* IBM's contributions to this file may be relicensed under LGPLv2 or later.
*/
+#define _GNU_SOURCE
+#define _LGPL_SOURCE
#include <stdio.h>
#include <pthread.h>
#include <signal.h>
#include <assert.h>
#include <stdlib.h>
+#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <poll.h>
+#include "urcu/wfqueue.h"
+#include "urcu/map/urcu-qsbr.h"
#define BUILD_QSBR_LIB
-#include "urcu-qsbr-static.h"
+#include "urcu/static/urcu-qsbr.h"
+#include "urcu-pointer.h"
+
/* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */
+#undef _LGPL_SOURCE
#include "urcu-qsbr.h"
+#define _LGPL_SOURCE
void __attribute__((destructor)) rcu_exit(void);
static pthread_mutex_t rcu_gp_lock = PTHREAD_MUTEX_INITIALIZER;
-int gp_futex;
+int32_t gp_futex;
/*
* Global grace period counter.
*/
unsigned long rcu_gp_ctr = RCU_GP_ONLINE;
+/*
+ * Active attempts to check for reader Q.S. before calling futex().
+ */
+#define RCU_QS_ACTIVE_ATTEMPTS 100
+
/*
* Written to only by each individual reader. Read by both the reader and the
* writers.
#endif /* !(CAA_BITS_PER_LONG < 64) */
/*
- * Must commit rcu_gp_ctr update to memory before waiting for quiescent
- * state. Failure to do so could result in the writer waiting forever
- * while new readers are always accessing data (no progress). Enforce
- * compiler-order of store to rcu_gp_ctr before load rcu_reader ctr.
+ * Must commit rcu_gp_ctr update to memory before waiting for
+ * quiescent state. Failure to do so could result in the writer
+ * waiting forever while new readers are always accessing data
+ * (no progress). Enforce compiler-order of store to rcu_gp_ctr
+ * before load rcu_reader ctr.
*/
cmm_barrier();
*/
for (;;) {
wait_loops++;
- if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) {
- uatomic_dec(&gp_futex);
+ if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
+ uatomic_set(&gp_futex, -1);
+ /*
+ * Write futex before write waiting (the other side
+ * reads them in the opposite order).
+ */
+ cmm_smp_wmb();
+ cds_list_for_each_entry(index, ®istry, node) {
+ _CMM_STORE_SHARED(index->waiting, 1);
+ }
/* Write futex before read reader_gp */
cmm_smp_mb();
}
-
cds_list_for_each_entry_safe(index, tmp, ®istry, node) {
if (!rcu_gp_ongoing(&index->ctr))
cds_list_move(&index->node, &qsreaders);
}
if (cds_list_empty(®istry)) {
- if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) {
+ if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
/* Read reader_gp before write futex */
cmm_smp_mb();
uatomic_set(&gp_futex, 0);
}
break;
} else {
- if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) {
+ if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
wait_gp();
} else {
#ifndef HAS_INCOHERENT_CACHES
was_online = rcu_reader.ctr;
/* All threads should read qparity before accessing data structure
- * where new ptr points to.
- */
- /* Write new ptr before changing the qparity */
- cmm_smp_mb();
-
- /*
+ * where new ptr points to. In the "then" case, rcu_thread_offline
+ * includes a memory barrier.
+ *
* Mark the writer thread offline to make sure we don't wait for
- * our own quiescent state. This allows using synchronize_rcu() in
- * threads registered as readers.
+ * our own quiescent state. This allows using synchronize_rcu()
+ * in threads registered as readers.
*/
if (was_online)
- CMM_STORE_SHARED(rcu_reader.ctr, 0);
+ rcu_thread_offline();
+ else
+ cmm_smp_mb();
mutex_lock(&rcu_gp_lock);
/*
* Must finish waiting for quiescent state for parity 0 before
- * committing next rcu_gp_ctr update to memory. Failure to do so could
- * result in the writer waiting forever while new readers are always
- * accessing data (no progress). Enforce compiler-order of load
- * rcu_reader ctr before store to rcu_gp_ctr.
+ * committing next rcu_gp_ctr update to memory. Failure to
+ * do so could result in the writer waiting forever while new
+ * readers are always accessing data (no progress). Enforce
+ * compiler-order of load rcu_reader ctr before store to
+ * rcu_gp_ctr.
*/
cmm_barrier();
* freed.
*/
if (was_online)
- _CMM_STORE_SHARED(rcu_reader.ctr, CMM_LOAD_SHARED(rcu_gp_ctr));
- cmm_smp_mb();
+ rcu_thread_online();
+ else
+ cmm_smp_mb();
}
#else /* !(CAA_BITS_PER_LONG < 64) */
void synchronize_rcu(void)
/*
* Mark the writer thread offline to make sure we don't wait for
- * our own quiescent state. This allows using synchronize_rcu() in
- * threads registered as readers.
+ * our own quiescent state. This allows using synchronize_rcu()
+ * in threads registered as readers.
*/
- cmm_smp_mb();
if (was_online)
- CMM_STORE_SHARED(rcu_reader.ctr, 0);
+ rcu_thread_offline();
+ else
+ cmm_smp_mb();
mutex_lock(&rcu_gp_lock);
if (cds_list_empty(®istry))
mutex_unlock(&rcu_gp_lock);
if (was_online)
- _CMM_STORE_SHARED(rcu_reader.ctr, CMM_LOAD_SHARED(rcu_gp_ctr));
- cmm_smp_mb();
+ rcu_thread_online();
+ else
+ cmm_smp_mb();
}
#endif /* !(CAA_BITS_PER_LONG < 64) */
void rcu_exit(void)
{
- assert(cds_list_empty(®istry));
+ /*
+ * Assertion disabled because call_rcu threads are now rcu
+ * readers, and left running at exit.
+ * assert(cds_list_empty(®istry));
+ */
}
+
+#include "urcu-call-rcu-impl.h"
+#include "urcu-defer-impl.h"
projects / urcu.git / blobdiff