From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Date: Mon, 9 Feb 2009 18:52:41 +0000 (-0500)
Subject: Fix int->long and keep a reader count of 1 in the global GP variable
X-Git-Tag: v0.1~300
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=128166c908bfaa915c76e060522abd20241ac69c;p=userspace-rcu.git

Fix int->long and keep a reader count of 1 in the global GP variable

- Forgot a few migration from int to long
- Accelerate fast path by reading a GP variable which already has 1 reader
  count. This saves an increment in the fast path.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
---

diff --git a/urcu.c b/urcu.c
index 53c7f37..d4a0684 100644
--- a/urcu.c
+++ b/urcu.c
@@ -19,8 +19,12 @@
 
 pthread_mutex_t urcu_mutex = PTHREAD_MUTEX_INITIALIZER;
 
-/* Global grace period counter */
-long urcu_gp_ctr;
+/*
+ * Global grace period counter.
+ * Contains the current RCU_GP_CTR_BIT.
+ * Also has a RCU_GP_CTR_BIT of 1, to accelerate the reader fast path.
+ */
+long urcu_gp_ctr = RCU_GP_COUNT;
 
 long __thread urcu_active_readers;
 
@@ -29,7 +33,7 @@ long __thread urcu_active_readers;
 
 struct reader_data {
 	pthread_t tid;
-	int *urcu_active_readers;
+	long *urcu_active_readers;
 };
 
 #ifdef DEBUG_YIELD
diff --git a/urcu.h b/urcu.h
index 444d9cd..9e9fea2 100644
--- a/urcu.h
+++ b/urcu.h
@@ -179,7 +179,7 @@ extern long urcu_gp_ctr;
 
 extern long __thread urcu_active_readers;
 
-static inline int rcu_old_gp_ongoing(int *value)
+static inline int rcu_old_gp_ongoing(long *value)
 {
 	long v;
 
@@ -200,7 +200,7 @@ static inline void rcu_read_lock(void)
 	tmp = urcu_active_readers;
 	debug_yield_read();
 	if (likely(!(tmp & RCU_GP_CTR_NEST_MASK)))
-		urcu_active_readers = urcu_gp_ctr + RCU_GP_COUNT;
+		urcu_active_readers = urcu_gp_ctr;
 	else
 		urcu_active_readers = tmp + RCU_GP_COUNT;
 	debug_yield_read();