Fix: deadlock when thread join is issued in read-side C.S.

[userspace-rcu.git] / urcu-call-rcu-impl.h

diff --git a/urcu-call-rcu-impl.h b/urcu-call-rcu-impl.h
index 0cc2ba239d4f2c4a6f0b898c76762027c522cbb1..c0298d24b6a732ba7979fa3aa740b4085e1ccb45 100644 (file)
--- a/urcu-call-rcu-impl.h
+++ b/urcu-call-rcu-impl.h
@@ -81,7 +81,23 @@ static struct call_rcu_data *default_call_rcu_data;
  * CPUs rather than only to specific threads.
  */
 
-#if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF)
+#ifdef HAVE_SCHED_GETCPU
+
+static int urcu_sched_getcpu(void)
+{
+       return sched_getcpu();
+}
+
+#else /* #ifdef HAVE_SCHED_GETCPU */
+
+static int urcu_sched_getcpu(void)
+{
+       return -1;
+}
+
+#endif /* #else #ifdef HAVE_SCHED_GETCPU */
+
+#if defined(HAVE_SYSCONF) && defined(HAVE_SCHED_GETCPU)
 
 /*
  * Pointer to array of pointers to per-CPU call_rcu_data structures
@@ -124,7 +140,7 @@ static void alloc_cpu_call_rcu_data(void)
        }
 }
 
-#else /* #if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF) */
+#else /* #if defined(HAVE_SYSCONF) && defined(HAVE_SCHED_GETCPU) */
 
 /*
  * per_cpu_call_rcu_data should be constant, but some functions below, used both
@@ -142,12 +158,7 @@ static void alloc_cpu_call_rcu_data(void)
 {
 }
 
-static int sched_getcpu(void)
-{
-       return -1;
-}
-
-#endif /* #else #if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF) */
+#endif /* #else #if defined(HAVE_SYSCONF) && defined(HAVE_SCHED_GETCPU) */
 
 /* Acquire the specified pthread mutex. */
 
@@ -256,6 +267,8 @@ static void *call_rcu_thread(void *arg)
                        uatomic_or(&crdp->flags, URCU_CALL_RCU_PAUSED);
                        while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_PAUSE) != 0)
                                poll(NULL, 0, 1);
+                       uatomic_and(&crdp->flags, ~URCU_CALL_RCU_PAUSED);
+                       cmm_smp_mb__after_uatomic_and();
                        rcu_register_thread();
                }
 
@@ -350,7 +363,7 @@ static void call_rcu_data_init(struct call_rcu_data **crdpp,
  * Return a pointer to the call_rcu_data structure for the specified
  * CPU, returning NULL if there is none.  We cannot automatically
  * created it because the platform we are running on might not define
- * sched_getcpu().
+ * urcu_sched_getcpu().
  *
  * The call to this function and use of the returned call_rcu_data
  * should be protected by RCU read-side lock.
@@ -492,7 +505,7 @@ struct call_rcu_data *get_call_rcu_data(void)
                return URCU_TLS(thread_call_rcu_data);
 
        if (maxcpus > 0) {
-               crd = get_cpu_call_rcu_data(sched_getcpu());
+               crd = get_cpu_call_rcu_data(urcu_sched_getcpu());
                if (crd)
                        return crd;
        }
@@ -752,6 +765,10 @@ void call_rcu_after_fork_parent(void)
 
        cds_list_for_each_entry(crdp, &call_rcu_data_list, list)
                uatomic_and(&crdp->flags, ~URCU_CALL_RCU_PAUSE);
+       cds_list_for_each_entry(crdp, &call_rcu_data_list, list) {
+               while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_PAUSED) != 0)
+                       poll(NULL, 0, 1);
+       }
        call_rcu_unlock(&call_rcu_mutex);
 }