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/*
* Copyright (c) 1994 by Xerox Corporation. All rights reserved.
* Copyright (c) 1996 by Silicon Graphics. All rights reserved.
* Copyright (c) 1998 by Fergus Henderson. All rights reserved.
* Copyright (c) 2000-2005 by Hewlett-Packard Company. All rights reserved.
*
* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
* OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
*
* Permission is hereby granted to use or copy this program
* for any purpose, provided the above notices are retained on all copies.
* Permission to modify the code and to distribute modified code is granted,
* provided the above notices are retained, and a notice that the code was
* modified is included with the above copyright notice.
*/
#include "private/pthread_support.h"
/*
* Support code originally for LinuxThreads, the clone()-based kernel
* thread package for Linux which is included in libc6.
*
* This code no doubt makes some assumptions beyond what is
* guaranteed by the pthread standard, though it now does
* very little of that. It now also supports NPTL, and many
* other Posix thread implementations. We are trying to merge
* all flavors of pthread support code into this file.
*/
/*
* Linux_threads.c now also includes some code to support HPUX and
* OSF1 (Compaq Tru64 Unix, really). The OSF1 support is based on Eric Benson's
* patch.
*
* Eric also suggested an alternate basis for a lock implementation in
* his code:
* + #elif defined(OSF1)
* + unsigned long GC_allocate_lock = 0;
* + msemaphore GC_allocate_semaphore;
* + # define GC_TRY_LOCK() \
* + ((msem_lock(&GC_allocate_semaphore, MSEM_IF_NOWAIT) == 0) \
* + ? (GC_allocate_lock = 1) \
* + : 0)
* + # define GC_LOCK_TAKEN GC_allocate_lock
*/
#if defined(GC_PTHREADS) && !defined(GC_WIN32_THREADS)
# include <stdlib.h>
# include <pthread.h>
# include <sched.h>
# include <time.h>
# include <errno.h>
# include <unistd.h>
# if !defined(GC_RTEMS_PTHREADS)
# include <sys/mman.h>
# endif
# include <sys/time.h>
# include <sys/types.h>
# include <sys/stat.h>
# include <fcntl.h>
# include <signal.h>
# include "gc_inline.h"
#if defined(GC_DARWIN_THREADS)
# include "private/darwin_semaphore.h"
#else
# include <semaphore.h>
#endif /* !GC_DARWIN_THREADS */
#if defined(GC_DARWIN_THREADS) || defined(GC_FREEBSD_THREADS)
# include <sys/sysctl.h>
#endif /* GC_DARWIN_THREADS */
#if defined(GC_NETBSD_THREADS) || defined(GC_OPENBSD_THREADS)
# include <sys/param.h>
# include <sys/sysctl.h>
#endif /* GC_NETBSD_THREADS */
/* Allocator lock definitions. */
#if !defined(USE_SPIN_LOCK)
GC_INNER pthread_mutex_t GC_allocate_ml = PTHREAD_MUTEX_INITIALIZER;
#endif
#ifdef GC_ASSERTIONS
GC_INNER unsigned long GC_lock_holder = NO_THREAD;
/* Used only for assertions. */
#endif
#if defined(GC_DGUX386_THREADS)
# include <sys/dg_sys_info.h>
# include <sys/_int_psem.h>
/* sem_t is an uint in DG/UX */
typedef unsigned int sem_t;
#endif /* GC_DGUX386_THREADS */
/* Undefine macros used to redirect pthread primitives. */
# undef pthread_create
# ifndef GC_NO_PTHREAD_SIGMASK
# undef pthread_sigmask
# endif
# ifndef GC_NO_PTHREAD_CANCEL
# undef pthread_cancel
# endif
# ifdef GC_PTHREAD_EXIT_ATTRIBUTE
# undef pthread_exit
# endif
# undef pthread_join
# undef pthread_detach
# if defined(GC_OSF1_THREADS) && defined(_PTHREAD_USE_MANGLED_NAMES_) \
&& !defined(_PTHREAD_USE_PTDNAM_)
/* Restore the original mangled names on Tru64 UNIX. */
# define pthread_create __pthread_create
# define pthread_join __pthread_join
# define pthread_detach __pthread_detach
# ifndef GC_NO_PTHREAD_CANCEL
# define pthread_cancel __pthread_cancel
# endif
# ifdef GC_PTHREAD_EXIT_ATTRIBUTE
# define pthread_exit __pthread_exit
# endif
# endif
#ifdef GC_USE_LD_WRAP
# define WRAP_FUNC(f) __wrap_##f
# define REAL_FUNC(f) __real_##f
int REAL_FUNC(pthread_create)(pthread_t *,
GC_PTHREAD_CREATE_CONST pthread_attr_t *,
void *(*start_routine)(void *), void *);
int REAL_FUNC(pthread_join)(pthread_t, void **);
int REAL_FUNC(pthread_detach)(pthread_t);
# ifndef GC_NO_PTHREAD_SIGMASK
int REAL_FUNC(pthread_sigmask)(int, const sigset_t *, sigset_t *);
# endif
# ifndef GC_NO_PTHREAD_CANCEL
int REAL_FUNC(pthread_cancel)(pthread_t);
# endif
# ifdef GC_PTHREAD_EXIT_ATTRIBUTE
void REAL_FUNC(pthread_exit)(void *) GC_PTHREAD_EXIT_ATTRIBUTE;
# endif
#else
# ifdef GC_USE_DLOPEN_WRAP
# include <dlfcn.h>
# define WRAP_FUNC(f) f
# define REAL_FUNC(f) GC_real_##f
/* We define both GC_f and plain f to be the wrapped function. */
/* In that way plain calls work, as do calls from files that */
/* included gc.h, which redefined f to GC_f. */
/* FIXME: Needs work for DARWIN and True64 (OSF1) */
typedef int (* GC_pthread_create_t)(pthread_t *,
GC_PTHREAD_CREATE_CONST pthread_attr_t *,
void * (*)(void *), void *);
static GC_pthread_create_t REAL_FUNC(pthread_create);
# ifndef GC_NO_PTHREAD_SIGMASK
typedef int (* GC_pthread_sigmask_t)(int, const sigset_t *,
sigset_t *);
static GC_pthread_sigmask_t REAL_FUNC(pthread_sigmask);
# endif
typedef int (* GC_pthread_join_t)(pthread_t, void **);
static GC_pthread_join_t REAL_FUNC(pthread_join);
typedef int (* GC_pthread_detach_t)(pthread_t);
static GC_pthread_detach_t REAL_FUNC(pthread_detach);
# ifndef GC_NO_PTHREAD_CANCEL
typedef int (* GC_pthread_cancel_t)(pthread_t);
static GC_pthread_cancel_t REAL_FUNC(pthread_cancel);
# endif
# ifdef GC_PTHREAD_EXIT_ATTRIBUTE
typedef void (* GC_pthread_exit_t)(void *) GC_PTHREAD_EXIT_ATTRIBUTE;
static GC_pthread_exit_t REAL_FUNC(pthread_exit);
# endif
# else
# define WRAP_FUNC(f) GC_##f
# if !defined(GC_DGUX386_THREADS)
# define REAL_FUNC(f) f
# else /* GC_DGUX386_THREADS */
# define REAL_FUNC(f) __d10_##f
# endif /* GC_DGUX386_THREADS */
# endif
#endif
#if defined(GC_USE_LD_WRAP) || defined(GC_USE_DLOPEN_WRAP)
/* Define GC_ functions as aliases for the plain ones, which will */
/* be intercepted. This allows files which include gc.h, and hence */
/* generate references to the GC_ symbols, to see the right symbols. */
GC_API int GC_pthread_create(pthread_t * t,
GC_PTHREAD_CREATE_CONST pthread_attr_t *a,
void * (* fn)(void *), void * arg)
{
return pthread_create(t, a, fn, arg);
}
# ifndef GC_NO_PTHREAD_SIGMASK
GC_API int GC_pthread_sigmask(int how, const sigset_t *mask,
sigset_t *old)
{
return pthread_sigmask(how, mask, old);
}
# endif /* !GC_NO_PTHREAD_SIGMASK */
GC_API int GC_pthread_join(pthread_t t, void **res)
{
return pthread_join(t, res);
}
GC_API int GC_pthread_detach(pthread_t t)
{
return pthread_detach(t);
}
# ifndef GC_NO_PTHREAD_CANCEL
GC_API int GC_pthread_cancel(pthread_t t)
{
return pthread_cancel(t);
}
# endif /* !GC_NO_PTHREAD_CANCEL */
# ifdef GC_PTHREAD_EXIT_ATTRIBUTE
GC_API GC_PTHREAD_EXIT_ATTRIBUTE void GC_pthread_exit(void *retval)
{
pthread_exit(retval);
}
# endif /* GC_PTHREAD_EXIT_ATTRIBUTE */
#endif /* Linker-based interception. */
#ifdef GC_USE_DLOPEN_WRAP
STATIC GC_bool GC_syms_initialized = FALSE;
STATIC void GC_init_real_syms(void)
{
void *dl_handle;
if (GC_syms_initialized) return;
# ifdef RTLD_NEXT
dl_handle = RTLD_NEXT;
# else
dl_handle = dlopen("libpthread.so.0", RTLD_LAZY);
if (NULL == dl_handle) {
dl_handle = dlopen("libpthread.so", RTLD_LAZY); /* without ".0" */
