#include <signal.h>
#include <stddef.h>
#include <errno.h>
-#include "runtime.h"
+#include <sys/types.h>
+#include <sys/wait.h>
+
#include "sbcl.h"
-#include "validate.h" /* for CONTROL_STACK_SIZE etc */
+#include "runtime.h"
+#include "validate.h" /* for CONTROL_STACK_SIZE etc */
+#include "alloc.h"
#include "thread.h"
#include "arch.h"
#include "target-arch-os.h"
#include "globals.h"
#include "dynbind.h"
#include "genesis/cons.h"
+#include "genesis/fdefn.h"
+#include "interr.h" /* for lose() */
+#include "gc-internal.h"
+
#define ALIEN_STACK_SIZE (1*1024*1024) /* 1Mb size chosen at random */
-int dynamic_values_bytes=4096*sizeof(lispobj); /* same for all threads */
-struct thread *all_threads;
-volatile lispobj all_threads_lock;
+struct freeable_stack {
+ os_thread_t os_thread;
+ os_vm_address_t stack;
+};
+
+static struct freeable_stack * volatile freeable_stack = 0;
+
+int dynamic_values_bytes=4096*sizeof(lispobj); /* same for all threads */
+struct thread * volatile all_threads;
extern struct interrupt_data * global_interrupt_data;
+extern int linux_no_threads_p;
-void get_spinlock(lispobj *word,int value);
+#ifdef LISP_FEATURE_SB_THREAD
+pthread_mutex_t all_threads_lock = PTHREAD_MUTEX_INITIALIZER;
+#endif
-int
+#if defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64)
+extern lispobj call_into_lisp_first_time(lispobj fun, lispobj *args, int nargs);
+#endif
+
+static void
+link_thread(struct thread *th)
+{
+ if (all_threads) all_threads->prev=th;
+ th->next=all_threads;
+ th->prev=0;
+ all_threads=th;
+}
+
+#ifdef LISP_FEATURE_SB_THREAD
+static void
+unlink_thread(struct thread *th)
+{
+ if (th->prev)
+ th->prev->next = th->next;
+ else
+ all_threads = th->next;
+ if (th->next)
+ th->next->prev = th->prev;
+}
+#endif
+
+static int
initial_thread_trampoline(struct thread *th)
{
lispobj function;
+#if defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64)
lispobj *args = NULL;
- function = th->unbound_marker;
- th->unbound_marker = UNBOUND_MARKER_WIDETAG;
+#endif
+ function = th->no_tls_value_marker;
+ th->no_tls_value_marker = NO_TLS_VALUE_MARKER_WIDETAG;
if(arch_os_thread_init(th)==0) return 1;
+ link_thread(th);
+ th->os_thread=thread_self();
+ protect_control_stack_guard_page(1);
- if(th->pid < 1) lose("th->pid not set up right");
- th->state=STATE_RUNNING;
-#if defined(LISP_FEATURE_X86)
+#if defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64)
return call_into_lisp_first_time(function,args,0);
#else
return funcall0(function);
#endif
}
-/* this is the first thing that clone() runs in the child (which is
- * why the silly calling convention). Basically it calls the user's
- * requested lisp function after doing arch_os_thread_init and
- * whatever other bookkeeping needs to be done
- */
+#define THREAD_STRUCT_SIZE (THREAD_CONTROL_STACK_SIZE + BINDING_STACK_SIZE + \
+ ALIEN_STACK_SIZE + dynamic_values_bytes + \
+ 32 * SIGSTKSZ)
#ifdef LISP_FEATURE_SB_THREAD
+
+static void
+free_thread_stack_later(struct thread *thread_to_be_cleaned_up)
+{
+ struct freeable_stack *new_freeable_stack = 0;
+ if (thread_to_be_cleaned_up) {
+ new_freeable_stack = (struct freeable_stack *)
+ os_validate(0, sizeof(struct freeable_stack));
+ new_freeable_stack->os_thread = thread_to_be_cleaned_up->os_thread;
+ new_freeable_stack->stack = (os_vm_address_t)
+ thread_to_be_cleaned_up->control_stack_start;
