Raise the number of nested readers limit 2^16 and 2^32 on 32 and 64-bits arch.

[urcu.git] / urcu.c

diff --git a/urcu.c b/urcu.c
index 83d2fe4d6d9c367796d123fb05286f8305dfc332..5514b278e4322b0f600a6d3427eab700057dc573 100644 (file)
--- a/urcu.c
+++ b/urcu.c
@@ -19,10 +19,10 @@
 
 pthread_mutex_t urcu_mutex = PTHREAD_MUTEX_INITIALIZER;
 
-/* Global quiescent period parity */
-int urcu_qparity;
+/* Global grace period counter */
+int urcu_gp_ctr;
 
-int __thread urcu_active_readers[2];
+int __thread urcu_active_readers;
 
 /* Thread IDs of registered readers */
 #define INIT_NUM_THREADS 4
@@ -65,11 +65,9 @@ void internal_urcu_unlock(void)
 /*
  * called with urcu_mutex held.
  */
-static int switch_next_urcu_qparity(void)
+static void switch_next_urcu_qparity(void)
 {
-       int old_parity = urcu_qparity;
-       urcu_qparity = 1 - old_parity;
-       return old_parity;
+       urcu_gp_ctr ^= RCU_GP_CTR_BIT;
 }
 
 static void force_mb_all_threads(void)
@@ -101,7 +99,7 @@ static void force_mb_all_threads(void)
        debug_yield_write();
 }
 
-void wait_for_quiescent_state(int parity)
+void wait_for_quiescent_state(void)
 {
        struct reader_data *index;
 
@@ -113,7 +111,7 @@ void wait_for_quiescent_state(int parity)
                /*
                 * BUSY-LOOP.
                 */
-               while (index->urcu_active_readers[parity] != 0)
+               while (rcu_old_gp_ongoing(index->urcu_active_readers))
                        barrier();
        }
        /*
@@ -127,59 +125,23 @@ void wait_for_quiescent_state(int parity)
 
 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();
        debug_yield_write();
-       prev_parity = switch_next_urcu_qparity();
+       switch_next_urcu_qparity();
        debug_yield_write();
 
        /*
         * Wait for previous parity to be empty of readers.
         */
-       wait_for_quiescent_state(prev_parity);
+       wait_for_quiescent_state();
 }
 
 void synchronize_rcu(void)
 {
        debug_yield_write();
        internal_urcu_lock();
-       debug_yield_write();
-       switch_qparity();
-       debug_yield_write();
-       switch_qparity();
-       debug_yield_write();
-       internal_urcu_lock();
-       debug_yield_write();
-}
-
-/*
- * Return old pointer, OK to free, no more reference exist.
- * Called under rcu_write_lock.
- */
-void *urcu_publish_content(void **ptr, void *new)
-{
-       void *oldptr;
-
-       debug_yield_write();
-       internal_urcu_lock();
-       debug_yield_write();
-       /*
-        * We can publish the new pointer before we change the current qparity.
-        * Readers seeing the new pointer while being in the previous qparity
-        * window will make us wait until the end of the quiescent state before
-        * we release the unrelated memory area. However, given we hold the
-        * urcu_mutex, we are making sure that no further garbage collection can
-        * occur until we release the mutex, therefore we guarantee that this
-        * given reader will have completed its execution using the new pointer
-        * when the next quiescent state window will be over.
-        */
-       oldptr = *ptr;
-       debug_yield_write();
-       *ptr = new;
-
        debug_yield_write();
        switch_qparity();
        debug_yield_write();
@@ -187,8 +149,6 @@ void *urcu_publish_content(void **ptr, void *new)
        debug_yield_write();
        internal_urcu_unlock();
        debug_yield_write();
-
-       return oldptr;
 }
 
 void urcu_add_reader(pthread_t id)
@@ -212,7 +172,7 @@ void urcu_add_reader(pthread_t id)
        }
        reader_data[num_readers].tid = id;
        /* reference to the TLS of _this_ reader thread. */
-       reader_data[num_readers].urcu_active_readers = urcu_active_readers;
+       reader_data[num_readers].urcu_active_readers = &urcu_active_readers;
        num_readers++;
 }