}
}
-/*
- * called with rcu_gp_lock held.
- */
-static void switch_next_rcu_qparity(void)
-{
- STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR_PHASE);
-}
-
-void wait_for_quiescent_state(void)
+void update_counter_and_wait(void)
{
LIST_HEAD(qsreaders);
int wait_loops = 0;
struct rcu_reader *index, *tmp;
- if (list_empty(®istry))
- return;
+ /* Switch parity: 1 -> 0, 0 -> 1 */
+ STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR_PHASE);
+
+ /*
+ * Must commit qparity update to memory before waiting for other parity
+ * quiescent state. Failure to do so could result in the writer waiting
+ * forever while new readers are always accessing data (no progress).
+ * Ensured by STORE_SHARED and LOAD_SHARED.
+ */
+
+ /*
+ * Adding a smp_mb() which is _not_ formally required, but makes the
+ * model easier to understand. It does not have a big performance impact
+ * anyway, given this is the write-side.
+ */
+ smp_mb();
+
/*
* Wait for each thread rcu_reader.ctr count to become 0.
*/
mutex_lock(&rcu_gp_lock);
- /* Remove old registry elements */
- rcu_gc_registry();
+ if (list_empty(®istry))
+ goto out;
/* All threads should read qparity before accessing data structure
- * where new ptr points to. Must be done within rcu_gp_lock because it
- * iterates on reader threads.*/
+ * where new ptr points to. */
/* Write new ptr before changing the qparity */
smp_mb();
- switch_next_rcu_qparity(); /* 0 -> 1 */
-
- /*
- * Must commit qparity update to memory before waiting for parity
- * 0 quiescent state. Failure to do so could result in the writer
- * waiting forever while new readers are always accessing data (no
- * progress).
- * Ensured by STORE_SHARED and LOAD_SHARED.
- */
-
- /*
- * Adding a smp_mb() which is _not_ formally required, but makes the
- * model easier to understand. It does not have a big performance impact
- * anyway, given this is the write-side.
- */
- smp_mb();
+ /* Remove old registry elements */
+ rcu_gc_registry();
/*
* Wait for previous parity to be empty of readers.
*/
- wait_for_quiescent_state(); /* Wait readers in parity 0 */
-
- /*
- * Must finish waiting for quiescent state for parity 0 before
- * committing qparity update to memory. Failure to do so could result in
- * the writer waiting forever while new readers are always accessing
- * data (no progress).
- * Ensured by STORE_SHARED and LOAD_SHARED.
- */
+ update_counter_and_wait(); /* 0 -> 1, wait readers in parity 0 */
/*
* Adding a smp_mb() which is _not_ formally required, but makes the
*/
smp_mb();
- switch_next_rcu_qparity(); /* 1 -> 0 */
-
/*
- * Must commit qparity update to memory before waiting for parity
- * 1 quiescent state. Failure to do so could result in the writer
- * waiting forever while new readers are always accessing data (no
- * progress).
- * Ensured by STORE_SHARED and LOAD_SHARED.
- */
-
- /*
- * Adding a smp_mb() which is _not_ formally required, but makes the
- * model easier to understand. It does not have a big performance impact
- * anyway, given this is the write-side.
+ * Wait for previous parity to be empty of readers.
*/
- smp_mb();
+ update_counter_and_wait(); /* 1 -> 0, wait readers in parity 1 */
/*
- * Wait for previous parity to be empty of readers.
+ * Finish waiting for reader threads before letting the old ptr being
+ * freed.
*/
- wait_for_quiescent_state(); /* Wait readers in parity 1 */
-
- /* Finish waiting for reader threads before letting the old ptr being
- * freed. Must be done within rcu_gp_lock because it iterates on reader
- * threads. */
smp_mb();
-
+out:
mutex_unlock(&rcu_gp_lock);
ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
assert(!ret);
NULL, NULL, 0);
}
-static void wait_for_quiescent_state(void)
+static void update_counter_and_wait(void)
{
LIST_HEAD(qsreaders);
int wait_loops = 0;
struct rcu_reader *index, *tmp;
- if (list_empty(®istry))
- return;
+#if (BITS_PER_LONG < 64)
+ /* Switch parity: 1 -> 0, 0 -> 1 */
+ STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR);
+#else /* !(BITS_PER_LONG < 64) */
+ /* Increment current G.P. */
+ STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr + RCU_GP_CTR);
+#endif /* !(BITS_PER_LONG < 64) */
+
/*
* Wait for each thread rcu_reader_qs_gp count to become 0.
*/
*/
#if (BITS_PER_LONG < 64)
-/*
- * called with rcu_gp_lock held.
- */
-static void switch_next_rcu_qparity(void)
-{
- STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR);
-}
-
void synchronize_rcu(void)
{
unsigned long was_online;
mutex_lock(&rcu_gp_lock);
- switch_next_rcu_qparity(); /* 0 -> 1 */
-
- /*
- * Must commit qparity update to memory before waiting for parity
- * 0 quiescent state. Failure to do so could result in the writer
- * waiting forever while new readers are always accessing data (no
- * progress).