+ }
+ new_freeable_stack = (struct freeable_stack *)
+ swap_lispobjs((lispobj *)(void *)&freeable_stack,
+ (lispobj)new_freeable_stack);
+ if (new_freeable_stack) {
+ FSHOW((stderr,"/reaping %lu\n", new_freeable_stack->os_thread));
+ /* Under NPTL pthread_join really waits until the thread
+ * exists and the stack can be safely freed. This is sadly not
+ * mandated by the pthread spec. */
+ gc_assert(pthread_join(new_freeable_stack->os_thread, NULL) == 0);
+ os_invalidate(new_freeable_stack->stack, THREAD_STRUCT_SIZE);
+ os_invalidate((os_vm_address_t) new_freeable_stack,
+ sizeof(struct freeable_stack));
+ }
+}
+
+/* this is the first thing that runs in the child (which is why the
+ * silly calling convention). Basically it calls the user's requested
+ * lisp function after doing arch_os_thread_init and whatever other
+ * bookkeeping needs to be done
+ */
int
new_thread_trampoline(struct thread *th)
{
lispobj function;
- function = th->unbound_marker;
- th->unbound_marker = UNBOUND_MARKER_WIDETAG;
- if(arch_os_thread_init(th)==0) return 1;
-
- /* wait here until our thread is linked into all_threads: see below */
- while(th->pid<1) sched_yield();
+ int result;
+ FSHOW((stderr,"/creating thread %lu\n", thread_self()));
+ function = th->no_tls_value_marker;
+ th->no_tls_value_marker = NO_TLS_VALUE_MARKER_WIDETAG;
+ if(arch_os_thread_init(th)==0) {
+ /* FIXME: handle error */
+ lose("arch_os_thread_init failed\n");
+ }
- th->state=STATE_RUNNING;
- return funcall0(function);
+ th->os_thread=thread_self();
+ protect_control_stack_guard_page(1);
+ /* Since GC can only know about this thread from the all_threads
+ * list and we're just adding this thread to it there is no danger
+ * of deadlocking even with SIG_STOP_FOR_GC blocked (which it is
+ * not). */
+ pthread_mutex_lock(&all_threads_lock);
+ link_thread(th);
+ pthread_mutex_unlock(&all_threads_lock);
+
+ result = funcall0(function);
+ th->state=STATE_DEAD;
+
+ /* SIG_STOP_FOR_GC is blocked and GC might be waiting for this
+ * thread, but since we are already dead it won't wait long. */
+ pthread_mutex_lock(&all_threads_lock);
+ gc_alloc_update_page_tables(0, &th->alloc_region);
+ unlink_thread(th);
+ pthread_mutex_unlock(&all_threads_lock);
+
+ if(th->tls_cookie>=0) arch_os_thread_cleanup(th);
+ os_invalidate((os_vm_address_t)th->interrupt_data,
+ (sizeof (struct interrupt_data)));
+ free_thread_stack_later(th);
+ FSHOW((stderr,"/exiting thread %lu\n", thread_self()));
+ return result;
}
+
#endif /* LISP_FEATURE_SB_THREAD */
+static void
+free_thread_struct(struct thread *th)
+{
+ if (th->interrupt_data)
+ os_invalidate((os_vm_address_t) th->interrupt_data,
+ (sizeof (struct interrupt_data)));
+ os_invalidate((os_vm_address_t) th->control_stack_start,
+ THREAD_STRUCT_SIZE);
+}
+
/* this is called from any other thread to create the new one, and
- * initialize all parts of it that can be initialized from another
- * thread
+ * initialize all parts of it that can be initialized from another
+ * thread
*/
-struct thread * create_thread_struct(lispobj initial_function) {
+static struct thread *
+create_thread_struct(lispobj initial_function) {
union per_thread_data *per_thread;
- struct thread *th=0; /* subdue gcc */
+ struct thread *th=0; /* subdue gcc */
void *spaces=0;
+#ifdef LISP_FEATURE_SB_THREAD
+ int i;
+#endif
