rcu: Simplify quiescent-state detection

The current quiescent-state detection algorithm is needlessly
complex.  It records the grace-period number corresponding to
the quiescent state at the time of the quiescent state, which
works, but it seems better to simply erase any record of previous
quiescent states at the time that the CPU notices the new grace
period.  This has the further advantage of removing another piece
of RCU for which lockless reasoning is required.

Therefore, this commit makes this change.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

1 files changed, 0 insertions, 2 deletions

diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 8f0293ce1517..935dd4ca6816 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -246,8 +246,6 @@ struct rcu_data {
                                         /*  in order to detect GP end. */
         unsigned long   gpnum;          /* Highest gp number that this CPU */
                                         /*  is aware of having started. */
-        unsigned long   passed_quiesce_gpnum;
-                                        /* gpnum at time of quiescent state. */
         bool            passed_quiesce; /* User-mode/idle loop etc. */
         bool            qs_pending;     /* Core waits for quiesc state. */
         bool            beenonline;     /* CPU online at least once. */