lose ("in pseudo atomic section\n");
}
+/* Save sigset (or the current sigmask if 0) if there is no pending
+ * handler, because that means that deferabbles are already blocked.
+ * The purpose is to avoid losing the pending gc signal if a
+ * deferrable interrupt async unwinds between clearing the pseudo
+ * atomic and trapping to GC.*/
+void
+maybe_save_gc_mask_and_block_deferrables(sigset_t *sigset)
+{
+ struct thread *thread = arch_os_get_current_thread();
+ struct interrupt_data *data = thread->interrupt_data;
+ sigset_t oldset;
+ /* Obviously, this function is called when signals may not be
+ * blocked. Let's make sure we are not interrupted. */
+ thread_sigmask(SIG_BLOCK, &blockable_sigset, &oldset);
+#ifndef LISP_FEATURE_SB_THREAD
+ /* With threads a SIG_STOP_FOR_GC and a normal GC may also want to
+ * block. */
+ if (data->gc_blocked_deferrables)
+ lose("gc_blocked_deferrables already true\n");
+#endif
+ if ((!data->pending_handler) &&
+ (!data->gc_blocked_deferrables)) {
+ FSHOW_SIGNAL((stderr,"/setting gc_blocked_deferrables\n"));
+ data->gc_blocked_deferrables = 1;
+ if (sigset) {
+ /* This is the sigmask of some context. */
+ sigcopyset(&data->pending_mask, sigset);
+ sigaddset_deferrable(sigset);
+ thread_sigmask(SIG_SETMASK,&oldset,0);
+ return;
+ } else {
+ /* Operating on the current sigmask. Save oldset and
+ * unblock gc signals. In the end, this is equivalent to
+ * blocking the deferrables. */
+ sigcopyset(&data->pending_mask, &oldset);
+ unblock_gc_signals();
+ return;
+ }
+ }
+ thread_sigmask(SIG_SETMASK,&oldset,0);
+}
+
/* Are we leaving WITH-GCING and already running with interrupts
* enabled, without the protection of *GC-INHIBIT* T and there is gc
* (or stop for gc) pending, but we haven't trapped yet? */
struct interrupt_data *data = thread->interrupt_data;
int interrupt_deferred_p = (data->pending_handler != 0);
int interrupt_pending = (SymbolValue(INTERRUPT_PENDING,thread) != NIL);
+ sigset_t *sigset = os_context_sigmask_addr(context);
/* On PPC pseudo_atomic_interrupted is cleared when coming out of
* handle_allocation_trap. */
#if defined(LISP_FEATURE_GENCGC) && !defined(LISP_FEATURE_PPC)
-#if 0
int interrupts_enabled = (SymbolValue(INTERRUPTS_ENABLED,thread) != NIL);
int gc_inhibit = (SymbolValue(GC_INHIBIT,thread) != NIL);
int gc_pending = (SymbolValue(GC_PENDING,thread) == T);
int pseudo_atomic_interrupted = get_pseudo_atomic_interrupted(thread);
int in_race_p = in_leaving_without_gcing_race_p(thread);
-#endif
/* In the time window between leaving the *INTERRUPTS-ENABLED* NIL
* section and trapping, a SIG_STOP_FOR_GC would see the next
* check fail, for this reason sig_stop_for_gc handler does not
- * call this function. Plus, there may be interrupt lossage when a
- * pseudo atomic is interrupted by a deferrable signal and gc is
- * triggered, too. */
-#if 0
- if (interrupt_deferred_p)
+ * call this function. */
+ if (interrupt_deferred_p) {
if (!(!interrupts_enabled || pseudo_atomic_interrupted || in_race_p))
- lose("Stray deferred interrupt.");
-#endif
-#if 0
+ lose("Stray deferred interrupt.\n");
+ }
if (gc_pending)
if (!(pseudo_atomic_interrupted || gc_inhibit || in_race_p))
- lose("GC_PENDING, but why?.");
+ lose("GC_PENDING, but why?\n");
#if defined(LISP_FEATURE_SB_THREAD)