/* may as well allocate all the spaces at once: it saves us from
* having to decide what to do if only some of the allocations
* succeed */
- spaces=os_validate(0,
- THREAD_CONTROL_STACK_SIZE+
- BINDING_STACK_SIZE+
- ALIEN_STACK_SIZE+
- dynamic_values_bytes+
- 32*SIGSTKSZ
- );
- if(!spaces) goto cleanup;
+ spaces=os_validate(0, THREAD_STRUCT_SIZE);
+ if(!spaces)
+ return NULL;
per_thread=(union per_thread_data *)
- (spaces+
- THREAD_CONTROL_STACK_SIZE+
- BINDING_STACK_SIZE+
- ALIEN_STACK_SIZE);
+ (spaces+
+ THREAD_CONTROL_STACK_SIZE+
+ BINDING_STACK_SIZE+
+ ALIEN_STACK_SIZE);
- th=&per_thread->thread;
- if(all_threads) {
- memcpy(per_thread,arch_os_get_current_thread(),
- dynamic_values_bytes);
- } else {
#ifdef LISP_FEATURE_SB_THREAD
- int i;
- for(i=0;i<(dynamic_values_bytes/sizeof(lispobj));i++)
- per_thread->dynamic_values[i]=UNBOUND_MARKER_WIDETAG;
- if(SymbolValue(FREE_TLS_INDEX,0)==UNBOUND_MARKER_WIDETAG)
- SetSymbolValue
- (FREE_TLS_INDEX,
- make_fixnum(MAX_INTERRUPTS+
- sizeof(struct thread)/sizeof(lispobj)),
- 0);
+ for(i = 0; i < (dynamic_values_bytes / sizeof(lispobj)); i++)
+ per_thread->dynamic_values[i] = NO_TLS_VALUE_MARKER_WIDETAG;
+ if (all_threads == 0) {
+ if(SymbolValue(FREE_TLS_INDEX,0)==UNBOUND_MARKER_WIDETAG) {
+ SetSymbolValue
+ (FREE_TLS_INDEX,
+ /* FIXME: should be MAX_INTERRUPTS -1 ? */
+ make_fixnum(MAX_INTERRUPTS+
+ sizeof(struct thread)/sizeof(lispobj)),
+ 0);
+ SetSymbolValue(TLS_INDEX_LOCK,make_fixnum(0),0);
+ }
#define STATIC_TLS_INIT(sym,field) \
((struct symbol *)(sym-OTHER_POINTER_LOWTAG))->tls_index= \
make_fixnum(THREAD_SLOT_OFFSET_WORDS(field))
-
- STATIC_TLS_INIT(BINDING_STACK_START,binding_stack_start);
- STATIC_TLS_INIT(BINDING_STACK_POINTER,binding_stack_pointer);
- STATIC_TLS_INIT(CONTROL_STACK_START,control_stack_start);
- STATIC_TLS_INIT(CONTROL_STACK_END,control_stack_end);
- STATIC_TLS_INIT(ALIEN_STACK,alien_stack_pointer);
-#ifdef LISP_FEATURE_X86
- STATIC_TLS_INIT(PSEUDO_ATOMIC_ATOMIC,pseudo_atomic_atomic);
- STATIC_TLS_INIT(PSEUDO_ATOMIC_INTERRUPTED,pseudo_atomic_interrupted);
+
+ STATIC_TLS_INIT(BINDING_STACK_START,binding_stack_start);
+ STATIC_TLS_INIT(BINDING_STACK_POINTER,binding_stack_pointer);
+ STATIC_TLS_INIT(CONTROL_STACK_START,control_stack_start);
+ STATIC_TLS_INIT(CONTROL_STACK_END,control_stack_end);
+ STATIC_TLS_INIT(ALIEN_STACK,alien_stack_pointer);
+#if defined(LISP_FEATURE_X86) || defined (LISP_FEATURE_X86_64)
+ STATIC_TLS_INIT(PSEUDO_ATOMIC_ATOMIC,pseudo_atomic_atomic);
+ STATIC_TLS_INIT(PSEUDO_ATOMIC_INTERRUPTED,pseudo_atomic_interrupted);
#endif
#undef STATIC_TLS_INIT
-#endif
}
+#endif
+ th=&per_thread->thread;
th->control_stack_start = spaces;
th->binding_stack_start=
- (lispobj*)((void*)th->control_stack_start+THREAD_CONTROL_STACK_SIZE);
+ (lispobj*)((void*)th->control_stack_start+THREAD_CONTROL_STACK_SIZE);
th->control_stack_end = th->binding_stack_start;
th->alien_stack_start=
- (lispobj*)((void*)th->binding_stack_start+BINDING_STACK_SIZE);
+ (lispobj*)((void*)th->binding_stack_start+BINDING_STACK_SIZE);
th->binding_stack_pointer=th->binding_stack_start;
th->this=th;
- th->pid=0;
- th->state=STATE_STOPPED;
+ th->os_thread=0;
+ th->state=STATE_RUNNING;
#ifdef LISP_FEATURE_STACK_GROWS_DOWNWARD_NOT_UPWARD
th->alien_stack_pointer=((void *)th->alien_stack_start
- + ALIEN_STACK_SIZE-4); /* naked 4. FIXME */
+ + ALIEN_STACK_SIZE-N_WORD_BYTES);
