}
#ifdef DEBUG_FULL_MB
+static void force_mb_single_thread(pthread_t tid)
+{
+ smp_mb();
+}
+
static void force_mb_all_threads(void)
{
smp_mb();
}
#else
+
+static void force_mb_single_thread(pthread_t tid)
+{
+ assert(reader_data);
+ sig_done = 0;
+ smp_mb(); /* 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 */
+ smp_mb(); /* read sig_done before ending the barrier */
+}
+
static void force_mb_all_threads(void)
{
struct reader_data *index;
* BUSY-LOOP.
*/
while (sig_done < num_readers)
- barrier();
+ smp_rmb(); /* ensure we re-read sig-done */
smp_mb(); /* read sig_done before ending the barrier */
}
#endif
if (!reader_data)
return;
- /* Wait for each thread urcu_active_readers count to become 0.
+ /*
+ * Wait for each thread urcu_active_readers count to become 0.
*/
for (index = reader_data; index < reader_data + num_readers; index++) {
+ int wait_loops = 0;
/*
- * BUSY-LOOP.
+ * BUSY-LOOP. Force the reader thread to commit its
+ * urcu_active_readers update to memory if we wait for too long.
*/
- while (rcu_old_gp_ongoing(index->urcu_active_readers))
- barrier();
+ while (rcu_old_gp_ongoing(index->urcu_active_readers)) {
+ if (wait_loops++ == KICK_READER_LOOPS) {
+ force_mb_single_thread(index->tid);
+ wait_loops = 0;
+ }
+ }
}
}
#ifndef DEBUG_FULL_MB
void sigurcu_handler(int signo, siginfo_t *siginfo, void *context)
{
+ /*
+ * Executing this smp_mb() is the only purpose of this signal handler.
+ * It punctually promotes barrier() into smp_mb() on every thread it is
+ * executed on.
+ */
smp_mb();
atomic_inc(&sig_done);
}