}
if (NULL == dl_handle) ABORT("Couldn't open libpthread");
# endif
REAL_FUNC(pthread_create) = (GC_pthread_create_t)
dlsym(dl_handle, "pthread_create");
# ifdef RTLD_NEXT
if (REAL_FUNC(pthread_create) == 0)
ABORT("pthread_create not found"
" (probably -lgc is specified after -lpthread)");
# endif
# ifndef GC_NO_PTHREAD_SIGMASK
REAL_FUNC(pthread_sigmask) = (GC_pthread_sigmask_t)
dlsym(dl_handle, "pthread_sigmask");
# endif
REAL_FUNC(pthread_join) = (GC_pthread_join_t)
dlsym(dl_handle, "pthread_join");
REAL_FUNC(pthread_detach) = (GC_pthread_detach_t)
dlsym(dl_handle, "pthread_detach");
# ifndef GC_NO_PTHREAD_CANCEL
REAL_FUNC(pthread_cancel) = (GC_pthread_cancel_t)
dlsym(dl_handle, "pthread_cancel");
# endif
# ifdef GC_PTHREAD_EXIT_ATTRIBUTE
REAL_FUNC(pthread_exit) = (GC_pthread_exit_t)
dlsym(dl_handle, "pthread_exit");
# endif
GC_syms_initialized = TRUE;
}
# define INIT_REAL_SYMS() if (EXPECT(GC_syms_initialized, TRUE)) {} \
else GC_init_real_syms()
#else
# define INIT_REAL_SYMS() (void)0
#endif
static GC_bool parallel_initialized = FALSE;
GC_INNER GC_bool GC_need_to_lock = FALSE;
STATIC int GC_nprocs = 1;
/* Number of processors. We may not have */
/* access to all of them, but this is as good */
/* a guess as any ... */
#ifdef THREAD_LOCAL_ALLOC
/* We must explicitly mark ptrfree and gcj free lists, since the free */
/* list links wouldn't otherwise be found. We also set them in the */
/* normal free lists, since that involves touching less memory than */
/* if we scanned them normally. */
GC_INNER void GC_mark_thread_local_free_lists(void)
{
int i;
GC_thread p;
for (i = 0; i < THREAD_TABLE_SZ; ++i) {
for (p = GC_threads[i]; 0 != p; p = p -> next) {
if (!(p -> flags & FINISHED))
GC_mark_thread_local_fls_for(&(p->tlfs));
}
}
}
# if defined(GC_ASSERTIONS)
void GC_check_tls_for(GC_tlfs p);
# if defined(USE_CUSTOM_SPECIFIC)
void GC_check_tsd_marks(tsd *key);
# endif
/* Check that all thread-local free-lists are completely marked. */
/* Also check that thread-specific-data structures are marked. */
void GC_check_tls(void)
{
int i;
GC_thread p;
for (i = 0; i < THREAD_TABLE_SZ; ++i) {
for (p = GC_threads[i]; 0 != p; p = p -> next) {
if (!(p -> flags & FINISHED))
GC_check_tls_for(&(p->tlfs));
}
}
# if defined(USE_CUSTOM_SPECIFIC)
if (GC_thread_key != 0)
GC_check_tsd_marks(GC_thread_key);
# endif
}
# endif /* GC_ASSERTIONS */
#endif /* THREAD_LOCAL_ALLOC */
#ifdef PARALLEL_MARK
# ifndef MAX_MARKERS
# define MAX_MARKERS 16
# endif
static ptr_t marker_sp[MAX_MARKERS - 1] = {0};
#ifdef IA64
static ptr_t marker_bsp[MAX_MARKERS - 1] = {0};
#endif
#if defined(GC_DARWIN_THREADS) && !defined(GC_NO_THREADS_DISCOVERY)
static mach_port_t marker_mach_threads[MAX_MARKERS - 1] = {0};
/* Used only by GC_suspend_thread_list(). */
GC_INNER GC_bool GC_is_mach_marker(thread_act_t thread)
{
int i;
for (i = 0; i < GC_markers_m1; i++) {
if (marker_mach_threads[i] == thread)
return TRUE;
}
return FALSE;
}
#endif /* GC_DARWIN_THREADS */
STATIC void * GC_mark_thread(void * id)
{
word my_mark_no = 0;
IF_CANCEL(int cancel_state;)
if ((word)id == (word)-1) return 0; /* to make compiler happy */
DISABLE_CANCEL(cancel_state);
/* Mark threads are not cancellable; they */
/* should be invisible to client. */
marker_sp[(word)id] = GC_approx_sp();
# ifdef IA64
marker_bsp[(word)id] = GC_save_regs_in_stack();
# endif
# if defined(GC_DARWIN_THREADS) && !defined(GC_NO_THREADS_DISCOVERY)
marker_mach_threads[(word)id] = mach_thread_self();
# endif
for (;; ++my_mark_no) {
/* GC_mark_no is passed only to allow GC_help_marker to terminate */
/* promptly. This is important if it were called from the signal */
/* handler or from the GC lock acquisition code. Under Linux, it's */
/* not safe to call it from a signal handler, since it uses mutexes */
/* and condition variables. Since it is called only here, the */
/* argument is unnecessary. */
if (my_mark_no < GC_mark_no || my_mark_no > GC_mark_no + 2) {
/* resynchronize if we get far off, e.g. because GC_mark_no */
/* wrapped. */
my_mark_no = GC_mark_no;
}
# ifdef DEBUG_THREADS
GC_log_printf("Starting mark helper for mark number %lu\n",
(unsigned long)my_mark_no);
# endif
GC_help_marker(my_mark_no);
}
}
STATIC pthread_t GC_mark_threads[MAX_MARKERS];
#ifdef CAN_HANDLE_FORK
static int available_markers_m1 = 0;
# define start_mark_threads GC_start_mark_threads
GC_API void GC_CALL
#else
# define available_markers_m1 GC_markers_m1
static void
#endif
start_mark_threads(void)
{
int i;
pthread_attr_t attr;
GC_ASSERT(I_DONT_HOLD_LOCK());
# ifdef CAN_HANDLE_FORK
if (available_markers_m1 <= 0 || GC_parallel) return;
/* Skip if parallel markers disabled or already started. */
# endif
INIT_REAL_SYMS(); /* for pthread_create */
if (0 != pthread_attr_init(&attr)) ABORT("pthread_attr_init failed");
if (0 != pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED))
ABORT("pthread_attr_setdetachstate failed");
# if defined(HPUX) || defined(GC_DGUX386_THREADS)
/* Default stack size is usually too small: fix it. */
/* Otherwise marker threads or GC may run out of */
/* space. */
# define MIN_STACK_SIZE (8*HBLKSIZE*sizeof(word))
{
size_t old_size;
if (pthread_attr_getstacksize(&attr, &old_size) != 0)
ABORT("pthread_attr_getstacksize failed");
if (old_size < MIN_STACK_SIZE) {
if (pthread_attr_setstacksize(&attr, MIN_STACK_SIZE) != 0)
ABORT("pthread_attr_setstacksize failed");
}
}
# endif /* HPUX || GC_DGUX386_THREADS */
for (i = 0; i < available_markers_m1; ++i) {
if (0 != REAL_FUNC(pthread_create)(GC_mark_threads + i, &attr,
GC_mark_thread, (void *)(word)i)) {
WARN("Marker thread creation failed, errno = %" WARN_PRIdPTR "\n",
errno);
/* Don't try to create other marker threads. */
break;
}
}
GC_markers_m1 = i;
pthread_attr_destroy(&attr);
GC_COND_LOG_PRINTF("Started %d mark helper threads\n", GC_markers_m1);
}
#endif /* PARALLEL_MARK */
GC_INNER GC_bool GC_thr_initialized = FALSE;
GC_INNER volatile GC_thread GC_threads[THREAD_TABLE_SZ] = {0};
void GC_push_thread_structures(void)
{
GC_ASSERT(I_HOLD_LOCK());
GC_push_all((ptr_t)(GC_threads), (ptr_t)(GC_threads)+sizeof(GC_threads));
# if defined(THREAD_LOCAL_ALLOC)
GC_push_all((ptr_t)(&GC_thread_key),
(ptr_t)(&GC_thread_key) + sizeof(GC_thread_key));
# endif
}
#ifdef DEBUG_THREADS
STATIC int GC_count_threads(void)
{
int i;
int count = 0;
GC_ASSERT(I_HOLD_LOCK());
for (i = 0; i < THREAD_TABLE_SZ; ++i) {
GC_thread th = GC_threads[i];
while (th) {
if (!(th->flags & FINISHED))
++count;
th = th->next;
}
}
return count;
}
#endif /* DEBUG_THREADS */
/* It may not be safe to allocate when we register the first thread. */
static struct GC_Thread_Rep first_thread;
/* Add a thread to GC_threads. We assume it wasn't already there. */
/* Caller holds allocation lock. */
STATIC GC_thread GC_new_thread(pthread_t id)
{
int hv = NUMERIC_THREAD_ID(id) % THREAD_TABLE_SZ;
GC_thread result;
static GC_bool first_thread_used = FALSE;
# ifdef DEBUG_THREADS
GC_log_printf("Creating thread %p\n", (void *)id);
# endif
GC_ASSERT(I_HOLD_LOCK());
if (!EXPECT(first_thread_used, TRUE)) {
result = &first_thread;
first_thread_used = TRUE;
} else {
result = (struct GC_Thread_Rep *)