#else
th->alien_stack_pointer=((void *)th->alien_stack_start);
#endif
-#ifdef LISP_FEATURE_X86
+#if defined(LISP_FEATURE_X86) || defined (LISP_FEATURE_X86_64)
th->pseudo_atomic_interrupted=0;
th->pseudo_atomic_atomic=0;
#endif
#ifndef LISP_FEATURE_SB_THREAD
/* the tls-points-into-struct-thread trick is only good for threaded
* sbcl, because unithread sbcl doesn't have tls. So, we copy the
- * appropriate values from struct thread here, and make sure that
+ * appropriate values from struct thread here, and make sure that
* we use the appropriate SymbolValue macros to access any of the
* variable quantities from the C runtime. It's not quite OAOOM,
* it just feels like it */
- SetSymbolValue(BINDING_STACK_START,th->binding_stack_start,th);
- SetSymbolValue(CONTROL_STACK_START,th->control_stack_start,th);
- SetSymbolValue(CONTROL_STACK_END,th->control_stack_end,th);
-#ifdef LISP_FEATURE_X86
- SetSymbolValue(BINDING_STACK_POINTER,th->binding_stack_pointer,th);
- SetSymbolValue(ALIEN_STACK,th->alien_stack_pointer,th);
- SetSymbolValue(PSEUDO_ATOMIC_ATOMIC,th->pseudo_atomic_atomic,th);
+ SetSymbolValue(BINDING_STACK_START,(lispobj)th->binding_stack_start,th);
+ SetSymbolValue(CONTROL_STACK_START,(lispobj)th->control_stack_start,th);
+ SetSymbolValue(CONTROL_STACK_END,(lispobj)th->control_stack_end,th);
+#if defined(LISP_FEATURE_X86) || defined (LISP_FEATURE_X86_64)
+ SetSymbolValue(BINDING_STACK_POINTER,(lispobj)th->binding_stack_pointer,th);
+ SetSymbolValue(ALIEN_STACK,(lispobj)th->alien_stack_pointer,th);
+ SetSymbolValue(PSEUDO_ATOMIC_ATOMIC,(lispobj)th->pseudo_atomic_atomic,th);
SetSymbolValue(PSEUDO_ATOMIC_INTERRUPTED,th->pseudo_atomic_interrupted,th);
#else
current_binding_stack_pointer=th->binding_stack_pointer;
current_control_stack_pointer=th->control_stack_start;
#endif
-#endif
+#endif
bind_variable(CURRENT_CATCH_BLOCK,make_fixnum(0),th);
- bind_variable(CURRENT_UNWIND_PROTECT_BLOCK,make_fixnum(0),th);
+ bind_variable(CURRENT_UNWIND_PROTECT_BLOCK,make_fixnum(0),th);
bind_variable(FREE_INTERRUPT_CONTEXT_INDEX,make_fixnum(0),th);
bind_variable(INTERRUPT_PENDING, NIL,th);
bind_variable(INTERRUPTS_ENABLED,T,th);
+ bind_variable(GC_PENDING,NIL,th);
+#ifdef LISP_FEATURE_SB_THREAD
+ bind_variable(STOP_FOR_GC_PENDING,NIL,th);
+#endif
- th->interrupt_data=os_validate(0,(sizeof (struct interrupt_data)));
- if(all_threads)
- memcpy(th->interrupt_data,
- arch_os_get_current_thread()->interrupt_data,
- sizeof (struct interrupt_data));
- else
- memcpy(th->interrupt_data,global_interrupt_data,
- sizeof (struct interrupt_data));
-
- th->unbound_marker=initial_function;
+ th->interrupt_data = (struct interrupt_data *)
+ os_validate(0,(sizeof (struct interrupt_data)));
+ if (!th->interrupt_data) {
+ free_thread_struct(th);
+ return 0;
+ }
+ th->interrupt_data->pending_handler = 0;
+ th->no_tls_value_marker=initial_function;
return th;
- cleanup:
- /* if(th && th->tls_cookie>=0) os_free_tls_pointer(th); */
- if(spaces) os_invalidate(spaces,
- THREAD_CONTROL_STACK_SIZE+BINDING_STACK_SIZE+
- ALIEN_STACK_SIZE+dynamic_values_bytes);
- return 0;
-}
-
-void link_thread(struct thread *th,pid_t kid_pid)
-{
- get_spinlock(&all_threads_lock,kid_pid);
- th->next=all_threads;
- all_threads=th;
- /* note that th->pid is 0 at this time. We rely on all_threads_lock
- * to ensure that we don't have >1 thread with pid=0 on the list at once
