{
assert(reader_data);
sig_done = 0;
- smp_mb(); /* write sig_done before sending the signals */
+ /*
+ * pthread_kill has a smp_mb(). But beware, we assume it performs
+ * a cache flush on architectures with non-coherent cache. Let's play
+ * safe and don't assume anything : we use smp_mc() to make sure the
+ * cache flush is enforced.
+ * smp_mb(); write sig_done before sending the signals
+ */
+ smp_mc(); /* write sig_done before sending the signals */
pthread_kill(tid, SIGURCU);
/*
* Wait for sighandler (and thus mb()) to execute on every thread.
* BUSY-LOOP.
*/
- while (sig_done < 1)
- smp_rmb(); /* ensure we re-read sig-done */
+ while (LOAD_REMOTE(sig_done) < 1)
+ cpu_relax();
smp_mb(); /* read sig_done before ending the barrier */
}
if (!reader_data)
return;
sig_done = 0;
- smp_mb(); /* write sig_done before sending the signals */
+ /*
+ * pthread_kill has a smp_mb(). But beware, we assume it performs
+ * a cache flush on architectures with non-coherent cache. Let's play
+ * safe and don't assume anything : we use smp_mc() to make sure the
+ * cache flush is enforced.
+ * smp_mb(); write sig_done before sending the signals
+ */
+ smp_mc(); /* write sig_done before sending the signals */
for (index = reader_data; index < reader_data + num_readers; index++)
pthread_kill(index->tid, SIGURCU);
/*
* Wait for sighandler (and thus mb()) to execute on every thread.
* BUSY-LOOP.
*/
- while (sig_done < num_readers)
- smp_rmb(); /* ensure we re-read sig-done */
+ while (LOAD_REMOTE(sig_done) < num_readers)
+ cpu_relax();
smp_mb(); /* read sig_done before ending the barrier */
}
#endif
void synchronize_rcu(void)
{
+ internal_urcu_lock();
+
/* All threads should read qparity before accessing data structure
- * where new ptr points to. */
+ * where new ptr points to. Must be done within internal_urcu_lock
+ * because it iterates on reader threads.*/
/* Write new ptr before changing the qparity */
force_mb_all_threads();
- internal_urcu_lock();
-
switch_next_urcu_qparity(); /* 0 -> 1 */
/*
* waiting forever while new readers are always accessing data (no
* progress).
*/
- smp_mb();
+ smp_mc();
/*
* Wait for previous parity to be empty of readers.
* the writer waiting forever while new readers are always accessing
* data (no progress).
*/
- smp_mb();
+ smp_mc();
switch_next_urcu_qparity(); /* 1 -> 0 */
* waiting forever while new readers are always accessing data (no
* progress).
*/
- smp_mb();
+ smp_mc();
/*
* Wait for previous parity to be empty of readers.
*/
wait_for_quiescent_state(); /* Wait readers in parity 1 */
- internal_urcu_unlock();
-
- /* All threads should finish using the data referred to by old ptr
- * before decrementing their urcu_active_readers count */
/* Finish waiting for reader threads before letting the old ptr being
- * freed. */
+ * freed. Must be done within internal_urcu_lock because it iterates on
+ * reader threads. */
force_mb_all_threads();
+
+ internal_urcu_unlock();
}
void urcu_add_reader(pthread_t id)