GC_INTERNAL_MALLOC(sizeof(struct GC_Thread_Rep), NORMAL);
if (result == 0) return(0);
}
result -> id = id;
# ifdef PLATFORM_ANDROID
result -> kernel_id = gettid();
# endif
result -> next = GC_threads[hv];
GC_threads[hv] = result;
# ifdef NACL
GC_nacl_gc_thread_self = result;
GC_nacl_initialize_gc_thread();
# endif
GC_ASSERT(result -> flags == 0 && result -> thread_blocked == 0);
return(result);
}
/* Delete a thread from GC_threads. We assume it is there. */
/* (The code intentionally traps if it wasn't.) */
/* It is safe to delete the main thread. */
STATIC void GC_delete_thread(pthread_t id)
{
int hv = NUMERIC_THREAD_ID(id) % THREAD_TABLE_SZ;
register GC_thread p = GC_threads[hv];
register GC_thread prev = 0;
# ifdef DEBUG_THREADS
GC_log_printf("Deleting thread %p, n_threads = %d\n",
(void *)id, GC_count_threads());
# endif
# ifdef NACL
GC_nacl_shutdown_gc_thread();
GC_nacl_gc_thread_self = NULL;
# endif
GC_ASSERT(I_HOLD_LOCK());
while (!THREAD_EQUAL(p -> id, id)) {
prev = p;
p = p -> next;
}
if (prev == 0) {
GC_threads[hv] = p -> next;
} else {
prev -> next = p -> next;
}
if (p != &first_thread) {
# ifdef GC_DARWIN_THREADS
mach_port_deallocate(mach_task_self(), p->stop_info.mach_thread);
# endif
GC_INTERNAL_FREE(p);
}
}
/* If a thread has been joined, but we have not yet */
/* been notified, then there may be more than one thread */
/* in the table with the same pthread id. */
/* This is OK, but we need a way to delete a specific one. */
STATIC void GC_delete_gc_thread(GC_thread t)
{
pthread_t id = t -> id;
int hv = NUMERIC_THREAD_ID(id) % THREAD_TABLE_SZ;
register GC_thread p = GC_threads[hv];
register GC_thread prev = 0;
GC_ASSERT(I_HOLD_LOCK());
while (p != t) {
prev = p;
p = p -> next;
}
if (prev == 0) {
GC_threads[hv] = p -> next;
} else {
prev -> next = p -> next;
}
# ifdef GC_DARWIN_THREADS
mach_port_deallocate(mach_task_self(), p->stop_info.mach_thread);
# endif
GC_INTERNAL_FREE(p);
# ifdef DEBUG_THREADS
GC_log_printf("Deleted thread %p, n_threads = %d\n",
(void *)id, GC_count_threads());
# endif
}
/* Return a GC_thread corresponding to a given pthread_t. */
/* Returns 0 if it's not there. */
/* Caller holds allocation lock or otherwise inhibits */
/* updates. */
/* If there is more than one thread with the given id we */
/* return the most recent one. */
GC_INNER GC_thread GC_lookup_thread(pthread_t id)
{
int hv = NUMERIC_THREAD_ID(id) % THREAD_TABLE_SZ;
register GC_thread p = GC_threads[hv];
while (p != 0 && !THREAD_EQUAL(p -> id, id)) p = p -> next;
return(p);
}
/* Called by GC_finalize() (in case of an allocation failure observed). */
GC_INNER void GC_reset_finalizer_nested(void)
{
GC_thread me = GC_lookup_thread(pthread_self());
me->finalizer_nested = 0;
}
/* Checks and updates the thread-local level of finalizers recursion. */
/* Returns NULL if GC_invoke_finalizers() should not be called by the */
/* collector (to minimize the risk of a deep finalizers recursion), */
/* otherwise returns a pointer to the thread-local finalizer_nested. */
/* Called by GC_notify_or_invoke_finalizers() only (the lock is held). */
GC_INNER unsigned char *GC_check_finalizer_nested(void)
{
GC_thread me = GC_lookup_thread(pthread_self());
unsigned nesting_level = me->finalizer_nested;
if (nesting_level) {
/* We are inside another GC_invoke_finalizers(). */
/* Skip some implicitly-called GC_invoke_finalizers() */
/* depending on the nesting (recursion) level. */
if (++me->finalizer_skipped < (1U << nesting_level)) return NULL;
me->finalizer_skipped = 0;
}
me->finalizer_nested = (unsigned char)(nesting_level + 1);
return &me->finalizer_nested;
}
#if defined(GC_ASSERTIONS) && defined(THREAD_LOCAL_ALLOC)
/* This is called from thread-local GC_malloc(). */
GC_bool GC_is_thread_tsd_valid(void *tsd)
{
GC_thread me;
DCL_LOCK_STATE;
LOCK();
me = GC_lookup_thread(pthread_self());
UNLOCK();
return (word)tsd >= (word)(&me->tlfs)
&& (word)tsd < (word)(&me->tlfs) + sizeof(me->tlfs);
}
#endif /* GC_ASSERTIONS && THREAD_LOCAL_ALLOC */
GC_API int GC_CALL GC_thread_is_registered(void)
{
pthread_t self = pthread_self();
GC_thread me;
DCL_LOCK_STATE;
LOCK();
me = GC_lookup_thread(self);
UNLOCK();
return me != NULL;
}
#ifdef CAN_HANDLE_FORK
/* Remove all entries from the GC_threads table, except the */
/* one for the current thread. We need to do this in the child */
/* process after a fork(), since only the current thread */
/* survives in the child. */
STATIC void GC_remove_all_threads_but_me(void)
{
pthread_t self = pthread_self();
int hv;
GC_thread p, next, me;
for (hv = 0; hv < THREAD_TABLE_SZ; ++hv) {
me = 0;
for (p = GC_threads[hv]; 0 != p; p = next) {
next = p -> next;
if (THREAD_EQUAL(p -> id, self)) {
me = p;
p -> next = 0;
# ifdef GC_DARWIN_THREADS
/* Update thread Id after fork (it is OK to call */
/* GC_destroy_thread_local and GC_free_internal */
/* before update). */
me -> stop_info.mach_thread = mach_thread_self();
# elif defined(PLATFORM_ANDROID)
me -> kernel_id = gettid();
# endif
# if defined(THREAD_LOCAL_ALLOC) && !defined(USE_CUSTOM_SPECIFIC)
/* Some TLS implementations might be not fork-friendly, so */
/* we re-assign thread-local pointer to 'tlfs' for safety */
/* instead of the assertion check (again, it is OK to call */
/* GC_destroy_thread_local and GC_free_internal before). */
if (GC_setspecific(GC_thread_key, &me->tlfs) != 0)
ABORT("GC_setspecific failed (in child)");
# endif
} else {
# ifdef THREAD_LOCAL_ALLOC
if (!(p -> flags & FINISHED)) {
GC_destroy_thread_local(&(p->tlfs));
GC_remove_specific(GC_thread_key);
}
# endif
if (p != &first_thread) GC_INTERNAL_FREE(p);
}
}
GC_threads[hv] = me;
}
}
#endif /* CAN_HANDLE_FORK */
#ifdef USE_PROC_FOR_LIBRARIES
GC_INNER GC_bool GC_segment_is_thread_stack(ptr_t lo, ptr_t hi)
{
int i;
GC_thread p;
GC_ASSERT(I_HOLD_LOCK());
# ifdef PARALLEL_MARK
for (i = 0; i < GC_markers_m1; ++i) {
if ((word)marker_sp[i] > (word)lo && (word)marker_sp[i] < (word)hi)
return TRUE;
# ifdef IA64
if ((word)marker_bsp[i] > (word)lo
&& (word)marker_bsp[i] < (word)hi)
return TRUE;
# endif
}
# endif
for (i = 0; i < THREAD_TABLE_SZ; i++) {
for (p = GC_threads[i]; p != 0; p = p -> next) {
if (0 != p -> stack_end) {
# ifdef STACK_GROWS_UP
if ((word)p->stack_end >= (word)lo
&& (word)p->stack_end < (word)hi)
return TRUE;
# else /* STACK_GROWS_DOWN */
if ((word)p->stack_end > (word)lo
&& (word)p->stack_end <= (word)hi)
return TRUE;
# endif
}
}
}
return FALSE;
}
#endif /* USE_PROC_FOR_LIBRARIES */
#ifdef IA64
/* Find the largest stack_base smaller than bound. May be used */
/* to find the boundary between a register stack and adjacent */
/* immediately preceding memory stack. */
GC_INNER ptr_t GC_greatest_stack_base_below(ptr_t bound)
{
int i;
GC_thread p;
ptr_t result = 0;
GC_ASSERT(I_HOLD_LOCK());
# ifdef PARALLEL_MARK
for (i = 0; i < GC_markers_m1; ++i) {
if ((word)marker_sp[i] > (word)result
&& (word)marker_sp[i] < (word)bound)
result = marker_sp[i];
}
# endif
for (i = 0; i < THREAD_TABLE_SZ; i++) {
for (p = GC_threads[i]; p != 0; p = p -> next) {
if ((word)p->stack_end > (word)result
&& (word)p->stack_end < (word)bound) {
result = p -> stack_end;
}
}
}
return result;
}
#endif /* IA64 */
#ifndef STAT_READ
/* Also defined in os_dep.c. */