- */
- protect_control_stack_guard_page(th->pid,1);
- release_spinlock(&all_threads_lock);
- th->pid=kid_pid; /* child will not start until this is set */
}
void create_initial_thread(lispobj initial_function) {
struct thread *th=create_thread_struct(initial_function);
- pid_t kid_pid=getpid();
- if(th && kid_pid>0) {
- link_thread(th,kid_pid);
- initial_thread_trampoline(all_threads); /* no return */
- } else lose("can't create initial thread");
+ if(th) {
+ initial_thread_trampoline(th); /* no return */
+ } else lose("can't create initial thread\n");
}
#ifdef LISP_FEATURE_SB_THREAD
-pid_t create_thread(lispobj initial_function) {
- struct thread *th=create_thread_struct(initial_function);
- pid_t kid_pid=clone(new_thread_trampoline,
- (((void*)th->control_stack_start)+
- THREAD_CONTROL_STACK_SIZE-4),
- CLONE_FILES|SIG_THREAD_EXIT|CLONE_VM,th);
-
- if(th && kid_pid>0) {
- link_thread(th,kid_pid);
- return th->pid;
- } else {
- destroy_thread(th);
- return 0;
- }
-}
+
+#ifndef __USE_XOPEN2K
+extern int pthread_attr_setstack (pthread_attr_t *__attr, void *__stackaddr,
+ size_t __stacksize);
#endif
-void destroy_thread (struct thread *th)
+boolean create_os_thread(struct thread *th,os_thread_t *kid_tid)
{
- /* precondition: the unix task has already been killed and exited.
- * This is called by the parent */
-#ifdef LISP_FEATURE_GENCGC
- gc_alloc_update_page_tables(0, &th->alloc_region);
-#endif
- get_spinlock(&all_threads_lock,th->pid);
- th->state=STATE_STOPPED;
- if(th==all_threads)
- all_threads=th->next;
- else {
- struct thread *th1=all_threads;
- while(th1 && th1->next!=th) th1=th1->next;
- if(th1) th1->next=th->next; /* unlink */
- }
- release_spinlock(&all_threads_lock);
- if(th && th->tls_cookie>=0) arch_os_thread_cleanup(th);
- os_invalidate((os_vm_address_t) th->control_stack_start,
- ((sizeof (lispobj))
- * (th->control_stack_end-th->control_stack_start)) +
- BINDING_STACK_SIZE+ALIEN_STACK_SIZE+dynamic_values_bytes+
- 32*SIGSTKSZ);
+ /* The new thread inherits the restrictive signal mask set here,
+ * and enables signals again when it is set up properly. */
+ pthread_attr_t attr;
+ sigset_t newset,oldset;
+ boolean r=1;
+ sigemptyset(&newset);
+ /* Blocking deferrable signals is enough, no need to block
+ * SIG_STOP_FOR_GC because the child process is not linked onto
+ * all_threads until it's ready. */
+ sigaddset_deferrable(&newset);
+ thread_sigmask(SIG_BLOCK, &newset, &oldset);
+
+ if((pthread_attr_init(&attr)) ||
+ (pthread_attr_setstack(&attr,th->control_stack_start,
+ THREAD_CONTROL_STACK_SIZE-16)) ||
+ (pthread_create
+ (kid_tid,&attr,(void *(*)(void *))new_thread_trampoline,th)))
+ r=0;
+ thread_sigmask(SIG_SETMASK,&oldset,0);
+ return r;
}
-
-struct thread *find_thread_by_pid(pid_t pid)
-{
+os_thread_t create_thread(lispobj initial_function) {
struct thread *th;
- for_each_thread(th)
- if(th->pid==pid) return th;
- return 0;
-}
+ os_thread_t kid_tid;
-/* These are not needed unless #+SB-THREAD, and since sigwaitinfo()
- * doesn't seem to be easily available everywhere (OpenBSD...) it's
- * more trouble than it's worth to compile it when not needed. */
-#if defined LISP_FEATURE_SB_THREAD
-void block_sigcont(void)
-{
- /* don't allow ourselves to receive SIGCONT while we're in the
- * "ambiguous" state of being on the queue but not actually stopped.
