#include "sbcl.h"
#include "runtime.h"
-#include "validate.h" /* for CONTROL_STACK_SIZE etc */
+#include "validate.h" /* for CONTROL_STACK_SIZE etc */
+#include "alloc.h"
#include "thread.h"
#include "arch.h"
#include "target-arch-os.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;
+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;
-int
+#ifdef LISP_FEATURE_SB_THREAD
+
+pthread_mutex_t all_threads_lock = PTHREAD_MUTEX_INITIALIZER;
+
+/* 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 cannot arrive: it is blocked\n");
+ if (SymbolValue(GC_INHIBIT,arch_os_get_current_thread()) != NIL)
+ lose("SIG_STOP_FOR_GC cannot arrive: gc is inhibited\n");
+ if (arch_pseudo_atomic_atomic(NULL))
+ lose("SIG_STOP_FOR_GC cannot arrive: in pseudo atomic\n");
+}
+
+#define GET_ALL_THREADS_LOCK(name) \
+ { \
+ sigset_t _newset,_oldset; \
+ sigemptyset(&_newset); \
+ sigaddset_deferrable(&_newset); \
+ thread_sigmask(SIG_BLOCK, &_newset, &_oldset); \
+ check_sig_stop_for_gc_can_arrive_or_lose(); \
+ FSHOW_SIGNAL((stderr,"/%s:waiting on lock=%ld, thread=%lu\n",name, \
+ all_threads_lock,arch_os_get_current_thread()->os_thread)); \
+ pthread_mutex_lock(&all_threads_lock); \
+ FSHOW_SIGNAL((stderr,"/%s:got lock, thread=%lu\n", \
+ name,arch_os_get_current_thread()->os_thread));
+
+#define RELEASE_ALL_THREADS_LOCK(name) \
+ FSHOW_SIGNAL((stderr,"/%s:released lock\n",name)); \
+ pthread_mutex_unlock(&all_threads_lock); \
+ thread_sigmask(SIG_SETMASK,&_oldset,0); \
+ }
+#endif
+
+
+#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 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) || defined(LISP_FEATURE_X86_64)
return call_into_lisp_first_time(function,args,0);
#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;
+ int result;
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) {
+ /* FIXME: handle error */
+ lose("arch_os_thread_init failed\n");
+ }
/* wait here until our thread is linked into all_threads: see below */
- while(th->pid<1) sched_yield();
+ {
+ volatile os_thread_t *tid=&th->os_thread;
+ while(*tid<1) sched_yield();
+ }
th->state=STATE_RUNNING;
- return funcall0(function);
+ result = funcall0(function);
+ th->state=STATE_DEAD;
+ return result;
}
#endif /* LISP_FEATURE_SB_THREAD */
+#define THREAD_STRUCT_SIZE (THREAD_CONTROL_STACK_SIZE + BINDING_STACK_SIZE + \
+ ALIEN_STACK_SIZE + dynamic_values_bytes + \
+ 32 * SIGSTKSZ)
+
+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;
/* 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);
+ spaces=os_validate(0, THREAD_STRUCT_SIZE);
if(!spaces)
- return NULL;
+ 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);
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-N_WORD_BYTES);
+ + ALIEN_STACK_SIZE-N_WORD_BYTES);
#else
th->alien_stack_pointer=((void *)th->alien_stack_start);
#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 */
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->interrupt_data = (struct interrupt_data *)
+ os_validate(0,(sizeof (struct interrupt_data)));
+ if (!th->interrupt_data) {
+ free_thread_struct(th);
+ return 0;
+ }
+ 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;
}
-void link_thread(struct thread *th,pid_t kid_pid)
+static void
+link_thread(struct thread *th,os_thread_t kid_tid)
{
- sigset_t newset,oldset;
- sigemptyset(&newset);
- sigaddset_blockable(&newset);
- sigprocmask(SIG_BLOCK, &newset, &oldset);
-
- 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);
-
- sigprocmask(SIG_SETMASK,&oldset,0);
- 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;
+ FSHOW((stderr,"/created thread %lu\n",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) {
+
+#ifndef __USE_XOPEN2K
+extern int pthread_attr_setstack (pthread_attr_t *__attr, void *__stackaddr,
+ size_t __stacksize);
+#endif
+
+boolean create_os_thread(struct thread *th,os_thread_t *kid_tid)
+{
+ /* 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, since gc_stop_the_world
+ * waits until the child leaves STATE_STARTING. And why not let gc
+ * proceed as soon as possible? */
+ 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 *create_thread(lispobj initial_function) {
struct thread *th;
- pid_t kid_pid=0;
+ 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;
- kid_pid=clone(new_thread_trampoline,
- (((void*)th->control_stack_start)+
- THREAD_CONTROL_STACK_SIZE-16),
- CLONE_FILES|SIG_THREAD_EXIT|CLONE_VM,th);
-
- if(kid_pid>0) {
- link_thread(th,kid_pid);
- return th->pid;
- } 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);
- return 0;
- }
-}
-#endif
-struct thread *find_thread_by_pid(pid_t pid)
-{
- struct thread *th;
- for_each_thread(th)
- if(th->pid==pid) return th;
- 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")
-#if defined LISP_FEATURE_SB_THREAD
-/* This is not needed unless #+SB-THREAD, as there's a trivial null
- * unithread definition. */
+ success=create_os_thread(th,&kid_tid);
+ if (success)
+ link_thread(th,kid_tid);
+ else
