diff options
Diffstat (limited to 'src/core/support/stack_lockfree.c')
| -rw-r--r-- | src/core/support/stack_lockfree.c | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/src/core/support/stack_lockfree.c b/src/core/support/stack_lockfree.c index 2844330379..f24e272207 100644 --- a/src/core/support/stack_lockfree.c +++ b/src/core/support/stack_lockfree.c @@ -72,6 +72,11 @@ typedef union lockfree_node { struct gpr_stack_lockfree { lockfree_node *entries; lockfree_node head; /* An atomic entry describing curr head */ + +#ifndef NDEBUG + /* Bitmap of pushed entries to check for double-push or pop */ + gpr_atm pushed[(INVALID_ENTRY_INDEX+1)/(8*sizeof(gpr_atm))]; +#endif }; gpr_stack_lockfree *gpr_stack_lockfree_create(int entries) { @@ -86,6 +91,9 @@ gpr_stack_lockfree *gpr_stack_lockfree_create(int entries) { /* Clear out all entries */ memset(stack->entries, 0, entries * sizeof(stack->entries[0])); memset(&stack->head, 0, sizeof(stack->head)); +#ifndef NDEBUG + memset(&stack->pushed, 0, sizeof(stack->pushed)); +#endif /* Point the head at reserved dummy entry */ stack->head.contents.index = INVALID_ENTRY_INDEX; @@ -106,6 +114,19 @@ int gpr_stack_lockfree_push(gpr_stack_lockfree *stack, int entry) { /* Also post-increment the aba_ctr */ newhead.contents.aba_ctr = stack->entries[entry].contents.aba_ctr++; +#ifndef NDEBUG + /* Check for double push */ + { + int pushed_index = entry / (8*sizeof(gpr_atm)); + int pushed_bit = entry % (8*sizeof(gpr_atm)); + gpr_atm old_val; + + old_val = gpr_atm_no_barrier_fetch_add(&stack->pushed[pushed_index], + (gpr_atm)(1UL << pushed_bit)); + GPR_ASSERT((old_val & (1UL<<pushed_bit)) == 0); + } +#endif + do { /* Atomically get the existing head value for use */ head.atm = gpr_atm_no_barrier_load(&(stack->head.atm)); @@ -119,6 +140,7 @@ int gpr_stack_lockfree_push(gpr_stack_lockfree *stack, int entry) { int gpr_stack_lockfree_pop(gpr_stack_lockfree *stack) { lockfree_node head; lockfree_node newhead; + do { head.atm = gpr_atm_acq_load(&(stack->head.atm)); if (head.contents.index == INVALID_ENTRY_INDEX) { @@ -128,5 +150,18 @@ int gpr_stack_lockfree_pop(gpr_stack_lockfree *stack) { gpr_atm_no_barrier_load(&(stack->entries[head.contents.index].atm)); } while (!gpr_atm_no_barrier_cas(&(stack->head.atm), head.atm, newhead.atm)); +#ifndef NDEBUG + /* Check for valid pop */ + { + int pushed_index = head.contents.index / (8*sizeof(gpr_atm)); + int pushed_bit = head.contents.index % (8*sizeof(gpr_atm)); + gpr_atm old_val; + + old_val = gpr_atm_no_barrier_fetch_add(&stack->pushed[pushed_index], + -(gpr_atm)(1UL << pushed_bit)); + GPR_ASSERT((old_val & (1UL<<pushed_bit)) != 0); + } +#endif + return head.contents.index; } |