#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 */
+int dynamic_values_bytes=4096*sizeof(lispobj); /* same for all threads */
struct thread *all_threads;
volatile lispobj all_threads_lock;
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
+/* When trying to get all_threads_lock one should make sure that
+ * sig_stop_for_gc is not blocked. Else there would be a possible
+ * deadlock: gc locks it, other thread blocks signals, gc sends stop
+ * request to other thread and waits, other thread blocks on lock. */
+void check_sig_stop_for_gc_can_arrive_or_lose()
+{
+ /* Get the current sigmask, by blocking the empty set. */
+ sigset_t empty,current;
+ sigemptyset(&empty);
+ thread_sigmask(SIG_BLOCK, &empty, ¤t);
+ if (sigismember(¤t,SIG_STOP_FOR_GC))
+ lose("SIG_STOP_FOR_GC is blocked\n");
+ if (SymbolValue(INTERRUPTS_ENABLED,arch_os_get_current_thread()) == NIL)
+ lose("interrupts disabled\n");
+ if (arch_pseudo_atomic_atomic(NULL))
+ lose("n pseudo atomic\n");
+}
+
+#ifdef QSHOW_SIGNALS
+#define FSHOW_SIGNAL FSHOW
+#else
+#define FSHOW_SIGNAL(args)
+#endif
+
+#define GET_ALL_THREADS_LOCK(name) \
+ { \
+ sigset_t _newset,_oldset; \
+ sigemptyset(&_newset); \
+ sigaddset_blockable(&_newset); \
+ sigdelset(&_newset,SIG_STOP_FOR_GC); \
+ thread_sigmask(SIG_BLOCK, &_newset, &_oldset); \
+ check_sig_stop_for_gc_can_arrive_or_lose(); \
+ FSHOW_SIGNAL((stderr,"/%s:waiting on lock=%ld, thread=%ld\n",name, \
+ all_threads_lock,arch_os_get_current_thread()->os_thread)); \
+ get_spinlock(&all_threads_lock,(long)arch_os_get_current_thread()); \
+ FSHOW_SIGNAL((stderr,"/%s:got lock, thread=%ld\n", \
+ name,arch_os_get_current_thread()->os_thread));
+
+#define RELEASE_ALL_THREADS_LOCK(name) \
+ FSHOW_SIGNAL((stderr,"/%s:released lock\n",name)); \
+ release_spinlock(&all_threads_lock); \
+ thread_sigmask(SIG_SETMASK,&_oldset,0); \
+ }
+#endif
int
initial_thread_trampoline(struct thread *th)
{
lispobj function;
+#if defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64)
lispobj *args = NULL;
+#endif
+
function = th->unbound_marker;
th->unbound_marker = UNBOUND_MARKER_WIDETAG;
if(arch_os_thread_init(th)==0) return 1;
- if(th->pid < 1) lose("th->pid not set up right");
+ if(th->os_thread < 1) lose("th->os_thread 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
- */
-
#ifdef LISP_FEATURE_SB_THREAD
+
+/* 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;
+ 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();
+ while(th->os_thread<1) sched_yield();
th->state=STATE_RUNNING;
return funcall0(function);
#endif /* LISP_FEATURE_SB_THREAD */
/* 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) {
union per_thread_data *per_thread;
- struct thread *th=0; /* subdue gcc */
+ struct thread *th=0; /* subdue gcc */
void *spaces=0;
/* 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;
+ THREAD_CONTROL_STACK_SIZE+
+ BINDING_STACK_SIZE+
+ ALIEN_STACK_SIZE+
+ dynamic_values_bytes+
+ 32*SIGSTKSZ);
+ 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);
+ 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);
+ 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);
#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
}
+ 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->interrupt_fun=NIL;
+ th->interrupt_fun_lock=0;
+ th->state=STATE_STARTING;
#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);
- 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->interrupt_data = (struct 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;
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)
+void link_thread(struct thread *th,os_thread_t kid_tid)
{
- get_spinlock(&all_threads_lock,kid_pid);
+ if (all_threads) all_threads->prev=th;
th->next=all_threads;
+ th->prev=0;
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
+ /* note that th->os_thread is 0 at this time. We rely on
+ * all_threads_lock to ensure that we don't have >1 thread with
+ * os_thread=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 */
+ protect_control_stack_guard_page(th,1);
+ /* child will not start until this is set */
+ th->os_thread=kid_tid;
}
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 */
+ os_thread_t kid_tid=thread_self();
+ if(th && kid_tid>0) {
+ link_thread(th,kid_tid);
+ initial_thread_trampoline(all_threads); /* no return */
} else lose("can't create initial thread");
}
#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;
- }
-}
-#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);
-}
-
-
-struct thread *find_thread_by_pid(pid_t pid)
-{
- struct thread *th;
- for_each_thread(th)
- if(th->pid==pid) return th;
- return 0;
-}
-
-/* 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;
+ /* 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);
- sigaddset(&newset,SIG_DEQUEUE);
- sigprocmask(SIG_BLOCK, &newset, 0);
+ sigaddset_blockable(&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;
}
-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);
+struct thread *create_thread(lispobj initial_function) {
+ struct thread *th;
+ os_thread_t kid_tid=0;
