diff options
| -rw-r--r-- | ChangeLog | 31 | ||||
| -rw-r--r-- | gc.c | 100 | ||||
| -rw-r--r-- | txr.1 | 5 |
3 files changed, 97 insertions, 39 deletions
@@ -1,3 +1,34 @@ +2015-05-01 Kaz Kylheku <kaz@kylheku.com> + + Fix corruption triggered by extended gc disabling. + + The issue is that when gc is disabled, the gc function + does nothing. But various code depends on calls to gc() + doing something, like making space available in various + static arrays. + + When gc is disabled for long periods, there are issues, + like array overruns. + + * gc.c (gc): Must no longer be called at all if gc_enabled is false, + and asserts that it is true. Callers must check the gc_enabled + flag and implement appropriate cases. + (make_obj): Only call gc when gc_enabled is true. + If there is no space in the freshobj array after trying gc, + or gc couldn't be tried because it is disabled, then + schedule a full gc. + (gc_set): If the checkobj array is full, only call gc if gc + is enabled, otherwise schedule a full_gc. + (gc_mutated): Do not assume that the mutobj array has room + for another object; only set the object's generation to -1 + and put it into the array if there is room. Similarly to + gc_set, do a gc if there is no room, but if gc is not enabled, then + schedule a full gc. + (gc_wrap): Only call gc if gc_enabled is true, and return t in + that case rathe than nil. + + * txr.1: Document return value of sys:gc function. + 2015-04-30 Kaz Kylheku <kaz@kylheku.com> Fix source location for dangling unquotes and splices. @@ -169,14 +169,18 @@ val make_obj(void) assert (!async_sig_enabled); #if CONFIG_GEN_GC - if (opt_gc_debug || freshobj_idx >= FRESHOBJ_VEC_SIZE || - malloc_delta >= opt_gc_delta) + if ((opt_gc_debug || freshobj_idx >= FRESHOBJ_VEC_SIZE || + malloc_delta >= opt_gc_delta) && + gc_enabled) { gc(); prev_malloc_bytes = malloc_bytes; } + + if (freshobj_idx >= FRESHOBJ_VEC_SIZE) + full_gc = 1; #else - if (opt_gc_debug || malloc_delta >= opt_gc_delta) { + if ((opt_gc_debug || malloc_delta >= opt_gc_delta) && gc_enabled) { gc(); prev_malloc_bytes = malloc_bytes; } @@ -211,8 +215,15 @@ val make_obj(void) #endif switch (tries) { - case 0: gc(); break; - case 1: more(); break; + case 0: + if (gc_enabled) { + gc(); + break; + } + /* fallthrough */ + case 1: + more(); + break; } } @@ -647,44 +658,43 @@ void gc(void) int full_gc_next_time = 0; static int gc_counter; #endif + int swept; + mach_context_t mc; - if (gc_enabled) { - int swept; - - mach_context_t mc; - save_context(mc); - gc_enabled = 0; - mark(&mc, &gc_stack_top); - hash_process_weak(); - prepare_finals(); - swept = sweep(); + assert (gc_enabled); + + save_context(mc); + gc_enabled = 0; + mark(&mc, &gc_stack_top); + hash_process_weak(); + prepare_finals(); + swept = sweep(); #if CONFIG_GEN_GC #if 0 - printf("sweep: freed %d full_gc == %d exhausted == %d\n", - (int) swept, full_gc, exhausted); + printf("sweep: freed %d full_gc == %d exhausted == %d\n", + (int) swept, full_gc, exhausted); #endif - if (++gc_counter >= FULL_GC_INTERVAL || - freshobj_idx >= FRESHOBJ_VEC_SIZE) - { - full_gc_next_time = 1; - gc_counter = 0; - } + if (++gc_counter >= FULL_GC_INTERVAL || + freshobj_idx >= FRESHOBJ_VEC_SIZE) + { + full_gc_next_time = 1; + gc_counter = 0; + } - if (exhausted && full_gc && swept < 3 * HEAP_SIZE / 4) - more(); + if (exhausted && full_gc && swept < 3 * HEAP_SIZE / 4) + more(); #else - if (swept < 3 * HEAP_SIZE / 4) - more(); + if (swept < 3 * HEAP_SIZE / 4) + more(); #endif #if CONFIG_GEN_GC - checkobj_idx = 0; - mutobj_idx = 0; - full_gc = full_gc_next_time; + checkobj_idx = 0; + mutobj_idx = 0; + full_gc = full_gc_next_time; #endif - call_finals(); - gc_enabled = 1; - } + call_finals(); + gc_enabled = 1; } int gc_state(int enabled) @@ -731,9 +741,13 @@ val gc_set(loc lo, val obj) if (checkobj_idx < CHECKOBJ_VEC_SIZE) { obj->t.gen = -1; checkobj[checkobj_idx++] = obj; - } else { + } else if (gc_enabled) { gc(); - /* obj can't be in gen 0 because there are no baby objects after gc */ + /* obj can't be in gen 0 because there are no baby objects after gc */ + } else { + /* We have no space to in checkobj record this backreference, and gc is + not available to promote obj to gen 0. We must schedule a full gc. */ + full_gc = 1; } } @@ -747,12 +761,17 @@ val gc_mutated(val obj) already been noted. And if a full gc is coming, don't bother. */ if (full_gc || obj->t.gen <= 0) return obj; - obj->t.gen = -1; /* Store in mutobj array *before* triggering gc, otherwise baby objects referenced by obj could be reclaimed! */ - mutobj[mutobj_idx++] = obj; - if (mutobj_idx >= MUTOBJ_VEC_SIZE) + if (mutobj_idx < MUTOBJ_VEC_SIZE) { + obj->t.gen = -1; + mutobj[mutobj_idx++] = obj; + } else if (gc_enabled) { gc(); + } else { + full_gc = 1; + } + return obj; } @@ -772,7 +791,10 @@ static val gc_set_delta(val delta) static val gc_wrap(void) { - gc(); + if (gc_enabled) { + gc(); + return t; + } return nil; } @@ -27698,6 +27698,11 @@ function triggers garbage collection. Garbage collection means that unreachable objects are identified and reclaimed, so that their storage can be re-used. +The function returns +.code nil +if garbage collection is disabled (and consequently nothing is done), otherwise +.codn t . + .coNP Function @ sys:gc-set-delta .synb .mets (sys:gc-set-delta << bytes ) |