void check_list(int n) { list_element *p; int i; for (i = 1; i <= n; ++i) marks[i] = 0; for (p = (list_element *)AO_REAL_HEAD_PTR(the_list); p != 0; p = (list_element *)AO_REAL_NEXT_PTR(p -> next)) { i = p -> data; if (i > n || i <= 0) { fprintf(stderr, "Found erroneous list element %d\n", i); abort(); } if (marks[i] != 0) { fprintf(stderr, "Found duplicate list element %d\n", i); abort(); } marks[i] = 1; } for (i = 1; i <= n; ++i) if (marks[i] != 1) { fprintf(stderr, "Missing list element %d\n", i); abort(); } }
AO_t * AO_stack_pop_explicit_aux_acquire(volatile AO_t *list, AO_stack_aux * a) { unsigned i; int j = 0; AO_t first; AO_t * first_ptr; AO_t next; retry: first = AO_load(list); if (0 == first) return 0; /* Insert first into aux black list. */ /* This may spin if more than AO_BL_SIZE removals using auxiliary */ /* structure a are currently in progress. */ for (i = 0; ; ) { if (PRECHECK(a -> AO_stack_bl[i]) AO_compare_and_swap_acquire(a->AO_stack_bl+i, 0, first)) break; ++i; if ( i >= AO_BL_SIZE ) { i = 0; AO_pause(++j); } } assert(i < AO_BL_SIZE); assert(a -> AO_stack_bl[i] == first); /* First is on the auxiliary black list. It may be removed by */ /* another thread before we get to it, but a new insertion of x */ /* cannot be started here. */ /* Only we can remove it from the black list. */ /* We need to make sure that first is still the first entry on the */ /* list. Otherwise it's possible that a reinsertion of it was */ /* already started before we added the black list entry. */ if (AO_EXPECT_FALSE(first != AO_load(list))) { AO_store_release(a->AO_stack_bl+i, 0); goto retry; } first_ptr = AO_REAL_NEXT_PTR(first); next = AO_load(first_ptr); if (AO_EXPECT_FALSE(!AO_compare_and_swap_release(list, first, next))) { AO_store_release(a->AO_stack_bl+i, 0); goto retry; } assert(*list != first); /* Since we never insert an entry on the black list, this cannot have */ /* succeeded unless first remained on the list while we were running. */ /* Thus its next link cannot have changed out from under us, and we */ /* removed exactly one entry and preserved the rest of the list. */ /* Note that it is quite possible that an additional entry was */ /* inserted and removed while we were running; this is OK since the */ /* part of the list following first must have remained unchanged, and */ /* first must again have been at the head of the list when the */ /* compare_and_swap succeeded. */ AO_store_release(a->AO_stack_bl+i, 0); return first_ptr; }
void print_list(void) { list_element *p; for (p = (list_element *)AO_REAL_HEAD_PTR(the_list); p != 0; p = (list_element *)AO_REAL_NEXT_PTR(p -> next)) printf("%d\n", p -> data); }