rcu: Finish folding ->fqs_state into ->gp_state
Commit commit 4cdfc175c25c89ee ("rcu: Move quiescent-state forcing
into kthread") started the process of folding the old ->fqs_state into
->gp_state, but did not complete it. This situation does not cause
any malfunction, but can result in extremely confusing trace output.
This commit completes this task of eliminating ->fqs_state in favor
of ->gp_state.
The old ->fqs_state was also used to decide when to collect dyntick-idle
snapshots. For this purpose, we add a boolean variable into the kthread,
which is set on the first call to rcu_gp_fqs() for a given grace period
and clear otherwise.
Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 0c33c82..be6d1e8 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -412,13 +412,6 @@
struct rcu_state *rsp;
};
-/* Values for fqs_state field in struct rcu_state. */
-#define RCU_GP_IDLE 0 /* No grace period in progress. */
-#define RCU_GP_INIT 1 /* Grace period being initialized. */
-#define RCU_SAVE_DYNTICK 2 /* Need to scan dyntick state. */
-#define RCU_FORCE_QS 3 /* Need to force quiescent state. */
-#define RCU_SIGNAL_INIT RCU_SAVE_DYNTICK
-
/* Values for nocb_defer_wakeup field in struct rcu_data. */
#define RCU_NOGP_WAKE_NOT 0
#define RCU_NOGP_WAKE 1
@@ -468,9 +461,8 @@
/* The following fields are guarded by the root rcu_node's lock. */
- u8 fqs_state ____cacheline_internodealigned_in_smp;
- /* Force QS state. */
- u8 boost; /* Subject to priority boost. */
+ u8 boost ____cacheline_internodealigned_in_smp;
+ /* Subject to priority boost. */
unsigned long gpnum; /* Current gp number. */
unsigned long completed; /* # of last completed gp. */
struct task_struct *gp_kthread; /* Task for grace periods. */
@@ -538,7 +530,7 @@
#define RCU_GP_FLAG_FQS 0x2 /* Need grace-period quiescent-state forcing. */
/* Values for rcu_state structure's gp_flags field. */
-#define RCU_GP_WAIT_INIT 0 /* Initial state. */
+#define RCU_GP_IDLE 0 /* Initial state and no GP in progress. */
#define RCU_GP_WAIT_GPS 1 /* Wait for grace-period start. */
#define RCU_GP_DONE_GPS 2 /* Wait done for grace-period start. */
#define RCU_GP_WAIT_FQS 3 /* Wait for force-quiescent-state time. */