rcu: Remove leg of force_quiescent_state() switch statement
The comparisons of rsp->gpnum nad rsp->completed in
rcu_process_dyntick() and force_quiescent_state() can be
replaced by the much more clear rcu_gp_in_progress() predicate
function. After doing this, it becomes clear that the
RCU_SAVE_COMPLETED leg of the force_quiescent_state() function's
switch statement is almost completely a no-op. A small change
to the RCU_SAVE_DYNTICK leg renders it a complete no-op, after
which it can be removed. Doing so also eliminates the forcenow
local variable from force_quiescent_state().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <12626465501781-git-send-email->
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index e497119..6268f37 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1144,6 +1144,7 @@
/*
* Scan the leaf rcu_node structures, processing dyntick state for any that
* have not yet encountered a quiescent state, using the function specified.
+ * The caller must have suppressed start of new grace periods.
*/
static void rcu_process_dyntick(struct rcu_state *rsp,
int (*f)(struct rcu_data *))
@@ -1157,7 +1158,7 @@
rcu_for_each_leaf_node(rsp, rnp) {
mask = 0;
spin_lock_irqsave(&rnp->lock, flags);
- if (rnp->completed != rsp->gpnum - 1) {
+ if (!rcu_gp_in_progress(rsp)) {
spin_unlock_irqrestore(&rnp->lock, flags);
return;
}
@@ -1171,7 +1172,7 @@
if ((rnp->qsmask & bit) != 0 && f(rsp->rda[cpu]))
mask |= bit;
}
- if (mask != 0 && rnp->completed == rsp->gpnum - 1) {
+ if (mask != 0 && rcu_gp_in_progress(rsp)) {
/* rcu_report_qs_rnp() releases rnp->lock. */
rcu_report_qs_rnp(mask, rsp, rnp, flags);
@@ -1189,7 +1190,6 @@
{
unsigned long flags;
struct rcu_node *rnp = rcu_get_root(rsp);
- u8 forcenow;
if (!rcu_gp_in_progress(rsp))
return; /* No grace period in progress, nothing to force. */
@@ -1224,21 +1224,9 @@
/* Record dyntick-idle state. */
rcu_process_dyntick(rsp, dyntick_save_progress_counter);
spin_lock(&rnp->lock); /* irqs already disabled */
- if (!rcu_gp_in_progress(rsp))
- break;
- /* fall into next case. */
-
- case RCU_SAVE_COMPLETED:
-
- /* Update state, record completion counter. */
- forcenow = 0;
- if (rsp->gpnum - 1 == rsp->completed) {
- forcenow = rsp->signaled == RCU_SAVE_COMPLETED;
+ if (rcu_gp_in_progress(rsp))
rsp->signaled = RCU_FORCE_QS;
- }
- if (!forcenow)
- break;
- /* fall into next case. */
+ break;
case RCU_FORCE_QS: