__pthread_unlock(&handle->h_lock);
return 0;
}
pextricate = th->p_extricate;
th->p_canceled = 1;
pid = th->p_pid;
/* If the thread has registered an extrication interface, then
invoke the interface. If it returns 1, then we succeeded in
dequeuing the thread from whatever waiting object it was enqueued
with. In that case, it is our responsibility to wake it up.
And also to set the p_woken_by_cancel flag so the woken thread
can tell that it was woken by cancellation. */
if (pextricate != NULL) {
dorestart = pextricate->pu_extricate_func(pextricate->pu_object, th);
th->p_woken_by_cancel = dorestart;
}
__pthread_unlock(&handle->h_lock);
kill(pid, __pthread_sig_cancel);
/* If the thread has suspended or is about to, then we unblock it by
issuing a restart, instead of a cancel signal. Otherwise we send
the cancel signal to unblock the thread from a cancellation point,
or to initiate asynchronous cancellation. The restart is needed so
we have proper accounting of restarts; suspend decrements the thread's
resume count, and restart() increments it. This also means that suspend's
handling of the cancel signal is obsolete. */
if (dorestart)
restart(th);
else
kill(pid, __pthread_sig_cancel);
return 0;
}

334
linuxthreads/condvar.c
View File

@ -25,6 +25,22 @@
#include "queue.h"
#include "restart.h"
static int pthread_cond_timedwait_relative_old(pthread_cond_t *,
pthread_mutex_t *, const struct timespec *);
static int pthread_cond_timedwait_relative_new(pthread_cond_t *,
pthread_mutex_t *, const struct timespec *);
static int (*pthread_cond_tw_rel)(pthread_cond_t *, pthread_mutex_t *,
const struct timespec *) = pthread_cond_timedwait_relative_old;
/* initialize this module */
void __pthread_init_condvar(int rt_sig_available)
{
if (rt_sig_available)
pthread_cond_tw_rel = pthread_cond_timedwait_relative_new;
}
int pthread_cond_init(pthread_cond_t *cond,
const pthread_condattr_t *cond_attr)
{
@ -39,54 +55,125 @@ int pthread_cond_destroy(pthread_cond_t *cond)
return 0;
}
/* Function called by pthread_cancel to remove the thread from
waiting on a condition variable queue. */
static int cond_extricate_func(void *obj, pthread_descr th)
{
volatile pthread_descr self = thread_self();
pthread_cond_t *cond = obj;
int did_remove = 0;
__pthread_lock(&cond->__c_lock, self);
did_remove = remove_from_queue(&cond->__c_waiting, th);
__pthread_unlock(&cond->__c_lock);
return did_remove;
}
int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
{
volatile pthread_descr self = thread_self();
pthread_extricate_if extr;
int already_canceled = 0;
/* Set up extrication interface */
extr.pu_object = cond;
extr.pu_extricate_func = cond_extricate_func;
/* Register extrication interface */
__pthread_set_own_extricate_if(self, &extr);
/* Atomically enqueue thread for waiting, but only if it is not
canceled. If the thread is canceled, then it will fall through the
suspend call below, and then call pthread_exit without
having to worry about whether it is still on the condition variable queue.
This depends on pthread_cancel setting p_canceled before calling the
extricate function. */
__pthread_lock(&cond->__c_lock, self);
enqueue(&cond->__c_waiting, self);
if (!(THREAD_GETMEM(self, p_canceled)
&& THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE))
enqueue(&cond->__c_waiting, self);
else
already_canceled = 1;
__pthread_unlock(&cond->__c_lock);
pthread_mutex_unlock(mutex);
suspend_with_cancellation(self);
pthread_mutex_lock(mutex);
/* This is a cancellation point */
if (THREAD_GETMEM(self, p_canceled)
&& THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE) {
/* Remove ourselves from the waiting queue if we're still on it */
__pthread_lock(&cond->__c_lock, self);
remove_from_queue(&cond->__c_waiting, self);
__pthread_unlock(&cond->__c_lock);
if (already_canceled) {
__pthread_set_own_extricate_if(self, 0);
pthread_exit(PTHREAD_CANCELED);
}
pthread_mutex_unlock(mutex);
suspend(self);
__pthread_set_own_extricate_if(self, 0);
/* Check for cancellation again, to provide correct cancellation
point behavior */
if (THREAD_GETMEM(self, p_woken_by_cancel)
&& THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE) {
THREAD_SETMEM(self, p_woken_by_cancel, 0);
pthread_mutex_lock(mutex);
pthread_exit(PTHREAD_CANCELED);
}
pthread_mutex_lock(mutex);
return 0;
}
/* The following function is used on kernels that don't have rt signals.
SIGUSR1 is used as the restart signal. The different code is needed
because that ordinary signal does not queue. */
static int
pthread_cond_timedwait_relative(pthread_cond_t *cond,
pthread_cond_timedwait_relative_old(pthread_cond_t *cond,
pthread_mutex_t *mutex,
const struct timespec * reltime)
{
volatile pthread_descr self = thread_self();
sigset_t unblock, initial_mask;
int retsleep;
int retsleep, already_canceled, was_signalled;
sigjmp_buf jmpbuf;
pthread_extricate_if extr;
/* Wait on the condition */
requeue_and_wait_again:
retsleep = 0;
already_canceled = 0;
was_signalled = 0;
/* Set up extrication interface */
extr.pu_object = cond;
extr.pu_extricate_func = cond_extricate_func;
/* Register extrication interface */
__pthread_set_own_extricate_if(self, &extr);
/* Enqueue to wait on the condition and check for cancellation. */
__pthread_lock(&cond->__c_lock, self);
enqueue(&cond->__c_waiting, self);
if (!(THREAD_GETMEM(self, p_canceled)
&& THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE))
enqueue(&cond->__c_waiting, self);
else
already_canceled = 1;
__pthread_unlock(&cond->__c_lock);
if (already_canceled) {
__pthread_set_own_extricate_if(self, 0);
pthread_exit(PTHREAD_CANCELED);
}
pthread_mutex_unlock(mutex);
continue_waiting:
/* Set up a longjmp handler for the restart and cancel signals */
if (sigsetjmp(jmpbuf, 1) == 0) {
THREAD_SETMEM(self, p_signal_jmp, &jmpbuf);
THREAD_SETMEM(self, p_cancel_jmp, &jmpbuf);
THREAD_SETMEM(self, p_signal, 0);
/* Check for cancellation */
if (THREAD_GETMEM(self, p_canceled)
&& THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE) {
retsleep = -1;
} else {
if (atomic_decrement(&self->p_resume_count) == 0) {
/* Set up a longjmp handler for the restart signal, unblock
the signal and sleep. */
if (sigsetjmp(jmpbuf, 1) == 0) {
THREAD_SETMEM(self, p_signal_jmp, &jmpbuf);
THREAD_SETMEM(self, p_signal, 0);
/* Unblock the restart signal */
sigemptyset(&unblock);
sigaddset(&unblock, __pthread_sig_restart);
@ -95,37 +182,180 @@ pthread_cond_timedwait_relative(pthread_cond_t *cond,
retsleep = __libc_nanosleep(reltime, NULL);
/* Block the restart signal again */
sigprocmask(SIG_SETMASK, &initial_mask, NULL);
was_signalled = 0;
} else {
retsleep = -1;
was_signalled = 1;
}
} else {
retsleep = -1;
THREAD_SETMEM(self, p_signal_jmp, NULL);
}
THREAD_SETMEM(self, p_signal_jmp, NULL);
THREAD_SETMEM(self, p_cancel_jmp, NULL);
/* Here, either the condition was signaled (self->p_signal != 0)
or we got canceled (self->p_canceled != 0)
or the timeout occurred (retsleep == 0)
or another interrupt occurred (retsleep == -1) */
/* This is a cancellation point */
if (THREAD_GETMEM(self, p_canceled)
/* Now was_signalled is true if we exited the above code
due to the delivery of a restart signal. In that case,
we know we have been dequeued and resumed and that the
resume count is balanced. Otherwise, there are some
cases to consider. First, try to bump up the resume count
back to zero. If it goes to 1, it means restart() was
invoked on this thread. The signal must be consumed
and the count bumped down and everything is cool.
Otherwise, no restart was delivered yet, so we remove
the thread from the queue. If this succeeds, it's a clear
case of timeout. If we fail to remove from the queue, then we
must wait for a restart. */
if (!was_signalled) {
if (atomic_increment(&self->p_resume_count) != -1) {
__pthread_wait_for_restart_signal(self);
atomic_decrement(&self->p_resume_count); /* should be zero now! */
} else {
int was_on_queue;
__pthread_lock(&cond->__c_lock, self);
was_on_queue = remove_from_queue(&cond->__c_waiting, self);
__pthread_unlock(&cond->__c_lock);
if (was_on_queue) {
__pthread_set_own_extricate_if(self, 0);
pthread_mutex_lock(mutex);
if (retsleep == 0)
return ETIMEDOUT;
/* Woken by a signal: resume waiting as
required by Single Unix Specification. */
goto requeue_and_wait_again;
}
suspend(self);
}
}
__pthread_set_own_extricate_if(self, 0);
/* The remaining logic is the same as in other cancellable waits,
such as pthread_join sem_wait or pthread_cond wait. */
if (THREAD_GETMEM(self, p_woken_by_cancel)
&& THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE) {
