From: Pingfan Liu <kernelfans@xxxxxxxxx>
The SRCU_SIZE_* names are not self-explanatory, so this commit therefore
adds comments to the definitions.
Signed-off-by: Pingfan Liu <kernelfans@xxxxxxxxx>
Cc: Lai Jiangshan <jiangshanlai@xxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
Cc: Frederic Weisbecker <frederic@xxxxxxxxxx>
Cc: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: "Zhang, Qiang1" <qiang1.zhang@xxxxxxxxx>
To: rcu@xxxxxxxxxxxxxxx
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
---
include/linux/srcutree.h | 33 +++++++++++++++++++++++----------
1 file changed, 23 insertions(+), 10 deletions(-)
diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h
index 558057b517b7..a6910805f9c5 100644
--- a/include/linux/srcutree.h
+++ b/include/linux/srcutree.h
@@ -92,16 +92,29 @@ struct srcu_struct {
struct lockdep_map dep_map;
};
-/* Values for size state variable (->srcu_size_state). */
-#define SRCU_SIZE_SMALL 0
-#define SRCU_SIZE_ALLOC 1
-#define SRCU_SIZE_WAIT_BARRIER 2
-#define SRCU_SIZE_WAIT_CALL 3
-#define SRCU_SIZE_WAIT_CBS1 4
-#define SRCU_SIZE_WAIT_CBS2 5
-#define SRCU_SIZE_WAIT_CBS3 6
-#define SRCU_SIZE_WAIT_CBS4 7
-#define SRCU_SIZE_BIG 8
+// Values for size state variable (->srcu_size_state). Once the state
+// has been set to SRCU_SIZE_ALLOC, the grace-period code advances through
+// this state machine one step per grace period until the SRCU_SIZE_BIG state
+// is reached. Otherwise, the state machine remains in the SRCU_SIZE_SMALL
+// state indefinitely.
+#define SRCU_SIZE_SMALL 0 // No srcu_node combining tree, ->node == NULL
+#define SRCU_SIZE_ALLOC 1 // An srcu_node tree is being allocated, initialized,
+ // and then referenced by ->node. It will not be used.
+#define SRCU_SIZE_WAIT_BARRIER 2 // The srcu_node tree starts being used by everything
+ // except call_srcu(), especially by srcu_barrier().
+ // By the end of this state, all CPUs and threads
+ // are aware of this tree's existence.
+#define SRCU_SIZE_WAIT_CALL 3 // The srcu_node tree starts being used by call_srcu().
+ // By the end of this state, all of the call_srcu()
+ // invocations that were running on a non-boot CPU
+ // and using the boot CPU's callback queue will have
+ // completed.
+#define SRCU_SIZE_WAIT_CBS1 4 // Don't trust the ->srcu_have_cbs[] grace-period
+#define SRCU_SIZE_WAIT_CBS2 5 // sequence elements or the ->srcu_data_have_cbs[]
+#define SRCU_SIZE_WAIT_CBS3 6 // CPU-bitmask elements until all four elements of
+#define SRCU_SIZE_WAIT_CBS4 7 // each array have been initialized.
+#define SRCU_SIZE_BIG 8 // The srcu_node combining tree is fully initialized
+ // and all aspects of it are being put to use.
/* Values for state variable (bottom bits of ->srcu_gp_seq). */
#define SRCU_STATE_IDLE 0
--
2.40.0.rc1.284.g88254d51c5-goog
