gcext: add ptls argument to task scanner

Access to ptls is generally necessary when marking objects so it
makes sense to pass it to the task scanner.

We pass it as the last argument to the callback so that existing
consumers of this API hopefully keep working, they will just
ignore this new argument.

Author: fingolfin

src/gc.c

@@ -2726,7 +2726,7 @@ FORCE_INLINE void gc_mark_outrefs(jl_ptls_t ptls, jl_gc_markqueue_t *mq, void *_
                 if (gc_cblist_task_scanner) {
                     int16_t tid = jl_atomic_load_relaxed(&ta->tid);
                     gc_invoke_callbacks(jl_gc_cb_task_scanner_t, gc_cblist_task_scanner,
-                                        (ta, tid != -1 && ta == gc_all_tls_states[tid]->root_task));
+                                        (ta, tid != -1 && ta == gc_all_tls_states[tid]->root_task, ptls));
                 }
         #ifdef COPY_STACKS
                 void *stkbuf = ta->stkbuf;

src/julia_gcext.h

@@ -15,7 +15,7 @@ extern "C" {
 // along with custom mark functions must not alter the GC state except
 // through calling jl_gc_mark_queue_obj() and jl_gc_mark_queue_objarray().
 typedef void (*jl_gc_cb_root_scanner_t)(int full) JL_NOTSAFEPOINT;
-typedef void (*jl_gc_cb_task_scanner_t)(jl_task_t *task, int full) JL_NOTSAFEPOINT;
+typedef void (*jl_gc_cb_task_scanner_t)(jl_task_t *task, int is_root_task, jl_ptls_t ptls) JL_NOTSAFEPOINT;
 
 // Callbacks that are invoked before and after a collection.
 typedef void (*jl_gc_cb_pre_gc_t)(int full) JL_NOTSAFEPOINT;

test/gcext/gcext.c

@@ -284,7 +284,6 @@ typedef struct {
 static jl_datatype_t *datatype_stack_internal;
 static jl_datatype_t *datatype_stack_external;
 static jl_datatype_t *datatype_stack;
-static jl_ptls_t ptls;
 
 static size_t gc_alloc_size(jl_value_t *val)
 {
@@ -333,7 +332,7 @@ int internal_obj_scan(jl_value_t *val)
     }
 }
 
-dynstack_t *allocate_stack_mem(size_t capacity)
+dynstack_t *allocate_stack_mem(jl_ptls_t ptls, size_t capacity)
 {
     size_t size = offsetof(dynstack_t, data) + capacity * sizeof(jl_value_t *);
     jl_datatype_t *type = datatype_stack_internal;
@@ -377,13 +376,14 @@ jl_value_t *stk_type()
 
 // Create a new stack object
 
-jl_value_t *stk_make()
+jl_value_t *stk_make(void)
 {
+    jl_ptls_t ptls = jl_get_ptls_states();
     jl_value_t *hdr =
             jl_gc_alloc_typed(ptls, sizeof(jl_value_t *), datatype_stack);
     JL_GC_PUSH1(hdr);
     *(dynstack_t **)hdr = NULL;
-    dynstack_t *stk = allocate_stack_mem(8);
+    dynstack_t *stk = allocate_stack_mem(ptls, 8);
     *(dynstack_t **)hdr = stk;
     jl_gc_schedule_foreign_sweepfunc(ptls, (jl_value_t *)(stk));
     JL_GC_POP();
@@ -408,7 +408,8 @@ void stk_push(jl_value_t *s, jl_value_t *v)
         jl_gc_wb((jl_value_t *)stk, v);
     }
     else {
-        dynstack_t *newstk = allocate_stack_mem(stk->capacity * 3 / 2 + 1);
+        jl_ptls_t ptls = jl_get_ptls_states();
+        dynstack_t *newstk = allocate_stack_mem(ptls, stk->capacity * 3 / 2 + 1);
         newstk->size = stk->size;
         memcpy(newstk->data, stk->data, sizeof(jl_value_t *) * stk->size);
         *(dynstack_t **)s = newstk;
@@ -453,6 +454,7 @@ static jl_module_t *module;
 
 void root_scanner(int full)
 {
+    jl_ptls_t ptls = jl_get_ptls_states();
     for (int i = 0; i < NAUXROOTS; i++) {
         if (aux_roots[i])
             jl_gc_mark_queue_obj(ptls, aux_roots[i]);
@@ -477,7 +479,7 @@ static int stack_grows_down(void) {
   return is_lower_stack_frame_ptr(buf);
 }
 
-void task_scanner(jl_task_t *task, int root_task)
+void task_scanner(jl_task_t *task, int root_task, jl_ptls_t ptls)
 {
     int var_on_frame;
 
@@ -603,7 +605,6 @@ int main()
     jl_init();
     if (jl_gc_enable_conservative_gc_support() < 0)
         abort();
-    ptls = jl_get_ptls_states();
     jl_gc_set_cb_root_scanner(root_scanner, 1);
     jl_gc_set_cb_task_scanner(task_scanner, 1);
     jl_gc_set_cb_pre_gc(pre_gc_func, 1);