Make extent_dss use C11-style atomics
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92aafb0efe
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@ -18,14 +18,15 @@ const char *dss_prec_names[] = {
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* guarantee that sizeof(dss_prec_t) is the same as sizeof(unsigned), and we use
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* atomic operations to synchronize the setting.
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*/
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static unsigned dss_prec_default = (unsigned)DSS_PREC_DEFAULT;
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static atomic_u_t dss_prec_default = ATOMIC_INIT(
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(unsigned)DSS_PREC_DEFAULT);
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/* Base address of the DSS. */
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static void *dss_base;
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/* Atomic boolean indicating whether the DSS is exhausted. */
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static unsigned dss_exhausted;
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static atomic_b_t dss_exhausted;
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/* Atomic current upper limit on DSS addresses. */
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static void *dss_max;
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static atomic_p_t dss_max;
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/******************************************************************************/
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@ -46,7 +47,7 @@ extent_dss_prec_get(void) {
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if (!have_dss) {
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return dss_prec_disabled;
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}
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ret = (dss_prec_t)atomic_read_u(&dss_prec_default);
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ret = (dss_prec_t)atomic_load_u(&dss_prec_default, ATOMIC_ACQUIRE);
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return ret;
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}
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@ -55,7 +56,7 @@ extent_dss_prec_set(dss_prec_t dss_prec) {
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if (!have_dss) {
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return (dss_prec != dss_prec_disabled);
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}
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atomic_write_u(&dss_prec_default, (unsigned)dss_prec);
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atomic_store_u(&dss_prec_default, (unsigned)dss_prec, ATOMIC_RELEASE);
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return false;
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}
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@ -69,7 +70,7 @@ extent_dss_max_update(void *new_addr) {
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*/
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spin_t spinner = SPIN_INITIALIZER;
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while (true) {
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void *max_prev = atomic_read_p(&dss_max);
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void *max_prev = atomic_load_p(&dss_max, ATOMIC_RELAXED);
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max_cur = extent_dss_sbrk(0);
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if ((uintptr_t)max_prev > (uintptr_t)max_cur) {
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@ -80,7 +81,8 @@ extent_dss_max_update(void *new_addr) {
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spin_adaptive(&spinner);
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continue;
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}
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if (!atomic_cas_p(&dss_max, max_prev, max_cur)) {
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if (atomic_compare_exchange_weak_p(&dss_max, &max_prev,
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max_cur, ATOMIC_ACQ_REL, ATOMIC_RELAXED)) {
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break;
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}
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}
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@ -114,7 +116,7 @@ extent_alloc_dss(tsdn_t *tsdn, arena_t *arena, void *new_addr, size_t size,
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return NULL;
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}
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if (!atomic_read_u(&dss_exhausted)) {
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if (!atomic_load_b(&dss_exhausted, ATOMIC_ACQUIRE)) {
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/*
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* The loop is necessary to recover from races with other
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* threads that are using the DSS for something other than
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@ -167,7 +169,8 @@ extent_alloc_dss(tsdn_t *tsdn, arena_t *arena, void *new_addr, size_t size,
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* DSS while dss_max is greater than the current DSS
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* max reported by sbrk(0).
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*/
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if (atomic_cas_p(&dss_max, max_cur, dss_next)) {
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if (!atomic_compare_exchange_weak_p(&dss_max, &max_cur,
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dss_next, ATOMIC_ACQ_REL, ATOMIC_RELAXED)) {
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continue;
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}
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@ -207,10 +210,12 @@ extent_alloc_dss(tsdn_t *tsdn, arena_t *arena, void *new_addr, size_t size,
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* succeeded since this invocation started, in which
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* case rollback is not necessary.
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*/
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atomic_cas_p(&dss_max, dss_next, max_cur);
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atomic_compare_exchange_strong_p(&dss_max, &dss_next,
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max_cur, ATOMIC_ACQ_REL, ATOMIC_RELAXED);
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if (dss_prev == (void *)-1) {
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/* OOM. */
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atomic_write_u(&dss_exhausted, (unsigned)true);
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atomic_store_b(&dss_exhausted, true,
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ATOMIC_RELEASE);
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goto label_oom;
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}
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}
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@ -230,7 +235,8 @@ bool
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extent_in_dss(void *addr) {
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cassert(have_dss);
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return extent_in_dss_helper(addr, atomic_read_p(&dss_max));
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return extent_in_dss_helper(addr, atomic_load_p(&dss_max,
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ATOMIC_ACQUIRE));
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}
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bool
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@ -244,7 +250,7 @@ extent_dss_mergeable(void *addr_a, void *addr_b) {
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return true;
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}
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max = atomic_read_p(&dss_max);
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max = atomic_load_p(&dss_max, ATOMIC_ACQUIRE);
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return (extent_in_dss_helper(addr_a, max) ==
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extent_in_dss_helper(addr_b, max));
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}
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@ -254,8 +260,8 @@ extent_dss_boot(void) {
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cassert(have_dss);
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dss_base = extent_dss_sbrk(0);
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dss_exhausted = (unsigned)(dss_base == (void *)-1);
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dss_max = dss_base;
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atomic_store_b(&dss_exhausted, dss_base == (void *)-1, ATOMIC_RELAXED);
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atomic_store_p(&dss_max, dss_base, ATOMIC_RELAXED);
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}
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/******************************************************************************/
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