__pthread_lock(&cond->__c_lock, self);
remove_from_queue(&cond->__c_waiting, self);
__pthread_unlock(&cond->__c_lock);
THREAD_SETMEM(self, p_woken_by_cancel, 0);
pthread_mutex_lock(mutex);
pthread_exit(PTHREAD_CANCELED);
}
/* If not signaled: also remove ourselves and return an error code, but
only if the timeout has elapsed. If not, just continue waiting. */
if (THREAD_GETMEM(self, p_signal) == 0) {
if (retsleep != 0)
goto continue_waiting;
__pthread_lock(&cond->__c_lock, self);
remove_from_queue(&cond->__c_waiting, self);
__pthread_unlock(&cond->__c_lock);
pthread_mutex_lock(mutex);
return ETIMEDOUT;
pthread_mutex_lock(mutex);
return 0;
}
/* The following function is used on new (late 2.1 and 2.2 and higher) kernels
that have rt signals which queue. */
static int
pthread_cond_timedwait_relative_new(pthread_cond_t *cond,
pthread_mutex_t *mutex,
const struct timespec * reltime)
{
volatile pthread_descr self = thread_self();
sigset_t unblock, initial_mask;
int retsleep, already_canceled, was_signalled;
sigjmp_buf jmpbuf;
pthread_extricate_if extr;
requeue_and_wait_again:
retsleep = 0;
already_canceled = 0;
was_signalled = 0;
/* Set up extrication interface */
extr.pu_object = cond;
extr.pu_extricate_func = cond_extricate_func;
/* Register extrication interface */
__pthread_set_own_extricate_if(self, &extr);
/* Enqueue to wait on the condition and check for cancellation. */
__pthread_lock(&cond->__c_lock, self);
if (!(THREAD_GETMEM(self, p_canceled)
&& THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE))
enqueue(&cond->__c_waiting, self);
else
already_canceled = 1;
__pthread_unlock(&cond->__c_lock);
if (already_canceled) {
__pthread_set_own_extricate_if(self, 0);
pthread_exit(PTHREAD_CANCELED);
}
/* Otherwise, return normally */
pthread_mutex_unlock(mutex);
/* Set up a longjmp handler for the restart signal, unblock
the signal and sleep. */
if (sigsetjmp(jmpbuf, 1) == 0) {
THREAD_SETMEM(self, p_signal_jmp, &jmpbuf);
THREAD_SETMEM(self, p_signal, 0);
/* Unblock the restart signal */
sigemptyset(&unblock);
sigaddset(&unblock, __pthread_sig_restart);
sigprocmask(SIG_UNBLOCK, &unblock, &initial_mask);
/* Sleep for the required duration */
retsleep = __libc_nanosleep(reltime, NULL);
/* Block the restart signal again */
sigprocmask(SIG_SETMASK, &initial_mask, NULL);
was_signalled = 0;
} else {
retsleep = -1;
was_signalled = 1;
}
THREAD_SETMEM(self, p_signal_jmp, NULL);
/* Now was_signalled is true if we exited the above code
due to the delivery of a restart signal. In that case,
everything is cool. We have been removed from the queue
by the other thread, and consumed its signal.
Otherwise we this thread woke up spontaneously, or due to a signal other
than restart. The next thing to do is to try to remove the thread
from the queue. This may fail due to a race against another thread
trying to do the same. In the failed case, we know we were signalled,
and we may also have to consume a restart signal. */
if (!was_signalled) {
int was_on_queue;
/* __pthread_lock will queue back any spurious restarts that
may happen to it. */
__pthread_lock(&cond->__c_lock, self);
was_on_queue = remove_from_queue(&cond->__c_waiting, self);
__pthread_unlock(&cond->__c_lock);
if (was_on_queue) {
__pthread_set_own_extricate_if(self, 0);
pthread_mutex_lock(mutex);
if (retsleep == 0)
return ETIMEDOUT;
/* Woken by a signal: resume waiting as
required by Single Unix Specification. */
goto requeue_and_wait_again;
}
/* Eat the outstanding restart() from the signaller */
suspend(self);
}
__pthread_set_own_extricate_if(self, 0);
/* The remaining logic is the same as in other cancellable waits,
such as pthread_join sem_wait or pthread_cond wait. */
if (THREAD_GETMEM(self, p_woken_by_cancel)
&& THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE) {
THREAD_SETMEM(self, p_woken_by_cancel, 0);
pthread_mutex_lock(mutex);
pthread_exit(PTHREAD_CANCELED);
}
pthread_mutex_lock(mutex);
return 0;
}
@ -144,7 +374,9 @@ int pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
reltime.tv_sec -= 1;
}
if (reltime.tv_sec < 0) return ETIMEDOUT;
return pthread_cond_timedwait_relative(cond, mutex, &reltime);
/* Indirect call through pointer! */
return pthread_cond_tw_rel(cond, mutex, &reltime);
}
int pthread_cond_signal(pthread_cond_t *cond)

