From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Sat, 9 Jul 2011 20:34:29 +0000 (-0400)
Subject: rculfhash: document flags
X-Git-Tag: v0.7.0~43^2~201
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=d95bd16028d250211f2e65cd583e422f4ecdf7d0;p=userspace-rcu.git

rculfhash: document flags

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/rculfhash.c b/rculfhash.c
index 55f56ce..e814717 100644
--- a/rculfhash.c
+++ b/rculfhash.c
@@ -53,6 +53,11 @@
 #define max(a, b)	((a) > (b) ? (a) : (b))
 #endif
 
+/*
+ * The removed flag needs to be updated atomically with the pointer.
+ * The dummy flag does not require to be updated atomically with the
+ * pointer, but it is added as a pointer low bit flag to save space.
+ */
 #define REMOVED_FLAG		(1UL << 0)
 #define DUMMY_FLAG		(1UL << 1)
 #define FLAGS_MASK		((1UL << 2) - 1)
diff --git a/urcu/rculfhash.h b/urcu/rculfhash.h
index 5c5d4eb..b98b493 100644
--- a/urcu/rculfhash.h
+++ b/urcu/rculfhash.h
@@ -9,7 +9,7 @@ extern "C" {
 #endif
 
 struct _rcu_ht_node {
-	struct rcu_ht_node *next;
+	struct rcu_ht_node *next;	/* ptr | DUMMY_FLAG | REMOVED_FLAG */
 	unsigned long reverse_hash;
 };