+ boolean success;
+
+ if(linux_no_threads_p) return 0;
+
+ th=create_thread_struct(initial_function);
+ if(th==0) return 0;
+
+ /* we must not be interrupted here after a successful
+ * create_os_thread, because the kid will be waiting for its
+ * thread struct to be linked */
+ GET_ALL_THREADS_LOCK("create_thread")
+
+ success=create_os_thread(th,&kid_tid);
+ if (success)
+ link_thread(th,kid_tid);
+ else
+ 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);
+
+ RELEASE_ALL_THREADS_LOCK("create_thread")
+
+ if (success)
+ return th;
+ else
+ return 0;
}
-int interrupt_thread(pid_t pid, lispobj function)
+/* called from lisp from the thread object finalizer */
+void reap_dead_thread(struct thread *th)
{
- union sigval sigval;
- sigval.sival_int=function;
-
- return sigqueue(pid, SIG_INTERRUPT_THREAD, sigval);
+ if(th->state!=STATE_DEAD)
+ lose("thread %lx is not joinable, state=%d\n",th,th->state);
+#ifdef LISP_FEATURE_GENCGC
+ {
+ sigset_t newset,oldset;
+ sigemptyset(&newset);
+ sigaddset_blockable(&newset);
+ thread_sigmask(SIG_BLOCK, &newset, &oldset);
+ gc_alloc_update_page_tables(0, &th->alloc_region);
+ release_spinlock(&all_threads_lock);
+ thread_sigmask(SIG_SETMASK,&oldset,0);
+ }
+#endif
+ GET_ALL_THREADS_LOCK("reap_dead_thread")
+ FSHOW((stderr,"/reap_dead_thread: reaping %ld\n",th->os_thread));
+ if(th->prev)
+ th->prev->next=th->next;
+ else all_threads=th->next;
+ if(th->next)
+ th->next->prev=th->prev;
+ RELEASE_ALL_THREADS_LOCK("reap_dead_thread")
+ if(th->tls_cookie>=0) arch_os_thread_cleanup(th);
+ gc_assert(pthread_join(th->os_thread,NULL)==0);
+ 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);
}
-int signal_thread_to_dequeue (pid_t pid)
+int interrupt_thread(struct thread *th, lispobj function)
{
- return kill (pid, SIG_DEQUEUE);
+ /* A thread may also become dead after this test. */
+ if ((th->state != STATE_DEAD)) {
+ /* In clone_threads, if A and B both interrupt C at
+ * approximately the same time, it does not matter: the
+ * second signal will be masked until the handler has
+ * returned from the first one. In pthreads though, we
+ * can't put the knowledge of what function to call into
+ * the siginfo, so we have to store it in the destination
+ * thread, and do it in such a way that A won't clobber
+ * B's interrupt. Hence this stupid linked list.
+ *
+ * This does depend on SIG_INTERRUPT_THREAD being queued
+ * (as POSIX RT signals are): we need to keep
+ * interrupt_fun data for exactly as many signals as are
+ * going to be received by the destination thread.
+ */
+ struct cons *c=alloc_cons(function,NIL);
+ int kill_status;
+ /* interrupt_thread_handler locks this spinlock with
+ * interrupts blocked and it does so for the sake of
+ * arrange_return_to_lisp_function, so we must also block
+ * them. */
+ sigset_t newset,oldset;
+ sigemptyset(&newset);
+ sigaddset_blockable(&newset);
+ thread_sigmask(SIG_BLOCK, &newset, &oldset);
+ get_spinlock(&th->interrupt_fun_lock,
+ (long)arch_os_get_current_thread());
+ kill_status=thread_kill(th->os_thread,SIG_INTERRUPT_THREAD);
+ if(kill_status==0) {
+ ((struct cons *)native_pointer(c))->cdr=th->interrupt_fun;
+ th->interrupt_fun=c;
+ }
+ release_spinlock(&th->interrupt_fun_lock);
+ thread_sigmask(SIG_SETMASK,&oldset,0);
+ return (kill_status ? -1 : 0);
+ }
+ errno=EPERM; return -1;
}
-
-/* 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);
+ FSHOW_SIGNAL((stderr,"/gc_stop_the_world:waiting on lock, thread=%ld\n",
+ th->os_thread));
+ /* keep threads from starting while the world is stopped. */
+ get_spinlock(&all_threads_lock,(long)th);
+ FSHOW_SIGNAL((stderr,"/gc_stop_the_world:got lock, thread=%ld\n",
+ th->os_thread));
+ /* stop all other threads by sending them SIG_STOP_FOR_GC */
+ for(p=all_threads; p; p=p->next) {
+ while(p->state==STATE_STARTING) sched_yield();
+ if((p!=th) && (p->state==STATE_RUNNING)) {
+ FSHOW_SIGNAL((stderr,"/gc_stop_the_world:sending sig_stop to %ld\n",
+ p->os_thread));
+ if(thread_kill(p->os_thread,SIG_STOP_FOR_GC)==-1) {
+ /* we can't kill the thread; assume because it died
+ * since we last checked */
+ p->state=STATE_DEAD;
+ FSHOW_SIGNAL((stderr,"/gc_stop_the_world:assuming %ld dead\n",
+ p->os_thread));
+ }
+ }
+ }
+ FSHOW_SIGNAL((stderr,"/gc_stop_the_world:signals sent\n"));
+ /* wait for the running threads to stop or finish */
+ for(p=all_threads;p;) {
+ gc_assert(p->os_thread!=0);
+ gc_assert(p->state!=STATE_STARTING);
+ if((p==th) || (p->state==STATE_SUSPENDED) ||
+ (p->state==STATE_DEAD)) {
+ 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);
+ /* 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 %ld\n",
+ fixnum_value(p->state));
+ }
+ thread_kill(p->os_thread,SIG_STOP_FOR_GC);
+ }
+ }
+ /* we must wait for all threads to leave stopped state else we
+ * risk signal accumulation and lose any meaning of
+ * thread->state */
+ for(p=all_threads;p;) {
+ if((p==th) || (p->state!=STATE_SUSPENDED)) {
+ p=p->next;
+ }
}
release_spinlock(&all_threads_lock);
+ FSHOW_SIGNAL((stderr,"/gc_start_the_world:end\n"));
}
#endif