40
linuxthreads/internals.h
View File

@ -86,6 +86,27 @@ struct pthread_key_struct {
typedef struct _pthread_descr_struct * pthread_descr;
/* Callback interface for removing the thread from waiting on an
object if it is cancelled while waiting or about to wait.
This hold a pointer to the object, and a pointer to a function
which ``extricates'' the thread from its enqueued state.
The function takes two arguments: pointer to the wait object,
and a pointer to the thread. It returns 1 if an extrication
actually occured, and hence the thread must also be signalled.
It returns 0 if the thread had already been extricated. */
typedef struct _pthread_extricate_struct {
void *pu_object;
int (*pu_extricate_func)(void *, pthread_descr);
} pthread_extricate_if;
/* Atomic counter made possible by compare_and_swap */
struct pthread_atomic {
long p_count;
int p_spinlock;
};
struct _pthread_descr_struct {
pthread_descr p_nextlive, p_prevlive;
/* Double chaining of active threads */
@ -96,6 +117,7 @@ struct _pthread_descr_struct {
int p_priority; /* Thread priority (== 0 if not realtime) */
struct _pthread_fastlock * p_lock; /* Spinlock for synchronized accesses */
int p_signal; /* last signal received */
struct pthread_atomic p_resume_count; /* number of times restart() was called on thread */
sigjmp_buf * p_signal_jmp; /* where to siglongjmp on a signal or NULL */
sigjmp_buf * p_cancel_jmp; /* where to siglongjmp on a cancel or NULL */
char p_terminated; /* true if terminated e.g. by pthread_exit */
@ -108,6 +130,8 @@ struct _pthread_descr_struct {
char p_cancelstate; /* cancellation state */
char p_canceltype; /* cancellation type (deferred/async) */
char p_canceled; /* cancellation request pending */
char p_woken_by_cancel; /* cancellation performed wakeup */
pthread_extricate_if *p_extricate; /* See above */
int * p_errnop; /* pointer to used errno variable */
int p_errno; /* error returned by last system call */
int * p_h_errnop; /* pointer to used h_errno variable */
@ -353,6 +377,7 @@ void __pthread_manager_sighandler(int sig);
void __pthread_reset_main_thread(void);
void __fresetlockfiles(void);
void __pthread_manager_adjust_prio(int thread_prio);
void __pthread_set_own_extricate_if(pthread_descr self, pthread_extricate_if *peif);
extern int __pthread_attr_setguardsize (pthread_attr_t *__attr,
size_t __guardsize);
@ -372,6 +397,21 @@ extern int __pthread_mutexattr_gettype (const pthread_mutexattr_t *__attr,
int *__kind);
extern void __pthread_kill_other_threads_np (void);
void __pthread_restart_old(pthread_descr th);
void __pthread_suspend_old(pthread_descr self);
void __pthread_restart_new(pthread_descr th);
void __pthread_suspend_new(pthread_descr self);
void __pthread_wait_for_restart_signal(pthread_descr self);
void __pthread_init_condvar(int rt_sig_available);
/* Global pointers to old or new suspend functions */
extern void (*__pthread_restart)(pthread_descr);
extern void (*__pthread_suspend)(pthread_descr);
/* Prototypes for the function without cancelation support when the
normal version has it. */
extern int __libc_close (int fd);

