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Replace non-loop usage of atomic_compare_exchange_weak with strong variant

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While testing BIND 9 on arm64 8+ core machine, it was discovered that
the weak variants in fact does spuriously fail, we haven't observed that
on other architectures.

This commit replaces all non-loop usage of atomic_compare_exchange_weak
with atomic_compare_exchange_strong.
This commit is contained in:
Ondřej Surý
2020-02-12 09:17:55 +01:00
parent fa68a0d869
commit 4cf275ba8a
2 changed files with 36 additions and 50 deletions
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34
lib/isc/app.c
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@@ -228,8 +228,6 @@ isc_result_t
isc_app_ctxrun(isc_appctx_t *ctx) {
isc_event_t *event, *next_event;
isc_task_t *task;
bool exp_false = false;
bool exp_true = true;
REQUIRE(VALID_APPCTX(ctx));
@@ -237,8 +235,8 @@ isc_app_ctxrun(isc_appctx_t *ctx) {
REQUIRE(main_thread == GetCurrentThread());
#endif /* ifdef WIN32 */
if (atomic_compare_exchange_weak_acq_rel(&ctx->running, &exp_false,
true) == true)
if (atomic_compare_exchange_strong_acq_rel(
&ctx->running, &(bool){ false }, true) == true)
{
/*
* Post any on-run events (in FIFO order).
@@ -344,9 +342,9 @@ isc_app_ctxrun(isc_appctx_t *ctx) {
}
}
#endif /* WIN32 */
exp_true = true;
if (atomic_compare_exchange_weak_acq_rel(&ctx->want_reload,
&exp_true, false)) {
if (atomic_compare_exchange_strong_acq_rel(
&ctx->want_reload, &(bool){ true }, false))
{
return (ISC_R_RELOAD);
}
@@ -363,10 +361,9 @@ isc_app_ctxrun(isc_appctx_t *ctx) {
isc_result_t
isc_app_run(void) {
isc_result_t result;
bool exp_false = false;
REQUIRE(atomic_compare_exchange_weak_acq_rel(&is_running, &exp_false,
true) == true);
REQUIRE(atomic_compare_exchange_strong_acq_rel(
&is_running, &(bool){ false }, true) == true);
result = isc_app_ctxrun(&isc_g_appctx);
atomic_store_release(&is_running, false);
@@ -380,8 +377,6 @@ isc_app_isrunning() {
void
isc_app_ctxshutdown(isc_appctx_t *ctx) {
bool exp_false = false;
REQUIRE(VALID_APPCTX(ctx));
REQUIRE(atomic_load_acquire(&ctx->running));
@@ -389,8 +384,8 @@ isc_app_ctxshutdown(isc_appctx_t *ctx) {
/* If ctx->shutdown_requested == true, we are already shutting
* down and we want to just bail out.
*/
if (atomic_compare_exchange_weak_acq_rel(&ctx->shutdown_requested,
&exp_false, true))
if (atomic_compare_exchange_strong_acq_rel(&ctx->shutdown_requested,
&(bool){ false }, true))
{
#ifdef WIN32
SetEvent(ctx->hEvents[SHUTDOWN_EVENT]);
@@ -480,10 +475,9 @@ isc_app_finish(void) {
void
isc_app_block(void) {
bool exp_false = false;
REQUIRE(atomic_load_acquire(&isc_g_appctx.running));
REQUIRE(atomic_compare_exchange_weak_acq_rel(&isc_g_appctx.blocked,
&exp_false, true));
REQUIRE(atomic_compare_exchange_strong_acq_rel(&isc_g_appctx.blocked,
&(bool){ false }, true));
#ifdef WIN32
blockedthread = GetCurrentThread();
@@ -499,11 +493,9 @@ isc_app_block(void) {
void
isc_app_unblock(void) {
bool exp_true = true;
REQUIRE(atomic_load_acquire(&isc_g_appctx.running));
REQUIRE(atomic_compare_exchange_weak_acq_rel(&isc_g_appctx.blocked,
&exp_true, false));
REQUIRE(atomic_compare_exchange_strong_acq_rel(&isc_g_appctx.blocked,
&(bool){ true }, false));
#ifdef WIN32
REQUIRE(blockedthread == GetCurrentThread());