{
int stop_for_gc_pending =
(SymbolValue(STOP_FOR_GC_PENDING,thread) != NIL);
if (stop_for_gc_pending)
if (!(pseudo_atomic_interrupted || gc_inhibit || in_race_p))
- lose("STOP_FOR_GC_PENDING, but why?.");
+ lose("STOP_FOR_GC_PENDING, but why?\n");
}
#endif
#endif
-#endif
if (interrupt_pending && !interrupt_deferred_p)
- lose("INTERRUPT_PENDING but not pending handler.");
- if (interrupt_deferred_p)
- check_deferrables_blocked_in_sigset_or_lose
- (os_context_sigmask_addr(context));
- else
- check_deferrables_unblocked_in_sigset_or_lose
- (os_context_sigmask_addr(context));
+ lose("INTERRUPT_PENDING but not pending handler.\n");
+ if ((data->gc_blocked_deferrables) && interrupt_pending)
+ lose("gc_blocked_deferrables and interrupt pending\n.");
+ if (data->gc_blocked_deferrables)
+ check_deferrables_blocked_in_sigset_or_lose(sigset);
+ if (interrupt_pending || interrupt_deferred_p)
+ check_deferrables_blocked_in_sigset_or_lose(sigset);
+ else {
+ check_deferrables_unblocked_in_sigset_or_lose(sigset);
+ /* If deferrables are unblocked then we are open to signals
+ * that run lisp code. */
+ check_gc_signals_unblocked_in_sigset_or_lose(sigset);
+ }
}
/* When we catch an internal error, should we pass it back to Lisp to
/* Win32 only needs to handle the GC cases (for now?) */
- struct thread *thread;
+ struct thread *thread = arch_os_get_current_thread();
+ struct interrupt_data *data = thread->interrupt_data;
if (arch_pseudo_atomic_atomic(context)) {
lose("Handling pending interrupt in pseduo atomic.");
}
- thread = arch_os_get_current_thread();
-
FSHOW_SIGNAL((stderr, "/entering interrupt_handle_pending\n"));
check_blockables_blocked_or_lose();
- /* If pseudo_atomic_interrupted is set then the interrupt is going
- * to be handled now, ergo it's safe to clear it. */
- arch_clear_pseudo_atomic_interrupted(context);
+ /* If GC/SIG_STOP_FOR_GC stroke during PA and there was no pending
+ * handler, then the pending mask was saved and
+ * gc_blocked_deferrables set. Hence, there can be no pending
+ * handler and it's safe to restore the pending mask.
+ *
+ * Note, that if gc_blocked_deferrables is false we may still have
+ * to GC. In this case, we are coming out of a WITHOUT-GCING. */
+ if (data->gc_blocked_deferrables) {
+ if (data->pending_handler)
+ lose("GC blocked deferrables but still got a pending handler.");
+ if (SymbolValue(GC_INHIBIT,thread)!=NIL)
+ lose("GC blocked deferrables while GC is inhibited.");
+ /* restore the saved signal mask from the original signal
+ * (the one that interrupted us during the critical
+ * section) into the os_context for the signal we're
+ * currently in the handler for. This should ensure that
+ * when we return from the handler the blocked signals are
+ * unblocked */
+ sigcopyset(os_context_sigmask_addr(context), &data->pending_mask);
+ data->gc_blocked_deferrables = 0;
+ }
if (SymbolValue(GC_INHIBIT,thread)==NIL) {
+ void *original_pending_handler = data->pending_handler;
+
#ifdef LISP_FEATURE_SB_THREAD
if (SymbolValue(STOP_FOR_GC_PENDING,thread) != NIL) {
/* STOP_FOR_GC_PENDING and GC_PENDING are cleared by
* the signal handler if it actually stops us. */
+ arch_clear_pseudo_atomic_interrupted(context);
sig_stop_for_gc_handler(SIG_STOP_FOR_GC,NULL,context);
} else
#endif