48
linuxthreads/join.c
View File

@ -79,12 +79,37 @@ void pthread_exit(void * retval)
_exit(0);
}
/* Function called by pthread_cancel to remove the thread from
waiting on a condition variable queue. */
static int join_extricate_func(void *obj, pthread_descr th)
{
volatile pthread_descr self = thread_self();
pthread_handle handle = obj;
pthread_descr jo;
int did_remove = 0;
__pthread_lock(&handle->h_lock, self);
jo = handle->h_descr;
did_remove = jo->p_joining != NULL;
jo->p_joining = NULL;
__pthread_unlock(&handle->h_lock);
return did_remove;
}
int pthread_join(pthread_t thread_id, void ** thread_return)
{
volatile pthread_descr self = thread_self();
struct pthread_request request;
pthread_handle handle = thread_handle(thread_id);
pthread_descr th;
pthread_extricate_if extr;
int already_canceled = 0;
/* Set up extrication interface */
extr.pu_object = handle;
extr.pu_extricate_func = join_extricate_func;
__pthread_lock(&handle->h_lock, self);
if (invalid_handle(handle, thread_id)) {
@ -103,13 +128,28 @@ int pthread_join(pthread_t thread_id, void ** thread_return)
}
/* If not terminated yet, suspend ourselves. */
if (! th->p_terminated) {
th->p_joining = self;
/* Register extrication interface */
__pthread_set_own_extricate_if(self, &extr);
if (!(THREAD_GETMEM(self, p_canceled)
&& THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE))
th->p_joining = self;
else
already_canceled = 1;
__pthread_unlock(&handle->h_lock);
suspend_with_cancellation(self);
if (already_canceled) {
__pthread_set_own_extricate_if(self, 0);
pthread_exit(PTHREAD_CANCELED);
}
suspend(self);
/* Deregister extrication interface */
__pthread_set_own_extricate_if(self, 0);
/* This is a cancellation point */
if (THREAD_GETMEM(self, p_canceled)
if (THREAD_GETMEM(self, p_woken_by_cancel)
&& THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE) {
th->p_joining = NULL;
THREAD_SETMEM(self, p_woken_by_cancel, 0);
pthread_exit(PTHREAD_CANCELED);
}
__pthread_lock(&handle->h_lock, self);

24
linuxthreads/oldsemaphore.c
View File

@ -68,13 +68,29 @@ int __old_sem_init(old_sem_t *sem, int pshared, unsigned int value)
return 0;
}
/* Function called by pthread_cancel to remove the thread from
waiting inside __old_sem_wait. Here we simply unconditionally
indicate that the thread is to be woken, by returning 1. */
static int old_sem_extricate_func(void *obj, pthread_descr th)
{
return 1;
}
int __old_sem_wait(old_sem_t * sem)
{
long oldstatus, newstatus;
volatile pthread_descr self = thread_self();
pthread_descr * th;
pthread_extricate_if extr;
/* Set up extrication interface */
extr.pu_object = 0;
extr.pu_extricate_func = old_sem_extricate_func;
while (1) {
/* Register extrication interface */
__pthread_set_own_extricate_if(self, &extr);
do {
oldstatus = sem->sem_status;
if ((oldstatus & 1) && (oldstatus != 1))
@ -85,11 +101,15 @@ int __old_sem_wait(old_sem_t * sem)
}
}
while (! sem_compare_and_swap(sem, oldstatus, newstatus));
if (newstatus & 1)
if (newstatus & 1) {
/* We got the semaphore. */
__pthread_set_own_extricate_if(self, 0);
return 0;
}
/* Wait for sem_post or cancellation */
suspend_with_cancellation(self);
suspend(self);
__pthread_set_own_extricate_if(self, 0);
/* This is a cancellation point */
if (self->p_canceled && self->p_cancelstate == PTHREAD_CANCEL_ENABLE) {
/* Remove ourselves from the waiting list if we're still on it */

