rcu/nocb: Turn enabled/offload states into a common flag

This commit gathers the rcu_segcblist ->enabled and ->offloaded property
field into a single ->flags bitmask to avoid further proliferation of
individual u8 fields in the structure.  This change prepares for the
state formerly known as ->offloaded state to be modified at runtime.

Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Inspired-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

diff --git a/include/linux/rcu_segcblist.h b/include/linux/rcu_segcblist.h
index 6c01f09a6456c5c97685f8540112eb3956ca165f..4714b0263c76e997fb31e7a0d0f2e11ed41044a9 100644 (file)
--- a/include/linux/rcu_segcblist.h
+++ b/include/linux/rcu_segcblist.h
@@ -63,6 +63,9 @@ struct rcu_cblist {
 #define RCU_NEXT_TAIL          3
 #define RCU_CBLIST_NSEGS       4
 
+#define SEGCBLIST_ENABLED      BIT(0)
+#define SEGCBLIST_OFFLOADED    BIT(1)
+
 struct rcu_segcblist {
        struct rcu_head *head;
        struct rcu_head **tails[RCU_CBLIST_NSEGS];
@@ -73,8 +76,7 @@ struct rcu_segcblist {
        long len;
 #endif
        long seglen[RCU_CBLIST_NSEGS];
-       u8 enabled;
-       u8 offloaded;
+       u8 flags;
 };
 
 #define RCU_SEGCBLIST_INITIALIZER(n) \

diff --git a/kernel/rcu/rcu_segcblist.c b/kernel/rcu/rcu_segcblist.c
index 89e0dff890bf78297f6611181fc0a5201fa353ab..934945d72ca59d85dcaa28a8d1647ae84f584bfe 100644 (file)
--- a/kernel/rcu/rcu_segcblist.c
+++ b/kernel/rcu/rcu_segcblist.c
@@ -246,7 +246,7 @@ void rcu_segcblist_init(struct rcu_segcblist *rsclp)
                rcu_segcblist_set_seglen(rsclp, i, 0);
        }
        rcu_segcblist_set_len(rsclp, 0);
-       rsclp->enabled = 1;
+       rcu_segcblist_set_flags(rsclp, SEGCBLIST_ENABLED);
 }
 
 /*
@@ -257,7 +257,7 @@ void rcu_segcblist_disable(struct rcu_segcblist *rsclp)
 {
        WARN_ON_ONCE(!rcu_segcblist_empty(rsclp));
        WARN_ON_ONCE(rcu_segcblist_n_cbs(rsclp));
-       rsclp->enabled = 0;
+       rcu_segcblist_clear_flags(rsclp, SEGCBLIST_ENABLED);
 }
 
 /*
@@ -266,7 +266,7 @@ void rcu_segcblist_disable(struct rcu_segcblist *rsclp)
  */
 void rcu_segcblist_offload(struct rcu_segcblist *rsclp)
 {
-       rsclp->offloaded = 1;
+       rcu_segcblist_set_flags(rsclp, SEGCBLIST_OFFLOADED);
 }
 
 /*

diff --git a/kernel/rcu/rcu_segcblist.h b/kernel/rcu/rcu_segcblist.h
index 18e101de8747b360bf60489535b2add7575e1321..ff372db09f8b132490c3c91f52af27c6f2b658de 100644 (file)
--- a/kernel/rcu/rcu_segcblist.h
+++ b/kernel/rcu/rcu_segcblist.h
@@ -53,19 +53,38 @@ static inline long rcu_segcblist_n_cbs(struct rcu_segcblist *rsclp)
 #endif
 }
 
+static inline void rcu_segcblist_set_flags(struct rcu_segcblist *rsclp,
+                                          int flags)
+{
+       rsclp->flags |= flags;
+}
+
+static inline void rcu_segcblist_clear_flags(struct rcu_segcblist *rsclp,
+                                            int flags)
+{
+       rsclp->flags &= ~flags;
+}
+
+static inline bool rcu_segcblist_test_flags(struct rcu_segcblist *rsclp,
+                                           int flags)
+{
+       return READ_ONCE(rsclp->flags) & flags;
+}
+
 /*
  * Is the specified rcu_segcblist enabled, for example, not corresponding
  * to an offline CPU?
  */
 static inline bool rcu_segcblist_is_enabled(struct rcu_segcblist *rsclp)
 {
-       return rsclp->enabled;
+       return rcu_segcblist_test_flags(rsclp, SEGCBLIST_ENABLED);
 }
 
 /* Is the specified rcu_segcblist offloaded?  */
 static inline bool rcu_segcblist_is_offloaded(struct rcu_segcblist *rsclp)
 {
-       return IS_ENABLED(CONFIG_RCU_NOCB_CPU) && rsclp->offloaded;
+       return IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&
+               rcu_segcblist_test_flags(rsclp, SEGCBLIST_OFFLOADED);
 }
 
 /*