# define STAT_BUF_SIZE 4096
# define STAT_READ read
/* If read is wrapped, this may need to be redefined to call */
/* the real one. */
#endif
#ifdef GC_HPUX_THREADS
# define GC_get_nprocs() pthread_num_processors_np()
#elif defined(GC_OSF1_THREADS) || defined(GC_AIX_THREADS) \
|| defined(GC_SOLARIS_THREADS) || defined(GC_GNU_THREADS) \
|| defined(PLATFORM_ANDROID) || defined(NACL)
GC_INLINE int GC_get_nprocs(void)
{
int nprocs = (int)sysconf(_SC_NPROCESSORS_ONLN);
return nprocs > 0 ? nprocs : 1; /* ignore error silently */
}
#elif defined(GC_IRIX_THREADS)
GC_INLINE int GC_get_nprocs(void)
{
int nprocs = (int)sysconf(_SC_NPROC_ONLN);
return nprocs > 0 ? nprocs : 1; /* ignore error silently */
}
#elif defined(GC_LINUX_THREADS) /* && !PLATFORM_ANDROID && !NACL */
/* Return the number of processors. */
STATIC int GC_get_nprocs(void)
{
/* Should be "return sysconf(_SC_NPROCESSORS_ONLN);" but that */
/* appears to be buggy in many cases. */
/* We look for lines "cpu<n>" in /proc/stat. */
char stat_buf[STAT_BUF_SIZE];
int f;
int result, i, len;
f = open("/proc/stat", O_RDONLY);
if (f < 0) {
WARN("Couldn't read /proc/stat\n", 0);
return 1; /* assume an uniprocessor */
}
len = STAT_READ(f, stat_buf, STAT_BUF_SIZE);
close(f);
result = 1;
/* Some old kernels only have a single "cpu nnnn ..." */
/* entry in /proc/stat. We identify those as */
/* uniprocessors. */
for (i = 0; i < len - 100; ++i) {
if (stat_buf[i] == '\n' && stat_buf[i+1] == 'c'
&& stat_buf[i+2] == 'p' && stat_buf[i+3] == 'u') {
int cpu_no = atoi(&stat_buf[i + 4]);
if (cpu_no >= result)
result = cpu_no + 1;
}
}
return result;
}
#elif defined(GC_DGUX386_THREADS)
/* Return the number of processors, or i <= 0 if it can't be determined. */
STATIC int GC_get_nprocs(void)
{
int numCpus;
struct dg_sys_info_pm_info pm_sysinfo;
int status = 0;
status = dg_sys_info((long int *) &pm_sysinfo,
DG_SYS_INFO_PM_INFO_TYPE, DG_SYS_INFO_PM_CURRENT_VERSION);
if (status < 0)
/* set -1 for error */
numCpus = -1;
else
/* Active CPUs */
numCpus = pm_sysinfo.idle_vp_count;
return(numCpus);
}
#elif defined(GC_DARWIN_THREADS) || defined(GC_FREEBSD_THREADS) \
|| defined(GC_NETBSD_THREADS) || defined(GC_OPENBSD_THREADS)
STATIC int GC_get_nprocs(void)
{
int mib[] = {CTL_HW,HW_NCPU};
int res;
size_t len = sizeof(res);
sysctl(mib, sizeof(mib)/sizeof(int), &res, &len, NULL, 0);
return res;
}
#else
/* E.g., GC_RTEMS_PTHREADS */
# define GC_get_nprocs() 1 /* not implemented */
#endif /* !GC_LINUX_THREADS && !GC_DARWIN_THREADS && ... */
#if defined(ARM32) && defined(GC_LINUX_THREADS) && !defined(NACL)
/* Some buggy Linux/arm kernels show only non-sleeping CPUs in */
/* /proc/stat (and /proc/cpuinfo), so another data system source is */
/* tried first. Result <= 0 on error. */
STATIC int GC_get_nprocs_present(void)
{
char stat_buf[16];
int f;
int len;
f = open("/sys/devices/system/cpu/present", O_RDONLY);
if (f < 0)
return -1; /* cannot open the file */
len = STAT_READ(f, stat_buf, sizeof(stat_buf));
close(f);
/* Recognized file format: "0\n" or "0-<max_cpu_id>\n" */
/* The file might probably contain a comma-separated list */
/* but we do not need to handle it (just silently ignore). */
if (len < 2 || stat_buf[0] != '0' || stat_buf[len - 1] != '\n') {
return 0; /* read error or unrecognized content */
} else if (len == 2) {
return 1; /* an uniprocessor */
} else if (stat_buf[1] != '-') {
return 0; /* unrecognized content */
}
stat_buf[len - 1] = '\0'; /* terminate the string */
return atoi(&stat_buf[2]) + 1; /* skip "0-" and parse max_cpu_num */
}
#endif /* ARM32 && GC_LINUX_THREADS && !NACL */
/* We hold the GC lock. Wait until an in-progress GC has finished. */
/* Repeatedly RELEASES GC LOCK in order to wait. */
/* If wait_for_all is true, then we exit with the GC lock held and no */
/* collection in progress; otherwise we just wait for the current GC */
/* to finish. */
STATIC void GC_wait_for_gc_completion(GC_bool wait_for_all)
{
DCL_LOCK_STATE;
GC_ASSERT(I_HOLD_LOCK());
ASSERT_CANCEL_DISABLED();
if (GC_incremental && GC_collection_in_progress()) {
word old_gc_no = GC_gc_no;
/* Make sure that no part of our stack is still on the mark stack, */
/* since it's about to be unmapped. */
while (GC_incremental && GC_collection_in_progress()
&& (wait_for_all || old_gc_no == GC_gc_no)) {
ENTER_GC();
GC_in_thread_creation = TRUE;
GC_collect_a_little_inner(1);
GC_in_thread_creation = FALSE;
EXIT_GC();
UNLOCK();
sched_yield();
LOCK();
}
}
}
#ifdef CAN_HANDLE_FORK
/* Procedures called before and after a fork. The goal here is to make */
/* it safe to call GC_malloc() in a forked child. It's unclear that is */
/* attainable, since the single UNIX spec seems to imply that one */
/* should only call async-signal-safe functions, and we probably can't */
/* quite guarantee that. But we give it our best shot. (That same */
/* spec also implies that it's not safe to call the system malloc */
/* between fork() and exec(). Thus we're doing no worse than it.) */
IF_CANCEL(static int fork_cancel_state;)
/* protected by allocation lock. */
/* Called before a fork() */
static void fork_prepare_proc(void)
{
/* Acquire all relevant locks, so that after releasing the locks */
/* the child will see a consistent state in which monitor */
/* invariants hold. Unfortunately, we can't acquire libc locks */
/* we might need, and there seems to be no guarantee that libc */
/* must install a suitable fork handler. */
/* Wait for an ongoing GC to finish, since we can't finish it in */
/* the (one remaining thread in) the child. */
LOCK();
DISABLE_CANCEL(fork_cancel_state);
/* Following waits may include cancellation points. */
# if defined(PARALLEL_MARK)
if (GC_parallel)
GC_wait_for_reclaim();
# endif
GC_wait_for_gc_completion(TRUE);
# if defined(PARALLEL_MARK)
if (GC_parallel)
GC_acquire_mark_lock();
# endif
}
/* Called in parent after a fork() (even if the latter failed). */
static void fork_parent_proc(void)
{
# if defined(PARALLEL_MARK)
if (GC_parallel)
GC_release_mark_lock();
# endif
RESTORE_CANCEL(fork_cancel_state);
UNLOCK();
}
/* Called in child after a fork() */
static void fork_child_proc(void)
{
/* Clean up the thread table, so that just our thread is left. */
# if defined(PARALLEL_MARK)
if (GC_parallel)
GC_release_mark_lock();
# endif
GC_remove_all_threads_but_me();
# ifdef PARALLEL_MARK
/* Turn off parallel marking in the child, since we are probably */
/* just going to exec, and we would have to restart mark threads. */
GC_parallel = FALSE;
# endif /* PARALLEL_MARK */
RESTORE_CANCEL(fork_cancel_state);
UNLOCK();
}
/* Routines for fork handling by client (no-op if pthread_atfork works). */
GC_API void GC_CALL GC_atfork_prepare(void)
{
# if defined(GC_DARWIN_THREADS) && defined(MPROTECT_VDB)
if (GC_dirty_maintained) {
GC_ASSERT(0 == GC_handle_fork);
ABORT("Unable to fork while mprotect_thread is running");
}
# endif
if (GC_handle_fork <= 0)
fork_prepare_proc();
}
GC_API void GC_CALL GC_atfork_parent(void)
{
if (GC_handle_fork <= 0)
fork_parent_proc();
}
GC_API void GC_CALL GC_atfork_child(void)
{
if (GC_handle_fork <= 0)
fork_child_proc();
}
#endif /* CAN_HANDLE_FORK */
#ifdef INCLUDE_LINUX_THREAD_DESCR