66
linuxthreads/pthread.c
View File

@ -43,6 +43,7 @@ struct _pthread_descr_struct __pthread_initial_thread = {
0, /* int p_priority */
&__pthread_handles[0].h_lock, /* struct _pthread_fastlock * p_lock */
0, /* int p_signal */
ATOMIC_INITIALIZER, /* struct pthread_atomic p_resume_count */
NULL, /* sigjmp_buf * p_signal_buf */
NULL, /* sigjmp_buf * p_cancel_buf */
0, /* char p_terminated */
@ -55,6 +56,8 @@ struct _pthread_descr_struct __pthread_initial_thread = {
0, /* char p_cancelstate */
0, /* char p_canceltype */
0, /* char p_canceled */
0, /* char p_woken_by_cancel */
NULL, /* struct pthread_extricate_if *p_extricate */
NULL, /* int *p_errnop */
0, /* int p_errno */
NULL, /* int *p_h_errnop */
@ -86,6 +89,7 @@ struct _pthread_descr_struct __pthread_manager_thread = {
0, /* int p_priority */
&__pthread_handles[1].h_lock, /* struct _pthread_fastlock * p_lock */
0, /* int p_signal */
ATOMIC_INITIALIZER, /* struct pthread_atomic p_resume_count */
NULL, /* sigjmp_buf * p_signal_buf */
NULL, /* sigjmp_buf * p_cancel_buf */
0, /* char p_terminated */
@ -98,6 +102,8 @@ struct _pthread_descr_struct __pthread_manager_thread = {
0, /* char p_cancelstate */
0, /* char p_canceltype */
0, /* char p_canceled */
0, /* char p_woken_by_cancel */
NULL, /* struct pthread_extricate_if *p_extricate */
&__pthread_manager_thread.p_errno, /* int *p_errnop */
0, /* int p_errno */
NULL, /* int *p_h_errnop */
@ -144,6 +150,12 @@ char *__pthread_manager_thread_tos = NULL;
int __pthread_exit_requested = 0;
int __pthread_exit_code = 0;
/* Pointers that select new or old suspend/resume functions
based on availability of rt signals. */
void (*__pthread_restart)(pthread_descr) = __pthread_restart_old;
void (*__pthread_suspend)(pthread_descr) = __pthread_suspend_old;
/* Communicate relevant LinuxThreads constants to gdb */
const int __pthread_threads_max = PTHREAD_THREADS_MAX;
@ -215,13 +227,18 @@ init_rtsigs (void)
__pthread_sig_cancel = SIGUSR2;
__pthread_sig_debug = 0;
#endif
__pthread_init_condvar(0);
}
else
{
#if __SIGRTMAX - __SIGRTMIN >= 3
current_rtmin = __SIGRTMIN + 3;
__pthread_restart = __pthread_restart_new;
__pthread_suspend = __pthread_wait_for_restart_signal;
__pthread_init_condvar(1);
#else
current_rtmin = __SIGRTMIN;
__pthread_init_condvar(0);
#endif
current_rtmax = __SIGRTMAX;
@ -447,7 +464,7 @@ int __pthread_initialize_manager(void)
raise(__pthread_sig_debug);
/* We suspend ourself and gdb will wake us up when it is
ready to handle us. */
suspend(thread_self());
__pthread_wait_for_restart_signal(thread_self());
}
/* Synchronize debugging of the thread manager */
request.req_kind = REQ_DEBUG;
@ -770,6 +787,53 @@ int __pthread_getconcurrency(void)
}
weak_alias (__pthread_getconcurrency, pthread_getconcurrency)
void __pthread_set_own_extricate_if(pthread_descr self, pthread_extricate_if *peif)
{
__pthread_lock(self->p_lock, self);
THREAD_SETMEM(self, p_extricate, peif);
__pthread_unlock(self->p_lock);
}
/* Primitives for controlling thread execution */
void __pthread_wait_for_restart_signal(pthread_descr self)
{
sigset_t mask;
sigprocmask(SIG_SETMASK, NULL, &mask); /* Get current signal mask */
sigdelset(&mask, __pthread_sig_restart); /* Unblock the restart signal */
do {
self->p_signal = 0;
sigsuspend(&mask); /* Wait for signal */
} while (self->p_signal !=__pthread_sig_restart );
}
/* The _old variants are for 2.0 and early 2.1 kernels which don't have RT signals.
On these kernels, we use SIGUSR1 and SIGUSR2 for restart and cancellation.
Since the restart signal does not queue, we use an atomic counter to create
queuing semantics. This is needed to resolve a rare race condition in
pthread_cond_timedwait_relative. */
void __pthread_restart_old(pthread_descr th)
{
if (atomic_increment(&th->p_resume_count) == -1)
kill(th->p_pid, __pthread_sig_restart);
}
void __pthread_suspend_old(pthread_descr self)
{
if (atomic_decrement(&self->p_resume_count) <= 0)
__pthread_wait_for_restart_signal(self);
}
void __pthread_restart_new(pthread_descr th)
{
kill(th->p_pid, __pthread_sig_restart);
}
/* There is no __pthread_suspend_new because it would just
be a wasteful wrapper for __pthread_wait_for_restart_signal */
/* Debugging aid */
#ifdef DEBUG

5
linuxthreads/queue.h
View File

@ -43,13 +43,14 @@ static inline pthread_descr dequeue(pthread_descr * q)
return th;
}
static inline void remove_from_queue(pthread_descr * q, pthread_descr th)
static inline int remove_from_queue(pthread_descr * q, pthread_descr th)
{
for (; *q != NULL; q = &((*q)->p_nextwaiting)) {
if (*q == th) {
*q = th->p_nextwaiting;
th->p_nextwaiting = NULL;
return;
return 1;
}
}
return 0;
}