* is used in SUB-GC as part of the mechanism to supress
* recursive gcs.*/
if (SymbolValue(GC_PENDING,thread) == T) {
+ /* Two reasons for doing this. First, if there is a
+ * pending handler we don't want to run. Second, we are
+ * going to clear pseudo atomic interrupted to avoid
+ * spurious trapping on every allocation in SUB_GC and
+ * having a pending handler with interrupts enabled and
+ * without pseudo atomic interrupted breaks an
+ * invariant. */
+ if (data->pending_handler) {
+ bind_variable(ALLOW_WITH_INTERRUPTS, NIL, thread);
+ bind_variable(INTERRUPTS_ENABLED, NIL, thread);
+ }
+
+ arch_clear_pseudo_atomic_interrupted(context);
+
/* GC_PENDING is cleared in SUB-GC, or if another thread
* is doing a gc already we will get a SIG_STOP_FOR_GC and
* that will clear it. */
- maybe_gc(context);
+ if (!maybe_gc(context))
+ lose("GC not inhibited but maybe_gc did not GC.");
+
+ if (data->pending_handler) {
+ unbind(thread);
+ unbind(thread);
+ }
+ } else if (SymbolValue(GC_PENDING,thread) != NIL) {
+ /* It's not NIL or T so GC_PENDING is :IN-PROGRESS. If
+ * GC-PENDING is not NIL then we cannot trap on pseudo
+ * atomic due to GC (see if(GC_PENDING) logic in
+ * cheneygc.c an gengcgc.c), plus there is a outer
+ * WITHOUT-INTERRUPTS SUB_GC, so how did we end up
+ * here? */
+ lose("Trapping to run pending handler while GC in progress.");
}
+
check_blockables_blocked_or_lose();
+
+ /* No GC shall be lost. If SUB_GC triggers another GC then
+ * that should be handled on the spot. */
+ if (SymbolValue(GC_PENDING,thread) != NIL)
+ lose("GC_PENDING after doing gc.");
+#ifdef LISP_FEATURE_SB_THREAD
+ if (SymbolValue(STOP_FOR_GC_PENDING,thread) != NIL)
+ lose("STOP_FOR_GC_PENDING after doing gc.");
+#endif
+ /* Check two things. First, that gc does not clobber a handler
+ * that's already pending. Second, that there is no interrupt
+ * lossage: if original_pending_handler was NULL then even if
+ * an interrupt arrived during GC (POST-GC, really) it was
+ * handled. */
+ if (original_pending_handler != data->pending_handler)
+ lose("pending handler changed in gc: %x -> %d.",
+ original_pending_handler, data->pending_handler);
}
#ifndef LISP_FEATURE_WIN32
- /* we may be here only to do the gc stuff, if interrupts are
- * enabled run the pending handler */
- if (SymbolValue(INTERRUPTS_ENABLED,thread) != NIL) {
- struct interrupt_data *data = thread->interrupt_data;
-
- /* There may be no pending handler, because it was only a gc
- * that had to be executed or because pseudo atomic triggered
- * twice for a single interrupt. For the interested reader,
- * that may happen if an interrupt hits after the interrupted
- * flag is cleared but before pseudo-atomic is set and a
- * pseudo atomic is interrupted in that interrupt. */
- if (data->pending_handler) {
-
- /* If we're here as the result of a pseudo-atomic as opposed
- * to WITHOUT-INTERRUPTS, then INTERRUPT_PENDING is already
- * NIL, because maybe_defer_handler sets
- * PSEUDO_ATOMIC_INTERRUPTED only if interrupts are enabled.*/
- SetSymbolValue(INTERRUPT_PENDING, NIL, thread);
-
- /* restore the saved signal mask from the original signal (the
- * one that interrupted us during the critical section) into the
- * os_context for the signal we're currently in the handler for.