__thread int GC_dummy_thread_local;
GC_INNER GC_bool GC_enclosing_mapping(ptr_t addr,
ptr_t *startp, ptr_t *endp);
#endif
/* We hold the allocation lock. */
GC_INNER void GC_thr_init(void)
{
if (GC_thr_initialized) return;
GC_thr_initialized = TRUE;
GC_ASSERT((word)&GC_threads % sizeof(word) == 0);
# ifdef CAN_HANDLE_FORK
/* Prepare for forks if requested. */
if (GC_handle_fork) {
# ifdef CAN_CALL_ATFORK
if (pthread_atfork(fork_prepare_proc, fork_parent_proc,
fork_child_proc) == 0) {
/* Handlers successfully registered. */
GC_handle_fork = 1;
} else
# endif
/* else */ if (GC_handle_fork != -1)
ABORT("pthread_atfork failed");
}
# endif
# ifdef INCLUDE_LINUX_THREAD_DESCR
/* Explicitly register the region including the address */
/* of a thread local variable. This should include thread */
/* locals for the main thread, except for those allocated */
/* in response to dlopen calls. */
{
ptr_t thread_local_addr = (ptr_t)(&GC_dummy_thread_local);
ptr_t main_thread_start, main_thread_end;
if (!GC_enclosing_mapping(thread_local_addr, &main_thread_start,
&main_thread_end)) {
ABORT("Failed to find mapping for main thread thread locals");
} else {
/* main_thread_start and main_thread_end are initialized. */
GC_add_roots_inner(main_thread_start, main_thread_end, FALSE);
}
}
# endif
/* Add the initial thread, so we can stop it. */
{
GC_thread t = GC_new_thread(pthread_self());
if (t == NULL)
ABORT("Failed to allocate memory for the initial thread");
# ifdef GC_DARWIN_THREADS
t -> stop_info.mach_thread = mach_thread_self();
# else
t -> stop_info.stack_ptr = GC_approx_sp();
# endif
t -> flags = DETACHED | MAIN_THREAD;
}
# ifndef GC_DARWIN_THREADS
GC_stop_init();
# endif
/* Set GC_nprocs. */
{
char * nprocs_string = GETENV("GC_NPROCS");
GC_nprocs = -1;
if (nprocs_string != NULL) GC_nprocs = atoi(nprocs_string);
}
if (GC_nprocs <= 0
# if defined(ARM32) && defined(GC_LINUX_THREADS) && !defined(NACL)
&& (GC_nprocs = GC_get_nprocs_present()) <= 1
/* Workaround for some Linux/arm kernels */
# endif
)
{
GC_nprocs = GC_get_nprocs();
}
if (GC_nprocs <= 0) {
WARN("GC_get_nprocs() returned %" WARN_PRIdPTR "\n", GC_nprocs);
GC_nprocs = 2; /* assume dual-core */
# ifdef PARALLEL_MARK
available_markers_m1 = 0; /* but use only one marker */
# endif
} else {
# ifdef PARALLEL_MARK
{
char * markers_string = GETENV("GC_MARKERS");
int markers_m1;
if (markers_string != NULL) {
markers_m1 = atoi(markers_string) - 1;
if (markers_m1 >= MAX_MARKERS) {
WARN("Limiting number of mark threads\n", 0);
markers_m1 = MAX_MARKERS - 1;
}
} else {
markers_m1 = GC_nprocs - 1;
# ifdef GC_MIN_MARKERS
/* This is primarily for targets without getenv(). */
if (markers_m1 < GC_MIN_MARKERS - 1)
markers_m1 = GC_MIN_MARKERS - 1;
# endif
if (markers_m1 >= MAX_MARKERS)
markers_m1 = MAX_MARKERS - 1; /* silently limit the value */
}
available_markers_m1 = markers_m1;
}
# endif
}
GC_COND_LOG_PRINTF("Number of processors = %d\n", GC_nprocs);
# ifdef PARALLEL_MARK
if (available_markers_m1 <= 0) {
/* Disable parallel marking. */
GC_parallel = FALSE;
GC_COND_LOG_PRINTF(
"Single marker thread, turning off parallel marking\n");
} else {
/* Disable true incremental collection, but generational is OK. */
GC_time_limit = GC_TIME_UNLIMITED;
/* If we are using a parallel marker, actually start helper threads. */
start_mark_threads();
}
# endif
}
/* Perform all initializations, including those that */
/* may require allocation. */
/* Called without allocation lock. */
/* Must be called before a second thread is created. */
/* Did we say it's called without the allocation lock? */
GC_INNER void GC_init_parallel(void)
{
# if defined(THREAD_LOCAL_ALLOC)
DCL_LOCK_STATE;
# endif
if (parallel_initialized) return;
parallel_initialized = TRUE;
/* GC_init() calls us back, so set flag first. */
if (!GC_is_initialized) GC_init();
/* Initialize thread local free lists if used. */
# if defined(THREAD_LOCAL_ALLOC)
LOCK();
GC_init_thread_local(&(GC_lookup_thread(pthread_self())->tlfs));
UNLOCK();
# endif
}
#ifndef GC_NO_PTHREAD_SIGMASK
GC_API int WRAP_FUNC(pthread_sigmask)(int how, const sigset_t *set,
sigset_t *oset)
{
sigset_t fudged_set;
int sig_suspend;
INIT_REAL_SYMS();
if (set != NULL && (how == SIG_BLOCK || how == SIG_SETMASK)) {
fudged_set = *set;
sig_suspend = GC_get_suspend_signal();
GC_ASSERT(sig_suspend >= 0);
sigdelset(&fudged_set, sig_suspend);
set = &fudged_set;
}
return(REAL_FUNC(pthread_sigmask)(how, set, oset));
}
#endif /* !GC_NO_PTHREAD_SIGMASK */
/* Wrapper for functions that are likely to block for an appreciable */
/* length of time. */
GC_INNER void GC_do_blocking_inner(ptr_t data, void * context GC_ATTR_UNUSED)
{
struct blocking_data * d = (struct blocking_data *) data;
pthread_t self = pthread_self();
GC_thread me;
# if defined(SPARC) || defined(IA64)
ptr_t stack_ptr = GC_save_regs_in_stack();
# endif
# if defined(GC_DARWIN_THREADS) && !defined(DARWIN_DONT_PARSE_STACK)
GC_bool topOfStackUnset = FALSE;
# endif
DCL_LOCK_STATE;
LOCK();
me = GC_lookup_thread(self);
GC_ASSERT(!(me -> thread_blocked));
# ifdef SPARC
me -> stop_info.stack_ptr = stack_ptr;
# else
me -> stop_info.stack_ptr = GC_approx_sp();
# endif
# if defined(GC_DARWIN_THREADS) && !defined(DARWIN_DONT_PARSE_STACK)
if (me -> topOfStack == NULL) {
/* GC_do_blocking_inner is not called recursively, */
/* so topOfStack should be computed now. */
topOfStackUnset = TRUE;
me -> topOfStack = GC_FindTopOfStack(0);
}
# endif
# ifdef IA64
me -> backing_store_ptr = stack_ptr;
# endif
me -> thread_blocked = (unsigned char)TRUE;
/* Save context here if we want to support precise stack marking */
UNLOCK();
d -> client_data = (d -> fn)(d -> client_data);
LOCK(); /* This will block if the world is stopped. */
me -> thread_blocked = FALSE;
# if defined(GC_DARWIN_THREADS) && !defined(DARWIN_DONT_PARSE_STACK)
if (topOfStackUnset)
me -> topOfStack = NULL; /* make topOfStack unset again */
# endif
UNLOCK();
}
/* GC_call_with_gc_active() has the opposite to GC_do_blocking() */
/* functionality. It might be called from a user function invoked by */
/* GC_do_blocking() to temporarily back allow calling any GC function */
/* and/or manipulating pointers to the garbage collected heap. */
GC_API void * GC_CALL GC_call_with_gc_active(GC_fn_type fn,
void * client_data)
{
struct GC_traced_stack_sect_s stacksect;
pthread_t self = pthread_self();
GC_thread me;
DCL_LOCK_STATE;
LOCK(); /* This will block if the world is stopped. */
me = GC_lookup_thread(self);
/* Adjust our stack base value (this could happen unless */
/* GC_get_stack_base() was used which returned GC_SUCCESS). */
if ((me -> flags & MAIN_THREAD) == 0) {
GC_ASSERT(me -> stack_end != NULL);
if ((word)me->stack_end HOTTER_THAN (word)(&stacksect))
me -> stack_end = (ptr_t)(&stacksect);
} else {
/* The original stack. */
if ((word)GC_stackbottom HOTTER_THAN (word)(&stacksect))
GC_stackbottom = (ptr_t)(&stacksect);
}
if (!me->thread_blocked) {
/* We are not inside GC_do_blocking() - do nothing more. */
UNLOCK();
client_data = fn(client_data);
/* Prevent treating the above as a tail call. */
GC_noop1((word)(&stacksect));
return client_data; /* result */
}
/* Setup new "stack section". */
stacksect.saved_stack_ptr = me -> stop_info.stack_ptr;
