Merge branch 'master' into urcu/ht-shrink

[urcu.git] / urcu-qsbr.c

diff --git a/urcu-qsbr.c b/urcu-qsbr.c
index 1dc99792d7a49f2f6f3614693e34cde239312bfb..553029578a210383df955fb384d6102ad807d51e 100644 (file)
--- a/urcu-qsbr.c
+++ b/urcu-qsbr.c
@@ -39,6 +39,7 @@
 #include "urcu/map/urcu-qsbr.h"
 #define BUILD_QSBR_LIB
 #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
@@ -208,21 +209,17 @@ void synchronize_rcu(void)
        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.
         */
-       if (was_online) {
-               CMM_STORE_SHARED(rcu_reader.ctr, 0);
-               cmm_smp_mb();   /* write rcu_reader.ctr before read futex */
-               wake_up_gp();
-       }
+       if (was_online)
+               rcu_thread_offline();
+       else
+               cmm_smp_mb();
 
        mutex_lock(&rcu_gp_lock);
 
@@ -263,9 +260,9 @@ out:
         * 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)
@@ -279,12 +276,10 @@ void synchronize_rcu(void)
         * 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);
-               cmm_smp_mb();   /* write rcu_reader.ctr before read futex */
-               wake_up_gp();
-       }
+       if (was_online)
+               rcu_thread_offline();
+       else
+               cmm_smp_mb();
 
        mutex_lock(&rcu_gp_lock);
        if (cds_list_empty(&registry))
@@ -294,9 +289,9 @@ out:
        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) */
 
@@ -354,7 +349,11 @@ void rcu_unregister_thread(void)
 
 void rcu_exit(void)
 {
-       assert(cds_list_empty(&registry));
+       /*
+        * Assertion disabled because call_rcu threads are now rcu
+        * readers, and left running at exit.
+        * assert(cds_list_empty(&registry));
+        */
 }
 
 #include "urcu-call-rcu-impl.h"