- * This should ensure that when we return from the handler the
- * blocked signals are unblocked */
- sigcopyset(os_context_sigmask_addr(context), &data->pending_mask);
-
- /* This will break on sparc linux: the deferred handler really wants
- * to be called with a void_context */
- run_deferred_handler(data,(void *)context);
- }
+ /* There may be no pending handler, because it was only a gc that
+ * had to be executed or because Lisp is a bit too eager to call
+ * DO-PENDING-INTERRUPT. */
+ if ((SymbolValue(INTERRUPTS_ENABLED,thread) != NIL) &&
+ (data->pending_handler)) {
+ /* No matter how we ended up here, clear both
+ * INTERRUPT_PENDING and pseudo atomic interrupted. It's safe
+ * because we checked above that there is no GC pending. */
+ SetSymbolValue(INTERRUPT_PENDING, NIL, thread);
+ arch_clear_pseudo_atomic_interrupted(context);
+ /* Restore the sigmask in the context. */
+ sigcopyset(os_context_sigmask_addr(context), &data->pending_mask);
+ /* This will break on sparc linux: the deferred handler really
+ * wants to be called with a void_context */
+ run_deferred_handler(data,(void *)context);
}
+ /* It is possible that the end of this function was reached
+ * without never actually doing anything, the tests in Lisp for
+ * when to call receive-pending-interrupt are not exact. */
+ FSHOW_SIGNAL((stderr, "/exiting interrupt_handle_pending\n"));
#endif
}
\f
info_sap,
context_sap);
} else {
+ /* This cannot happen in sane circumstances. */
FSHOW_SIGNAL((stderr,"/calling C-level handler\n"));
void (*pending_handler) (int, siginfo_t*, void*)=data->pending_handler;
data->pending_handler=0;
+ FSHOW_SIGNAL((stderr, "/running deferred handler %p\n", pending_handler));
(*pending_handler)(data->pending_signal,&(data->pending_info), v_context);
}
if (SymbolValue(INTERRUPT_PENDING,thread) != NIL)
lose("interrupt already pending\n");
+ if (thread->interrupt_data->pending_handler)
+ lose("there is a pending handler already (PA)\n");
+ if (data->gc_blocked_deferrables)
+ lose("maybe_defer_handler: gc_blocked_deferrables true\n");
check_interrupt_context_or_lose(context);
/* If interrupts are disabled then INTERRUPT_PENDING is set and
* not PSEDUO_ATOMIC_INTERRUPTED. This is important for a pseudo
store_signal_data_for_later(data,handler,signal,info,context);
SetSymbolValue(INTERRUPT_PENDING, T,thread);
FSHOW_SIGNAL((stderr,
- "/maybe_defer_handler(%x,%d): deferred\n",
- (unsigned int)handler,signal));
+ "/maybe_defer_handler(%x,%d): deferred (RACE=%d)\n",
+ (unsigned int)handler,signal,
+ in_leaving_without_gcing_race_p(thread)));
check_interrupt_context_or_lose(context);
return 1;
}
FSHOW_SIGNAL((stderr, "/store_signal_data_for_later: signal: %d\n",
signal));
- if(context) {
- /* the signal mask in the context (from before we were
- * interrupted) is copied to be restored when
- * run_deferred_handler happens. Then the usually-blocked
- * signals are added to the mask in the context so that we are
- * running with blocked signals when the handler returns */
- sigcopyset(&(data->pending_mask),os_context_sigmask_addr(context));
- sigaddset_deferrable(os_context_sigmask_addr(context));
- }
+ if(!context)
+ lose("Null context");
+
+ /* the signal mask in the context (from before we were
+ * interrupted) is copied to be restored when run_deferred_handler
+ * happens. Then the usually-blocked signals are added to the mask
+ * in the context so that we are running with blocked signals when
+ * the handler returns */
+ sigcopyset(&(data->pending_mask),os_context_sigmask_addr(context));
+ sigaddset_deferrable(os_context_sigmask_addr(context));
}
static void
#ifdef LISP_FEATURE_SB_THREAD
+/* This function must not cons, because that may trigger a GC. */
void
sig_stop_for_gc_handler(int signal, siginfo_t *info, void *void_context)
{
} else if (arch_pseudo_atomic_atomic(context)) {
SetSymbolValue(STOP_FOR_GC_PENDING,T,thread);
arch_set_pseudo_atomic_interrupted(context);
+ maybe_save_gc_mask_and_block_deferrables
+ (os_context_sigmask_addr(context));
FSHOW_SIGNAL((stderr,"sig_stop_for_gc deferred (PA)\n"));
return;
}
+ FSHOW_SIGNAL((stderr, "/sig_stop_for_gc_handler\n"));
+
/* Not PA and GC not inhibited -- we can stop now. */
/* need the context stored so it can have registers scavenged */
projects / sbcl.git / commitdiff