+/*
+ * urcu.c
+ *
+ * Userspace RCU library
+ *
+ * Copyright February 2009 - Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
+ *
+ * Distributed under GPLv2
+ */
+
#include <stdio.h>
#include <pthread.h>
#include <signal.h>
static int num_readers, alloc_readers;
static int sig_done;
+void rcu_write_lock(void)
+{
+ int ret;
+ ret = pthread_mutex_lock(&urcu_mutex);
+ if (ret) {
+ perror("Error in pthread mutex lock");
+ exit(-1);
+ }
+}
+
+void rcu_write_unlock(void)
+{
+ int ret;
+
+ ret = pthread_mutex_unlock(&urcu_mutex);
+ if (ret) {
+ perror("Error in pthread mutex unlock");
+ exit(-1);
+ }
+}
+
/*
* called with urcu_mutex held.
*/
/*
* BUSY-LOOP.
*/
- while (*index->urcu_active_readers != 0)
+ while (index->urcu_active_readers[parity] != 0)
barrier();
}
/*
force_mb_all_threads();
}
+static void switch_qparity(void)
+{
+ int prev_parity;
+
+ /* All threads should read qparity before accessing data structure. */
+ /* Write ptr before changing the qparity */
+ force_mb_all_threads();
+ prev_parity = switch_next_urcu_qparity();
+
+ /*
+ * Wait for previous parity to be empty of readers.
+ */
+ wait_for_quiescent_state(prev_parity);
+}
+
+void synchronize_rcu(void)
+{
+ rcu_write_lock();
+ switch_qparity();
+ switch_qparity();
+ rcu_write_unlock();
+}
+
/*
* Return old pointer, OK to free, no more reference exist.
+ * Called under rcu_write_lock.
*/
void *urcu_publish_content(void **ptr, void *new)
{
- int ret, prev_parity;
void *oldptr;
- ret = pthread_mutex_lock(&urcu_mutex);
- if (ret) {
- perror("Error in pthread mutex lock");
- exit(-1);
- }
-
/*
* We can publish the new pointer before we change the current qparity.
* Readers seeing the new pointer while being in the previous qparity
*/
oldptr = *ptr;
*ptr = new;
- wmb(); /* Write ptr before changing the qparity */
- /* All threads should read qparity before ptr */
- force_mb_all_threads();
- prev_parity = switch_next_urcu_qparity();
- /*
- * Wait for previous parity to be empty of readers.
- */
- wait_for_quiescent_state(prev_parity);
- /*
- * Deleting old data is ok !
- */
-
- ret = pthread_mutex_unlock(&urcu_mutex);
- if (ret) {
- perror("Error in pthread mutex lock");
- exit(-1);
- }
+ switch_qparity();
+ switch_qparity();
+
return oldptr;
}
assert(reader_data != NULL);
for (index = reader_data; index < reader_data + num_readers; index++) {
- if (index->tid == id) {
+ if (pthread_equal(index->tid, id)) {
memcpy(index, &reader_data[num_readers - 1],
sizeof(struct reader_data));
reader_data[num_readers - 1].tid = 0;
void urcu_register_thread(void)
{
- pthread_t self = pthread_self();
- int ret;
-
- ret = pthread_mutex_lock(&urcu_mutex);
- if (ret) {
- perror("Error in pthread mutex lock");
- exit(-1);
- }
-
- urcu_add_reader(self);
-
-
- ret = pthread_mutex_unlock(&urcu_mutex);
- if (ret) {
- perror("Error in pthread mutex unlock");
- exit(-1);
- }
+ rcu_write_lock();
+ urcu_add_reader(pthread_self());
+ rcu_write_unlock();
}
void urcu_unregister_thread(void)
{
- pthread_t self = pthread_self();
- int ret;
-
- ret = pthread_mutex_lock(&urcu_mutex);
- if (ret) {
- perror("Error in pthread mutex lock");
- exit(-1);
- }
-
- urcu_remove_reader(self);
-
- ret = pthread_mutex_unlock(&urcu_mutex);
- if (ret) {
- perror("Error in pthread mutex unlock");
- exit(-1);
- }
-
+ rcu_write_lock();
+ urcu_remove_reader(pthread_self());
+ rcu_write_unlock();
}
void sigurcu_handler(int signo, siginfo_t *siginfo, void *context)