- */
- sigset_t newset;
- sigemptyset(&newset);
- sigaddset(&newset,SIG_DEQUEUE);
- sigprocmask(SIG_BLOCK, &newset, 0);
-}
+ if(linux_no_threads_p) return 0;
-void unblock_sigcont_and_sleep(void)
-{
- sigset_t set;
- sigemptyset(&set);
- sigaddset(&set,SIG_DEQUEUE);
- do {
- errno=0;
- sigwaitinfo(&set,0);
- }while(errno==EINTR);
- sigprocmask(SIG_UNBLOCK,&set,0);
+ /* Assuming that a fresh thread struct has no lisp objects in it,
+ * linking it to all_threads can be left to the thread itself
+ * without fear of gc lossage. initial_function violates this
+ * assumption and must stay pinned until the child starts up. */
+ th = create_thread_struct(initial_function);
+ if(th==0) return 0;
+
+ if (create_os_thread(th,&kid_tid)) {
+ return kid_tid;
+ } else {
+ free_thread_struct(th);
+ return 0;
+ }
}
-int interrupt_thread(pid_t pid, lispobj function)
+/* Send the signo to os_thread, retry if the rt signal queue is
+ * full. */
+static int kill_thread_safely(os_thread_t os_thread, int signo)
{
- union sigval sigval;
- sigval.sival_int=function;
-
- return sigqueue(pid, SIG_INTERRUPT_THREAD, sigval);
+ int r;
+ /* The man page does not mention EAGAIN as a valid return value
+ * for either pthread_kill or kill. But that's theory, this is
+ * practice. By waiting here we assume that the delivery of this
+ * signal is not necessary for the delivery of the signals in the
+ * queue. In other words, we _assume_ there are no deadlocks. */
+ while ((r=pthread_kill(os_thread,signo))==EAGAIN) {
+ /* wait a bit then try again in the hope of the rt signal
+ * queue not being full */
+ FSHOW_SIGNAL((stderr,"/rt signal queue full\n"));
+ /* FIXME: some kind of backoff (random, exponential) would be
+ * nice. */
+ sleep(1);
+ }
+ return r;
}
-int signal_thread_to_dequeue (pid_t pid)
+int signal_interrupt_thread(os_thread_t os_thread)
{
- return kill (pid, SIG_DEQUEUE);
+ int status = kill_thread_safely(os_thread, SIG_INTERRUPT_THREAD);
+ if (status == 0) {
+ return 0;
+ } else if (status == ESRCH) {
+ return -1;
+ } else {
+ lose("cannot send SIG_INTERRUPT_THREAD to thread=%lu: %d, %s\n",
+ os_thread, status, strerror(status));
+ }
}
-
-/* stopping the world is a two-stage process. From this thread we signal
- * all the others with SIG_STOP_FOR_GC. The handler for this thread does
- * the usual pseudo-atomic checks (we don't want to stop a thread while
- * it's in the middle of allocation) then kills _itself_ with SIGSTOP.
+/* stopping the world is a two-stage process. From this thread we signal
+ * all the others with SIG_STOP_FOR_GC. The handler for this signal does
+ * the usual pseudo-atomic checks (we don't want to stop a thread while
+ * it's in the middle of allocation) then waits for another SIG_STOP_FOR_GC.