35
linuxthreads/restart.h
View File

@ -18,41 +18,10 @@
static inline void restart(pthread_descr th)
{
kill(th->p_pid, __pthread_sig_restart);
__pthread_restart(th); /* see pthread.c */
}
static inline void suspend(pthread_descr self)
{
sigset_t mask;
sigprocmask(SIG_SETMASK, NULL, &mask); /* Get current signal mask */
sigdelset(&mask, __pthread_sig_restart); /* Unblock the restart signal */
do {
self->p_signal = 0;
sigsuspend(&mask); /* Wait for signal */
} while (self->p_signal !=__pthread_sig_restart );
}
#define suspend_with_cancellation(self) \
{ \
sigset_t mask; \
sigjmp_buf jmpbuf; \
\
sigprocmask(SIG_SETMASK, NULL, &mask); /* Get current signal mask */ \
sigdelset(&mask, __pthread_sig_restart); /* Unblock the restart signal */ \
/* No need to save the signal mask, we'll restore it ourselves */ \
if (sigsetjmp(jmpbuf, 0) == 0) { \
self->p_cancel_jmp = &jmpbuf; \
if (! (self->p_canceled \
&& self->p_cancelstate == PTHREAD_CANCEL_ENABLE)) { \
do { \
self->p_signal = 0; \
sigsuspend(&mask); /* Wait for a signal */ \
} while (self->p_signal != __pthread_sig_restart); \
} \
self->p_cancel_jmp = NULL; \
} else { \
sigaddset(&mask, __pthread_sig_restart); /* Reblock the restart signal */ \
sigprocmask(SIG_SETMASK, &mask, NULL); \
} \
__pthread_suspend(self); /* see pthread.c */
}

2
linuxthreads/rwlock.c
View File

@ -23,8 +23,8 @@
#include <pthread.h>
#include "internals.h"
#include "queue.h"
#include "restart.h"
#include "spinlock.h"
#include "restart.h"
int
pthread_rwlock_init (pthread_rwlock_t *rwlock,

54
linuxthreads/semaphore.c
View File

@ -38,9 +38,31 @@ int __new_sem_init(sem_t *sem, int pshared, unsigned int value)
return 0;
}
/* Function called by pthread_cancel to remove the thread from
waiting inside __new_sem_wait. */
static int new_sem_extricate_func(void *obj, pthread_descr th)
{
volatile pthread_descr self = thread_self();
sem_t *sem = obj;
int did_remove = 0;
__pthread_lock((struct _pthread_fastlock *) &sem->__sem_lock, self);
did_remove = remove_from_queue(&sem->__sem_waiting, th);
__pthread_unlock((struct _pthread_fastlock *) &sem->__sem_lock);
return did_remove;
}
int __new_sem_wait(sem_t * sem)
{
volatile pthread_descr self = thread_self();
pthread_extricate_if extr;
int already_canceled = 0;
/* Set up extrication interface */
extr.pu_object = sem;
extr.pu_extricate_func = new_sem_extricate_func;
__pthread_lock((struct _pthread_fastlock *) &sem->__sem_lock, self);
if (sem->__sem_value > 0) {
@ -48,17 +70,31 @@ int __new_sem_wait(sem_t * sem)
__pthread_unlock((struct _pthread_fastlock *) &sem->__sem_lock);
return 0;
}
enqueue(&sem->__sem_waiting, self);
/* Wait for sem_post or cancellation */
/* Register extrication interface */
__pthread_set_own_extricate_if(self, &extr);
/* Enqueue only if not already cancelled. */
if (!(THREAD_GETMEM(self, p_canceled)
&& THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE))
enqueue(&sem->__sem_waiting, self);
else
already_canceled = 1;
__pthread_unlock((struct _pthread_fastlock *) &sem->__sem_lock);
suspend_with_cancellation(self);
/* This is a cancellation point */
if (THREAD_GETMEM(self, p_canceled)
if (already_canceled) {
__pthread_set_own_extricate_if(self, 0);
pthread_exit(PTHREAD_CANCELED);
}
/* Wait for sem_post or cancellation, or fall through if already canceled */
suspend(self);
__pthread_set_own_extricate_if(self, 0);
/* Terminate only if the wakeup came from cancellation. */
/* Otherwise ignore cancellation because we got the semaphore. */
if (THREAD_GETMEM(self, p_woken_by_cancel)
&& THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE) {
/* Remove ourselves from the waiting list if we're still on it */
__pthread_lock((struct _pthread_fastlock *) &sem->__sem_lock, self);
remove_from_queue(&sem->__sem_waiting, self);
__pthread_unlock((struct _pthread_fastlock *) &sem->__sem_lock);
THREAD_SETMEM(self, p_woken_by_cancel, 0);
pthread_exit(PTHREAD_CANCELED);
}
/* We got the semaphore */