# ifdef IA64
/* This is the same as in GC_call_with_stack_base(). */
stacksect.backing_store_end = GC_save_regs_in_stack();
/* Unnecessarily flushes register stack, */
/* but that probably doesn't hurt. */
stacksect.saved_backing_store_ptr = me -> backing_store_ptr;
# endif
stacksect.prev = me -> traced_stack_sect;
me -> thread_blocked = FALSE;
me -> traced_stack_sect = &stacksect;
UNLOCK();
client_data = fn(client_data);
GC_ASSERT(me -> thread_blocked == FALSE);
GC_ASSERT(me -> traced_stack_sect == &stacksect);
/* Restore original "stack section". */
LOCK();
me -> traced_stack_sect = stacksect.prev;
# ifdef IA64
me -> backing_store_ptr = stacksect.saved_backing_store_ptr;
# endif
me -> thread_blocked = (unsigned char)TRUE;
me -> stop_info.stack_ptr = stacksect.saved_stack_ptr;
UNLOCK();
return client_data; /* result */
}
STATIC void GC_unregister_my_thread_inner(GC_thread me)
{
# ifdef DEBUG_THREADS
GC_log_printf(
"Unregistering thread %p, gc_thread = %p, n_threads = %d\n",
(void *)me->id, me, GC_count_threads());
# endif
GC_ASSERT(!(me -> flags & FINISHED));
# if defined(THREAD_LOCAL_ALLOC)
GC_ASSERT(GC_getspecific(GC_thread_key) == &me->tlfs);
GC_destroy_thread_local(&(me->tlfs));
# endif
# if defined(GC_PTHREAD_EXIT_ATTRIBUTE) || !defined(GC_NO_PTHREAD_CANCEL)
/* Handle DISABLED_GC flag which is set by the */
/* intercepted pthread_cancel or pthread_exit. */
if ((me -> flags & DISABLED_GC) != 0) {
GC_dont_gc--;
}
# endif
if (me -> flags & DETACHED) {
GC_delete_thread(pthread_self());
} else {
me -> flags |= FINISHED;
}
# if defined(THREAD_LOCAL_ALLOC)
/* It is required to call remove_specific defined in specific.c. */
GC_remove_specific(GC_thread_key);
# endif
}
GC_API int GC_CALL GC_unregister_my_thread(void)
{
pthread_t self = pthread_self();
GC_thread me;
IF_CANCEL(int cancel_state;)
DCL_LOCK_STATE;
LOCK();
DISABLE_CANCEL(cancel_state);
/* Wait for any GC that may be marking from our stack to */
/* complete before we remove this thread. */
GC_wait_for_gc_completion(FALSE);
me = GC_lookup_thread(self);
# ifdef DEBUG_THREADS
GC_log_printf(
"Called GC_unregister_my_thread on %p, gc_thread = %p\n",
(void *)self, me);
# endif
GC_ASSERT(me->id == self);
GC_unregister_my_thread_inner(me);
RESTORE_CANCEL(cancel_state);
UNLOCK();
return GC_SUCCESS;
}
/* Called at thread exit. */
/* Never called for main thread. That's OK, since it */
/* results in at most a tiny one-time leak. And */
/* linuxthreads doesn't reclaim the main threads */
/* resources or id anyway. */
GC_INNER_PTHRSTART void GC_thread_exit_proc(void *arg)
{
# ifdef DEBUG_THREADS
GC_log_printf("Called GC_thread_exit_proc on %p, gc_thread = %p\n",
(void *)((GC_thread)arg)->id, arg);
# endif
IF_CANCEL(int cancel_state;)
DCL_LOCK_STATE;
LOCK();
DISABLE_CANCEL(cancel_state);
GC_wait_for_gc_completion(FALSE);
GC_unregister_my_thread_inner((GC_thread)arg);
RESTORE_CANCEL(cancel_state);
UNLOCK();
}
GC_API int WRAP_FUNC(pthread_join)(pthread_t thread, void **retval)
{
int result;
GC_thread t;
DCL_LOCK_STATE;
INIT_REAL_SYMS();
LOCK();
t = GC_lookup_thread(thread);
/* This is guaranteed to be the intended one, since the thread id */
/* can't have been recycled by pthreads. */
UNLOCK();
result = REAL_FUNC(pthread_join)(thread, retval);
# if defined(GC_FREEBSD_THREADS)
/* On FreeBSD, the wrapped pthread_join() sometimes returns (what
appears to be) a spurious EINTR which caused the test and real code
to gratuitously fail. Having looked at system pthread library source
code, I see how this return code may be generated. In one path of
code, pthread_join() just returns the errno setting of the thread
being joined. This does not match the POSIX specification or the
local man pages thus I have taken the liberty to catch this one
spurious return value properly conditionalized on GC_FREEBSD_THREADS. */
if (result == EINTR) result = 0;
# endif
if (result == 0) {
LOCK();
/* Here the pthread thread id may have been recycled. */
GC_ASSERT((t -> flags & FINISHED) != 0);
GC_delete_gc_thread(t);
UNLOCK();
}
return result;
}
GC_API int WRAP_FUNC(pthread_detach)(pthread_t thread)
{
int result;
GC_thread t;
DCL_LOCK_STATE;
INIT_REAL_SYMS();
LOCK();
t = GC_lookup_thread(thread);
UNLOCK();
result = REAL_FUNC(pthread_detach)(thread);
if (result == 0) {
LOCK();
t -> flags |= DETACHED;
/* Here the pthread thread id may have been recycled. */
if ((t -> flags & FINISHED) != 0) {
GC_delete_gc_thread(t);
}
UNLOCK();
}
return result;
}
#ifndef GC_NO_PTHREAD_CANCEL
/* We should deal with the fact that apparently on Solaris and, */
/* probably, on some Linux we can't collect while a thread is */
/* exiting, since signals aren't handled properly. This currently */
/* gives rise to deadlocks. The only workaround seen is to intercept */
/* pthread_cancel() and pthread_exit(), and disable the collections */
/* until the thread exit handler is called. That's ugly, because we */
/* risk growing the heap unnecessarily. But it seems that we don't */
/* really have an option in that the process is not in a fully */
/* functional state while a thread is exiting. */
GC_API int WRAP_FUNC(pthread_cancel)(pthread_t thread)
{
# ifdef CANCEL_SAFE
GC_thread t;
DCL_LOCK_STATE;
# endif
INIT_REAL_SYMS();
# ifdef CANCEL_SAFE
LOCK();
t = GC_lookup_thread(thread);
/* We test DISABLED_GC because pthread_exit could be called at */
/* the same time. (If t is NULL then pthread_cancel should */
/* return ESRCH.) */
if (t != NULL && (t -> flags & DISABLED_GC) == 0) {
t -> flags |= DISABLED_GC;
GC_dont_gc++;
}
UNLOCK();
# endif
return REAL_FUNC(pthread_cancel)(thread);
}
#endif /* !GC_NO_PTHREAD_CANCEL */
#ifdef GC_PTHREAD_EXIT_ATTRIBUTE
GC_API GC_PTHREAD_EXIT_ATTRIBUTE void WRAP_FUNC(pthread_exit)(void *retval)
{
pthread_t self = pthread_self();
GC_thread me;
DCL_LOCK_STATE;
INIT_REAL_SYMS();
LOCK();
me = GC_lookup_thread(self);
/* We test DISABLED_GC because someone else could call */
/* pthread_cancel at the same time. */
if (me != 0 && (me -> flags & DISABLED_GC) == 0) {
me -> flags |= DISABLED_GC;
GC_dont_gc++;
}
UNLOCK();
# ifdef NACL
/* Native Client doesn't support pthread cleanup functions, */
/* so cleanup the thread here. */
GC_thread_exit_proc(0);
# endif
REAL_FUNC(pthread_exit)(retval);
}
#endif /* GC_PTHREAD_EXIT_ATTRIBUTE */
GC_INNER GC_bool GC_in_thread_creation = FALSE;
/* Protected by allocation lock. */
GC_INLINE void GC_record_stack_base(GC_thread me,
const struct GC_stack_base *sb)
{
# ifndef GC_DARWIN_THREADS
me -> stop_info.stack_ptr = sb -> mem_base;
# endif
me -> stack_end = sb -> mem_base;
if (me -> stack_end == NULL)
ABORT("Bad stack base in GC_register_my_thread");
# ifdef IA64
me -> backing_store_end = sb -> reg_base;
# endif
}
STATIC GC_thread GC_register_my_thread_inner(const struct GC_stack_base *sb,
pthread_t my_pthread)
{
GC_thread me;
GC_in_thread_creation = TRUE; /* OK to collect from unknown thread. */
me = GC_new_thread(my_pthread);
GC_in_thread_creation = FALSE;
if (me == 0)
ABORT("Failed to allocate memory for thread registering");
# ifdef GC_DARWIN_THREADS
me -> stop_info.mach_thread = mach_thread_self();
# endif
GC_record_stack_base(me, sb);
# ifdef GC_EXPLICIT_SIGNALS_UNBLOCK
/* Since this could be executed from a detached thread */