+ free_thread_struct(th);
-void mark_dead_threads()
-{
- pid_t kid;
- int status;
- while(1) {
- kid=waitpid(-1,&status,__WALL|WNOHANG);
- if(kid<=0) break;
- if(WIFEXITED(status) || WIFSIGNALED(status)) {
- struct thread *th=find_thread_by_pid(kid);
- if(th) th->state=STATE_DEAD;
- }
- }
+ RELEASE_ALL_THREADS_LOCK("create_thread")
+
+ if (success)
+ return th;
+ else
+ return 0;
}
-void reap_dead_threads()
+/* called from lisp from the thread object finalizer */
+void reap_dead_thread(struct thread *th)
{
- struct thread *th,*next,*prev=0;
- th=all_threads;
- while(th) {
- next=th->next;
- if(th->state==STATE_DEAD) {
- funcall1(SymbolFunction(HANDLE_THREAD_EXIT),make_fixnum(th->pid));
+ if(th->state!=STATE_DEAD)
+ lose("thread %p is not joinable, state=%d\n",th,th->state);
#ifdef LISP_FEATURE_GENCGC
- gc_alloc_update_page_tables(0, &th->alloc_region);
-#endif
- get_spinlock(&all_threads_lock,th->pid);
- if(prev) prev->next=next;
- else all_threads=next;
- release_spinlock(&all_threads_lock);
- if(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);
- } else
- prev=th;
- th=next;
+ {
+ sigset_t newset,oldset;
+ sigemptyset(&newset);
+ sigaddset_blockable(&newset);
+ thread_sigmask(SIG_BLOCK, &newset, &oldset);
+ gc_alloc_update_page_tables(0, &th->alloc_region);
+ thread_sigmask(SIG_SETMASK,&oldset,0);
}
+#endif
+ GET_ALL_THREADS_LOCK("reap_dead_thread")
+ FSHOW((stderr,"/reap_dead_thread: reaping %lu\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);
+ free_thread_struct(th);
}
-/* 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. */
-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);
-}
-
-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);
-}
-
-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;
- struct thread *th;
- sigval.sival_int=function;
- for_each_thread(th)
- if((th->pid==pid) && (th->state != STATE_DEAD))
- return sigqueue(pid, SIG_INTERRUPT_THREAD, sigval);
- errno=EPERM; return -1;
+ 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 interrupt_thread(struct thread *th, lispobj function)
{
- return kill (pid, SIG_DEQUEUE);
+ /* 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.
+ */
+ lispobj c=alloc_cons(function,NIL);
+ sigset_t newset,oldset;
+ sigemptyset(&newset);
+ /* interrupt_thread_handler locks this spinlock with blockables
+ * blocked (it does so for the sake of
+ * arrange_return_to_lisp_function), so we must also block them or
+ * else SIG_STOP_FOR_GC and all_threads_lock will find a way to
+ * deadlock. */
+ sigaddset_blockable(&newset);
+ thread_sigmask(SIG_BLOCK, &newset, &oldset);
+ if (th == arch_os_get_current_thread())
+ lose("cannot interrupt current thread");
+ get_spinlock(&th->interrupt_fun_lock,
+ (long)arch_os_get_current_thread());
+ ((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);
+ /* Called from lisp with the thread object as a parameter. Thus,
+ * the object cannot be garbage collected and consequently reaped
+ * and joined. Because it's not joined, kill should work (even if
+ * the thread has died/exited). */
+ {
+ int status=kill_thread_safely(th->os_thread,SIG_INTERRUPT_THREAD);
+ if (status==0) {
+ return 0;
+ } else if (status==ESRCH) {
+ /* This thread has exited. */
+ th->interrupt_fun=NIL;
+ errno=ESRCH;
+ return -1;
+ } else {
+ lose("cannot send SIG_INTERRUPT_THREAD to thread=%lu: %d, %s",
+ th->os_thread,status,strerror(status));
+ }
+ }
}
-
-/* stopping the world is a two-stage process. From this thread we signal
+/* 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 kills _itself_ with SIGSTOP.
+ * 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;
- do {
- finished=1;
- for(p=all_threads,old_pid=p->pid; p; p=p->next) {
- if(p==th) continue;
- if(p->state==STATE_RUNNING) {
- p->state=STATE_STOPPING;
- if(kill(p->pid,SIG_STOP_FOR_GC)==-1) {
- /* we can't kill the process; assume because it
- * died already (and its parent is dead so never
- * saw the SIGCHLD) */
- p->state=STATE_DEAD;
- }
- }
- if((p->state!=STATE_STOPPED) &&
- (p->state!=STATE_DEAD)) {
- finished=0;
- }
- }
- if(old_pid!=all_threads->pid) {
- finished=0;
- }
- } 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) {
+ while(p->state==STATE_STARTING) sched_yield();
+ 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",
+ 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;) {
+ 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;
+ } else {
+ sched_yield();
+ }
+ }
+ FSHOW_SIGNAL((stderr,"/gc_stop_the_world:end\n"));
}
void gc_start_the_world()
{
struct thread *p,*th=arch_os_get_current_thread();
+ 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_lock, but it won't have been stopped so won't need
+ * 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) || (p->state==STATE_DEAD)) 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",
+ p->os_thread,status,strerror(status));
+ }
+ }
}
+ /* 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
projects / sbcl.git / blobdiff