- * Ensured by STORE_SHARED and LOAD_SHARED.
- */
+ if (list_empty(®istry))
+ goto out;
/*
* Wait for previous parity to be empty of readers.
*/
- wait_for_quiescent_state(); /* Wait readers in parity 0 */
+ update_counter_and_wait(); /* 0 -> 1, wait readers in parity 0 */
/*
* Must finish waiting for quiescent state for parity 0 before
* Ensured by STORE_SHARED and LOAD_SHARED.
*/
- switch_next_rcu_qparity(); /* 1 -> 0 */
-
/*
- * Must commit qparity update to memory before waiting for parity
- * 1 quiescent state. Failure to do so could result in the writer
- * waiting forever while new readers are always accessing data (no
- * progress).
- * Ensured by STORE_SHARED and LOAD_SHARED.
+ * Adding a smp_mb() which is _not_ formally required, but makes the
+ * model easier to understand. It does not have a big performance impact
+ * anyway, given this is the write-side.
*/
+ smp_mb();
/*
* Wait for previous parity to be empty of readers.
*/
- wait_for_quiescent_state(); /* Wait readers in parity 1 */
-
+ update_counter_and_wait(); /* 1 -> 0, wait readers in parity 1 */
+out:
mutex_unlock(&rcu_gp_lock);
/*
STORE_SHARED(rcu_reader.ctr, 0);
mutex_lock(&rcu_gp_lock);
- STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr + RCU_GP_CTR);
- wait_for_quiescent_state();
+ if (list_empty(®istry))
+ goto out;
+ update_counter_and_wait();
+out:
mutex_unlock(&rcu_gp_lock);
if (was_online)
}
}
-/*
- * called with rcu_gp_lock held.
- */
-static void switch_next_rcu_qparity(void)
-{
- STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR_PHASE);
-}
-
#ifdef RCU_MEMBARRIER
static void smp_mb_heavy(void)
{
NULL, NULL, 0);
}
-void wait_for_quiescent_state(void)
+void update_counter_and_wait(void)
{
LIST_HEAD(qsreaders);
int wait_loops = 0;
struct rcu_reader *index, *tmp;
- if (list_empty(®istry))
- return;
+ /* Switch parity: 1 -> 0, 0 -> 1 */
+ STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR_PHASE);
+
+ /*
+ * Must commit qparity update to memory before waiting for other parity
+ * quiescent state. Failure to do so could result in the writer waiting
+ * forever while new readers are always accessing data (no progress).
+ * Ensured by STORE_SHARED and LOAD_SHARED.
+ */
+
+ /*
+ * Adding a smp_mb() which is _not_ formally required, but makes the
+ * model easier to understand. It does not have a big performance impact
+ * anyway, given this is the write-side.
+ */
+ smp_mb();
+
/*
* Wait for each thread rcu_reader.ctr count to become 0.
*/
{
mutex_lock(&rcu_gp_lock);
+ if (list_empty(®istry))
+ goto out;
+
/* All threads should read qparity before accessing data structure
* where new ptr points to. Must be done within rcu_gp_lock because it
* iterates on reader threads.*/
/* Write new ptr before changing the qparity */
smp_mb_heavy();
- switch_next_rcu_qparity(); /* 0 -> 1 */
-
- /*
- * Must commit qparity update to memory before waiting for parity
- * 0 quiescent state. Failure to do so could result in the writer
- * waiting forever while new readers are always accessing data (no
- * progress).
- * Ensured by STORE_SHARED and LOAD_SHARED.
- */
-
- /*
- * Adding a smp_mb() which is _not_ formally required, but makes the
- * model easier to understand. It does not have a big performance impact
- * anyway, given this is the write-side.
- */
- smp_mb();
-
/*
* Wait for previous parity to be empty of readers.
*/
- wait_for_quiescent_state(); /* Wait readers in parity 0 */
+ update_counter_and_wait(); /* 0 -> 1, wait readers in parity 0 */
/*
* Must finish waiting for quiescent state for parity 0 before
*/
smp_mb();
- switch_next_rcu_qparity(); /* 1 -> 0 */
-
- /*
- * Must commit qparity update to memory before waiting for parity
- * 1 quiescent state. Failure to do so could result in the writer
- * waiting forever while new readers are always accessing data (no
- * progress).
- * Ensured by STORE_SHARED and LOAD_SHARED.
- */
-
- /*
- * Adding a smp_mb() which is _not_ formally required, but makes the
- * model easier to understand. It does not have a big performance impact
- * anyway, given this is the write-side.
- */
- smp_mb();
-
/*
* Wait for previous parity to be empty of readers.
*/
- wait_for_quiescent_state(); /* Wait readers in parity 1 */
+ update_counter_and_wait(); /* 1 -> 0, wait readers in parity 1 */
/* Finish waiting for reader threads before letting the old ptr being
* freed. Must be done within rcu_gp_lock because it iterates on reader
* threads. */
smp_mb_heavy();
-
+out:
mutex_unlock(&rcu_gp_lock);
}
projects / urcu.git / commitdiff