/* destructor, our signals might already be blocked. */
GC_unblock_gc_signals();
# endif
return me;
}
GC_API void GC_CALL GC_allow_register_threads(void)
{
/* Check GC is initialized and the current thread is registered. */
GC_ASSERT(GC_lookup_thread(pthread_self()) != 0);
GC_need_to_lock = TRUE; /* We are multi-threaded now. */
}
GC_API int GC_CALL GC_register_my_thread(const struct GC_stack_base *sb)
{
pthread_t self = pthread_self();
GC_thread me;
DCL_LOCK_STATE;
if (GC_need_to_lock == FALSE)
ABORT("Threads explicit registering is not previously enabled");
LOCK();
me = GC_lookup_thread(self);
if (0 == me) {
me = GC_register_my_thread_inner(sb, self);
me -> flags |= DETACHED;
/* Treat as detached, since we do not need to worry about */
/* pointer results. */
# if defined(THREAD_LOCAL_ALLOC)
GC_init_thread_local(&(me->tlfs));
# endif
UNLOCK();
return GC_SUCCESS;
} else if ((me -> flags & FINISHED) != 0) {
/* This code is executed when a thread is registered from the */
/* client thread key destructor. */
GC_record_stack_base(me, sb);
me -> flags &= ~FINISHED; /* but not DETACHED */
# ifdef GC_EXPLICIT_SIGNALS_UNBLOCK
/* Since this could be executed from a thread destructor, */
/* our signals might be blocked. */
GC_unblock_gc_signals();
# endif
# if defined(THREAD_LOCAL_ALLOC)
GC_init_thread_local(&(me->tlfs));
# endif
UNLOCK();
return GC_SUCCESS;
} else {
UNLOCK();
return GC_DUPLICATE;
}
}
struct start_info {
void *(*start_routine)(void *);
void *arg;
word flags;
sem_t registered; /* 1 ==> in our thread table, but */
/* parent hasn't yet noticed. */
};
/* Called from GC_inner_start_routine(). Defined in this file to */
/* minimize the number of include files in pthread_start.c (because */
/* sem_t and sem_post() are not used that file directly). */
GC_INNER_PTHRSTART GC_thread GC_start_rtn_prepare_thread(
void *(**pstart)(void *),
void **pstart_arg,
struct GC_stack_base *sb, void *arg)
{
struct start_info * si = arg;
pthread_t self = pthread_self();
GC_thread me;
DCL_LOCK_STATE;
# ifdef DEBUG_THREADS
GC_log_printf("Starting thread %p, pid = %ld, sp = %p\n",
(void *)self, (long)getpid(), &arg);
# endif
LOCK();
me = GC_register_my_thread_inner(sb, self);
me -> flags = si -> flags;
# if defined(THREAD_LOCAL_ALLOC)
GC_init_thread_local(&(me->tlfs));
# endif
UNLOCK();
*pstart = si -> start_routine;
# ifdef DEBUG_THREADS
GC_log_printf("start_routine = %p\n", (void *)(signed_word)(*pstart));
# endif
*pstart_arg = si -> arg;
sem_post(&(si -> registered)); /* Last action on si. */
/* OK to deallocate. */
return me;
}
GC_INNER_PTHRSTART void * GC_CALLBACK GC_inner_start_routine(
struct GC_stack_base *sb, void *arg);
/* defined in pthread_start.c */
STATIC void * GC_start_routine(void * arg)
{
# ifdef INCLUDE_LINUX_THREAD_DESCR
struct GC_stack_base sb;
# ifdef REDIRECT_MALLOC
/* GC_get_stack_base may call pthread_getattr_np, which can */
/* unfortunately call realloc, which may allocate from an */
/* unregistered thread. This is unpleasant, since it might */
/* force heap growth (or, even, heap overflow). */
GC_disable();
# endif
if (GC_get_stack_base(&sb) != GC_SUCCESS)
ABORT("Failed to get thread stack base");
# ifdef REDIRECT_MALLOC
GC_enable();
# endif
return GC_inner_start_routine(&sb, arg);
# else
return GC_call_with_stack_base(GC_inner_start_routine, arg);
# endif
}
GC_API int WRAP_FUNC(pthread_create)(pthread_t *new_thread,
GC_PTHREAD_CREATE_CONST pthread_attr_t *attr,
void *(*start_routine)(void *), void *arg)
{
int result;
int detachstate;
word my_flags = 0;
struct start_info * si;
DCL_LOCK_STATE;
/* This is otherwise saved only in an area mmapped by the thread */
/* library, which isn't visible to the collector. */
/* We resist the temptation to muck with the stack size here, */
/* even if the default is unreasonably small. That's the client's */
/* responsibility. */
INIT_REAL_SYMS();
LOCK();
si = (struct start_info *)GC_INTERNAL_MALLOC(sizeof(struct start_info),
NORMAL);
UNLOCK();
if (!EXPECT(parallel_initialized, TRUE))
GC_init_parallel();
if (EXPECT(0 == si, FALSE) &&
(si = (struct start_info *)
(*GC_get_oom_fn())(sizeof(struct start_info))) == 0)
return(ENOMEM);
if (sem_init(&(si -> registered), GC_SEM_INIT_PSHARED, 0) != 0)
ABORT("sem_init failed");
si -> start_routine = start_routine;
si -> arg = arg;
LOCK();
if (!EXPECT(GC_thr_initialized, TRUE))
GC_thr_init();
# ifdef GC_ASSERTIONS
{
size_t stack_size = 0;
if (NULL != attr) {
pthread_attr_getstacksize(attr, &stack_size);
}
if (0 == stack_size) {
pthread_attr_t my_attr;
pthread_attr_init(&my_attr);
pthread_attr_getstacksize(&my_attr, &stack_size);
pthread_attr_destroy(&my_attr);
}
/* On Solaris 10, with default attr initialization, */
/* stack_size remains 0. Fudge it. */
if (0 == stack_size) {
# ifndef SOLARIS
WARN("Failed to get stack size for assertion checking\n", 0);
# endif
stack_size = 1000000;
}
# ifdef PARALLEL_MARK
GC_ASSERT(stack_size >= (8*HBLKSIZE*sizeof(word)));
# else
/* FreeBSD-5.3/Alpha: default pthread stack is 64K, */
/* HBLKSIZE=8192, sizeof(word)=8 */
GC_ASSERT(stack_size >= 65536);
# endif
/* Our threads may need to do some work for the GC. */
/* Ridiculously small threads won't work, and they */
/* probably wouldn't work anyway. */
}
# endif
if (NULL == attr) {
detachstate = PTHREAD_CREATE_JOINABLE;
} else {
pthread_attr_getdetachstate(attr, &detachstate);
}
if (PTHREAD_CREATE_DETACHED == detachstate) my_flags |= DETACHED;
si -> flags = my_flags;
UNLOCK();
# ifdef DEBUG_THREADS
GC_log_printf("About to start new thread from thread %p\n",
(void *)pthread_self());
# endif
GC_need_to_lock = TRUE;
result = REAL_FUNC(pthread_create)(new_thread, attr, GC_start_routine, si);
/* Wait until child has been added to the thread table. */
/* This also ensures that we hold onto si until the child is done */
/* with it. Thus it doesn't matter whether it is otherwise */
/* visible to the collector. */
if (0 == result) {
IF_CANCEL(int cancel_state;)
# ifdef DEBUG_THREADS
if (new_thread)
GC_log_printf("Started thread %p\n", (void *)(*new_thread));
# endif
DISABLE_CANCEL(cancel_state);
/* pthread_create is not a cancellation point. */
while (0 != sem_wait(&(si -> registered))) {
if (EINTR != errno) ABORT("sem_wait failed");
}
RESTORE_CANCEL(cancel_state);
}
sem_destroy(&(si -> registered));
LOCK();
GC_INTERNAL_FREE(si);
UNLOCK();
return(result);
}
#if defined(USE_SPIN_LOCK) || !defined(NO_PTHREAD_TRYLOCK)
/* Spend a few cycles in a way that can't introduce contention with */
/* other threads. */
STATIC void GC_pause(void)
{
int i;
# if !defined(__GNUC__) || defined(__INTEL_COMPILER)
volatile word dummy = 0;
# endif
for (i = 0; i < 10; ++i) {
# if defined(__GNUC__) && !defined(__INTEL_COMPILER)
__asm__ __volatile__ (" " : : : "memory");
# else
/* Something that's unlikely to be optimized away. */
GC_noop1(++dummy);
# endif
}
}
#endif
#define SPIN_MAX 128 /* Maximum number of calls to GC_pause before */
/* give up. */
GC_INNER volatile GC_bool GC_collecting = 0;
/* A hint that we're in the collector and */
/* holding the allocation lock for an */
/* extended period. */
#if (!defined(USE_SPIN_LOCK) && !defined(NO_PTHREAD_TRYLOCK)) \