24
linuxthreads/spinlock.c
View File

@ -40,6 +40,7 @@ void internal_function __pthread_lock(struct _pthread_fastlock * lock,
pthread_descr self)
{
long oldstatus, newstatus;
int spurious_wakeup_count = 0;
do {
oldstatus = lock->__status;
@ -56,7 +57,28 @@ void internal_function __pthread_lock(struct _pthread_fastlock * lock,
}
} while(! compare_and_swap(&lock->__status, oldstatus, newstatus,
&lock->__spinlock));
if (oldstatus != 0) suspend(self);
/* Suspend with guard against spurious wakeup.
This can happen in pthread_cond_timedwait_relative, when the thread
wakes up due to timeout and is still on the condvar queue, and then
locks the queue to remove itself. At that point it may still be on the
queue, and may be resumed by a condition signal. */
if (oldstatus != 0) {
for (;;) {
suspend(self);
if (self->p_nextlock != NULL) {
/* Count resumes that don't belong to us. */
spurious_wakeup_count++;
continue;
}
break;
}
}
/* Put back any resumes we caught that don't belong to us. */
while (spurious_wakeup_count--)
restart(self);
}
void internal_function __pthread_unlock(struct _pthread_fastlock * lock)

28
linuxthreads/spinlock.h
View File

@ -72,3 +72,31 @@ static inline int __pthread_trylock (struct _pthread_fastlock * lock)
}
#define LOCK_INITIALIZER {0, 0}
/* Operations on pthread_atomic, which is defined in internals.h */
static inline long atomic_increment(struct pthread_atomic *pa)
{
long oldval;
do {
oldval = pa->p_count;
} while (!compare_and_swap(&pa->p_count, oldval, oldval + 1, &pa->p_spinlock));
return oldval;
}
static inline long atomic_decrement(struct pthread_atomic *pa)
{
long oldval;
do {
oldval = pa->p_count;
} while (!compare_and_swap(&pa->p_count, oldval, oldval - 1, &pa->p_spinlock));
return oldval;
}
#define ATOMIC_INITIALIZER { 0, 0 }

104
sysdeps/i386/i686/add_n.S Normal file
View File

@ -0,0 +1,104 @@
/* Add two limb vectors of the same length > 0 and store sum in a third
limb vector.
Copyright (C) 1992, 94, 95, 97, 98, 2000 Free Software Foundation, Inc.
This file is part of the GNU MP Library.
The GNU MP Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Library General Public License as published by
the Free Software Foundation; either version 2 of the License, or (at your
option) any later version.
The GNU MP 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 Library General Public
License for more details.
You should have received a copy of the GNU Library General Public License
along with the GNU MP Library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA. */
/*
INPUT PARAMETERS
res_ptr (sp + 4)
s1_ptr (sp + 8)
s2_ptr (sp + 12)
size (sp + 16)
*/
#include "sysdep.h"
#include "asm-syntax.h"
.text
#ifdef PIC
L(1): addl (%esp), %eax
ret
#endif
ENTRY(__mpn_add_n)
pushl %edi
pushl %esi
movl 12(%esp),%edi /* res_ptr */
movl 16(%esp),%esi /* s1_ptr */
movl 20(%esp),%edx /* s2_ptr */
movl 24(%esp),%ecx /* size */
movl %ecx,%eax
shrl $3,%ecx /* compute count for unrolled loop */
negl %eax
andl $7,%eax /* get index where to start loop */
jz L(oop) /* necessary special case for 0 */
incl %ecx /* adjust loop count */
shll $2,%eax /* adjustment for pointers... */
subl %eax,%edi /* ... since they are offset ... */
subl %eax,%esi /* ... by a constant when we ... */
subl %eax,%edx /* ... enter the loop */
shrl $2,%eax /* restore previous value */
#ifdef PIC
/* Calculate start address in loop for PIC. */
leal (L(oop)-L(0)-3)(%eax,%eax,8),%eax
call L(1)
L(0):
#else
/* Calculate start address in loop for non-PIC. */
leal (L(oop) - 3)(%eax,%eax,8),%eax
#endif
jmp *%eax /* jump into loop */
ALIGN (3)
L(oop): movl (%esi),%eax
adcl (%edx),%eax
movl %eax,(%edi)
movl 4(%esi),%eax
adcl 4(%edx),%eax
movl %eax,4(%edi)
movl 8(%esi),%eax
adcl 8(%edx),%eax
movl %eax,8(%edi)
movl 12(%esi),%eax
adcl 12(%edx),%eax
movl %eax,12(%edi)
movl 16(%esi),%eax
adcl 16(%edx),%eax
movl %eax,16(%edi)
movl 20(%esi),%eax
adcl 20(%edx),%eax
movl %eax,20(%edi)
movl 24(%esi),%eax
adcl 24(%edx),%eax
movl %eax,24(%edi)
movl 28(%esi),%eax
adcl 28(%edx),%eax
movl %eax,28(%edi)
leal 32(%edi),%edi
leal 32(%esi),%esi
leal 32(%edx),%edx
decl %ecx
jnz L(oop)
sbbl %eax,%eax
negl %eax
popl %esi
popl %edi
ret
END(__mpn_add_n)