*/
+/* To avoid deadlocks when gc stops the world all clients of each
+ * mutex must enable or disable SIG_STOP_FOR_GC for the duration of
+ * holding the lock, but they must agree on which. */
void gc_stop_the_world()
{
- /* stop all other threads by sending them SIG_STOP_FOR_GC */
struct thread *p,*th=arch_os_get_current_thread();
- pid_t old_pid;
- int finished=0;
- do {
- get_spinlock(&all_threads_lock,th->pid);
- for(p=all_threads,old_pid=p->pid; p; p=p->next) {
- if(p==th) continue;
- if(p->state!=STATE_RUNNING) continue;
- p->state=STATE_STOPPING;
- kill(p->pid,SIG_STOP_FOR_GC);
- }
- release_spinlock(&all_threads_lock);
- sched_yield();
- /* if everything has stopped, and there is no possibility that
- * a new thread has been created, we're done. Otherwise go
- * round again and signal anything that sprang up since last
- * time */
- if(old_pid==all_threads->pid) {
- finished=1;
- for_each_thread(p)
- finished = finished &&
- ((p==th) || (p->state==STATE_STOPPED));
- }
- } while(!finished);
+ int status;
+ FSHOW_SIGNAL((stderr,"/gc_stop_the_world:waiting on lock, thread=%lu\n",
+ th->os_thread));
+ /* keep threads from starting while the world is stopped. */
+ pthread_mutex_lock(&all_threads_lock); \
+ FSHOW_SIGNAL((stderr,"/gc_stop_the_world:got lock, thread=%lu\n",
+ th->os_thread));
+ /* stop all other threads by sending them SIG_STOP_FOR_GC */
+ for(p=all_threads; p; p=p->next) {
+ gc_assert(p->os_thread != 0);
+ if((p!=th) && ((p->state==STATE_RUNNING))) {
+ FSHOW_SIGNAL((stderr,"/gc_stop_the_world: suspending %lu\n",
+ p->os_thread));
+ status=kill_thread_safely(p->os_thread,SIG_STOP_FOR_GC);
+ if (status==ESRCH) {
+ /* This thread has exited. */
+ gc_assert(p->state==STATE_DEAD);
+ } else if (status) {
+ lose("cannot send suspend thread=%lu: %d, %s\n",
+ p->os_thread,status,strerror(status));
+ }
+ }
+ }
+ FSHOW_SIGNAL((stderr,"/gc_stop_the_world:signals sent\n"));
+ /* wait for the running threads to stop or finish */
+ for(p=all_threads;p;) {
+ if((p!=th) && (p->state==STATE_RUNNING)) {
+ sched_yield();
+ } else {
+ p=p->next;
+ }
+ }
+ FSHOW_SIGNAL((stderr,"/gc_stop_the_world:end\n"));
}
void gc_start_the_world()
{
struct thread *p,*th=arch_os_get_current_thread();
- get_spinlock(&all_threads_lock,th->pid);
+ int status;
+ /* if a resumed thread creates a new thread before we're done with
+ * this loop, the new thread will get consed on the front of
+ * all_threads, but it won't have been stopped so won't need
+ * restarting */
+ FSHOW_SIGNAL((stderr,"/gc_start_the_world:begin\n"));
for(p=all_threads;p;p=p->next) {
- if(p==th) continue;
- p->state=STATE_RUNNING;
- kill(p->pid,SIG_STOP_FOR_GC);
+ gc_assert(p->os_thread!=0);
+ if((p!=th) && (p->state!=STATE_DEAD)) {
+ if(p->state!=STATE_SUSPENDED) {
+ lose("gc_start_the_world: wrong thread state is %d\n",
+ fixnum_value(p->state));
+ }
+ FSHOW_SIGNAL((stderr, "/gc_start_the_world: resuming %lu\n",
+ p->os_thread));
+ p->state=STATE_RUNNING;
+ status=kill_thread_safely(p->os_thread,SIG_STOP_FOR_GC);
+ if (status) {
+ lose("cannot resume thread=%lu: %d, %s\n",
+ p->os_thread,status,strerror(status));
+ }
+ }
}
- release_spinlock(&all_threads_lock);
+ /* If we waited here until all threads leave STATE_SUSPENDED, then
+ * SIG_STOP_FOR_GC wouldn't need to be a rt signal. That has some
+ * performance implications, but does away with the 'rt signal
+ * queue full' problem. */
+ pthread_mutex_unlock(&all_threads_lock); \
+ FSHOW_SIGNAL((stderr,"/gc_start_the_world:end\n"));
}
#endif