|| defined(PARALLEL_MARK)
/* If we don't want to use the below spinlock implementation, either */
/* because we don't have a GC_test_and_set implementation, or because */
/* we don't want to risk sleeping, we can still try spinning on */
/* pthread_mutex_trylock for a while. This appears to be very */
/* beneficial in many cases. */
/* I suspect that under high contention this is nearly always better */
/* than the spin lock. But it's a bit slower on a uniprocessor. */
/* Hence we still default to the spin lock. */
/* This is also used to acquire the mark lock for the parallel */
/* marker. */
/* Here we use a strict exponential backoff scheme. I don't know */
/* whether that's better or worse than the above. We eventually */
/* yield by calling pthread_mutex_lock(); it never makes sense to */
/* explicitly sleep. */
/* #define LOCK_STATS */
/* Note that LOCK_STATS requires AO_HAVE_test_and_set. */
#ifdef LOCK_STATS
volatile AO_t GC_spin_count = 0;
volatile AO_t GC_block_count = 0;
volatile AO_t GC_unlocked_count = 0;
#endif
STATIC void GC_generic_lock(pthread_mutex_t * lock)
{
#ifndef NO_PTHREAD_TRYLOCK
unsigned pause_length = 1;
unsigned i;
if (0 == pthread_mutex_trylock(lock)) {
# ifdef LOCK_STATS
(void)AO_fetch_and_add1(&GC_unlocked_count);
# endif
return;
}
for (; pause_length <= SPIN_MAX; pause_length <<= 1) {
for (i = 0; i < pause_length; ++i) {
GC_pause();
}
switch(pthread_mutex_trylock(lock)) {
case 0:
# ifdef LOCK_STATS
(void)AO_fetch_and_add1(&GC_spin_count);
# endif
return;
case EBUSY:
break;
default:
ABORT("Unexpected error from pthread_mutex_trylock");
}
}
#endif /* !NO_PTHREAD_TRYLOCK */
# ifdef LOCK_STATS
(void)AO_fetch_and_add1(&GC_block_count);
# endif
pthread_mutex_lock(lock);
}
#endif /* !USE_SPIN_LOCK || ... */
#if defined(USE_SPIN_LOCK)
/* Reasonably fast spin locks. Basically the same implementation */
/* as STL alloc.h. This isn't really the right way to do this. */
/* but until the POSIX scheduling mess gets straightened out ... */
GC_INNER volatile AO_TS_t GC_allocate_lock = AO_TS_INITIALIZER;
GC_INNER void GC_lock(void)
{
# define low_spin_max 30 /* spin cycles if we suspect uniprocessor */
# define high_spin_max SPIN_MAX /* spin cycles for multiprocessor */
static unsigned spin_max = low_spin_max;
unsigned my_spin_max;
static unsigned last_spins = 0;
unsigned my_last_spins;
unsigned i;
if (AO_test_and_set_acquire(&GC_allocate_lock) == AO_TS_CLEAR) {
return;
}
my_spin_max = spin_max;
my_last_spins = last_spins;
for (i = 0; i < my_spin_max; i++) {
if (GC_collecting || GC_nprocs == 1) goto yield;
if (i < my_last_spins/2) {
GC_pause();
continue;
}
if (AO_test_and_set_acquire(&GC_allocate_lock) == AO_TS_CLEAR) {
/*
* got it!
* Spinning worked. Thus we're probably not being scheduled
* against the other process with which we were contending.
* Thus it makes sense to spin longer the next time.
*/
last_spins = i;
spin_max = high_spin_max;
return;
}
}
/* We are probably being scheduled against the other process. Sleep. */
spin_max = low_spin_max;
yield:
for (i = 0;; ++i) {
if (AO_test_and_set_acquire(&GC_allocate_lock) == AO_TS_CLEAR) {
return;
}
# define SLEEP_THRESHOLD 12
/* Under Linux very short sleeps tend to wait until */
/* the current time quantum expires. On old Linux */
/* kernels nanosleep(<= 2ms) just spins under Linux. */
/* (Under 2.4, this happens only for real-time */
/* processes.) We want to minimize both behaviors */
/* here. */
if (i < SLEEP_THRESHOLD) {
sched_yield();
} else {
struct timespec ts;
if (i > 24) i = 24;
/* Don't wait for more than about 15msecs, even */
/* under extreme contention. */
ts.tv_sec = 0;
ts.tv_nsec = 1 << i;
nanosleep(&ts, 0);
}
}
}
#else /* !USE_SPIN_LOCK */
GC_INNER void GC_lock(void)
{
#ifndef NO_PTHREAD_TRYLOCK
if (1 == GC_nprocs || GC_collecting) {
pthread_mutex_lock(&GC_allocate_ml);
} else {
GC_generic_lock(&GC_allocate_ml);
}
#else /* !NO_PTHREAD_TRYLOCK */
pthread_mutex_lock(&GC_allocate_ml);
#endif /* !NO_PTHREAD_TRYLOCK */
}
#endif /* !USE_SPIN_LOCK */
#ifdef PARALLEL_MARK
# ifdef GC_ASSERTIONS
STATIC unsigned long GC_mark_lock_holder = NO_THREAD;
# define SET_MARK_LOCK_HOLDER \
(void)(GC_mark_lock_holder = NUMERIC_THREAD_ID(pthread_self()))
# define UNSET_MARK_LOCK_HOLDER \
do { \
GC_ASSERT(GC_mark_lock_holder \
== NUMERIC_THREAD_ID(pthread_self())); \
GC_mark_lock_holder = NO_THREAD; \
} while (0)
# else
# define SET_MARK_LOCK_HOLDER (void)0
# define UNSET_MARK_LOCK_HOLDER (void)0
# endif /* !GC_ASSERTIONS */
#ifdef GLIBC_2_1_MUTEX_HACK
/* Ugly workaround for a linux threads bug in the final versions */
/* of glibc2.1. Pthread_mutex_trylock sets the mutex owner */
/* field even when it fails to acquire the mutex. This causes */
/* pthread_cond_wait to die. Remove for glibc2.2. */
/* According to the man page, we should use */
/* PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP, but that isn't actually */
/* defined. */
static pthread_mutex_t mark_mutex =
{0, 0, 0, PTHREAD_MUTEX_ERRORCHECK_NP, {0, 0}};
#else
static pthread_mutex_t mark_mutex = PTHREAD_MUTEX_INITIALIZER;
#endif
static pthread_cond_t builder_cv = PTHREAD_COND_INITIALIZER;
GC_INNER void GC_acquire_mark_lock(void)
{
GC_ASSERT(GC_mark_lock_holder != NUMERIC_THREAD_ID(pthread_self()));
GC_generic_lock(&mark_mutex);
SET_MARK_LOCK_HOLDER;
}
GC_INNER void GC_release_mark_lock(void)
{
UNSET_MARK_LOCK_HOLDER;
if (pthread_mutex_unlock(&mark_mutex) != 0) {
ABORT("pthread_mutex_unlock failed");
}
}
/* Collector must wait for a freelist builders for 2 reasons: */
/* 1) Mark bits may still be getting examined without lock. */
/* 2) Partial free lists referenced only by locals may not be scanned */
/* correctly, e.g. if they contain "pointer-free" objects, since the */
/* free-list link may be ignored. */
STATIC void GC_wait_builder(void)
{
ASSERT_CANCEL_DISABLED();
UNSET_MARK_LOCK_HOLDER;
if (pthread_cond_wait(&builder_cv, &mark_mutex) != 0) {
ABORT("pthread_cond_wait failed");
}
GC_ASSERT(GC_mark_lock_holder == NO_THREAD);
SET_MARK_LOCK_HOLDER;
}
GC_INNER void GC_wait_for_reclaim(void)
{
GC_acquire_mark_lock();
while (GC_fl_builder_count > 0) {
GC_wait_builder();
}
GC_release_mark_lock();
}
GC_INNER void GC_notify_all_builder(void)
{
GC_ASSERT(GC_mark_lock_holder == NUMERIC_THREAD_ID(pthread_self()));
if (pthread_cond_broadcast(&builder_cv) != 0) {
ABORT("pthread_cond_broadcast failed");
}
}
static pthread_cond_t mark_cv = PTHREAD_COND_INITIALIZER;
GC_INNER void GC_wait_marker(void)
{
ASSERT_CANCEL_DISABLED();
UNSET_MARK_LOCK_HOLDER;
if (pthread_cond_wait(&mark_cv, &mark_mutex) != 0) {
ABORT("pthread_cond_wait failed");
}
GC_ASSERT(GC_mark_lock_holder == NO_THREAD);
SET_MARK_LOCK_HOLDER;
}
GC_INNER void GC_notify_all_marker(void)
{
if (pthread_cond_broadcast(&mark_cv) != 0) {
ABORT("pthread_cond_broadcast failed");
}
}
#endif /* PARALLEL_MARK */
#ifdef PTHREAD_REGISTER_CANCEL_WEAK_STUBS
/* Workaround "undefined reference" linkage errors on some targets. */
void __pthread_register_cancel() __attribute__((__weak__));
void __pthread_unregister_cancel() __attribute__((__weak__));
void __pthread_register_cancel() {}
void __pthread_unregister_cancel() {}
#endif
#endif /* GC_PTHREADS */