[PATCH tip/core/rcu 7/9] nohz_full: Add full-system-idle arguments to API

Paul E. McKenney
2013-08-18T01:51:42Z

From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>

This commit adds an isidle and jiffies argument to force_qs_rnp(),
dyntick_save_progress_counter(), and rcu_implicit_dynticks_qs() to enable
RCU's force-quiescent-state process to check for full-system idle.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
[ paulmck: Use true and false for boolean constants per Lai Jiangshan. ]
---
kernel/rcutree.c | 23 ++++++++++++++++-------
1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index b0d2cc3..f1a0b05 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -246,7 +246,9 @@ module_param(jiffies_till_next_fqs, ulong, 0644);

static void rcu_start_gp_advanced(struct rcu_state *rsp, struct rcu_node *rnp,
struct rcu_data *rdp);
-static void force_qs_rnp(struct rcu_state *rsp, int (*f)(struct rcu_data *));
+static void force_qs_rnp(struct rcu_state *rsp,
+ int (*f)(struct rcu_data *, bool *, unsigned long *),
+ bool *isidle, unsigned long *maxj);
static void force_quiescent_state(struct rcu_state *rsp);
static int rcu_pending(int cpu);

@@ -727,7 +729,8 @@ static int rcu_is_cpu_rrupt_from_idle(void)
* credit them with an implicit quiescent state. Return 1 if this CPU
* is in dynticks idle mode, which is an extended quiescent state.
*/
-static int dyntick_save_progress_counter(struct rcu_data *rdp)
+static int dyntick_save_progress_counter(struct rcu_data *rdp,
+ bool *isidle, unsigned long *maxj)
{
rdp->dynticks_snap = atomic_add_return(0, &rdp->dynticks->dynticks);
return (rdp->dynticks_snap & 0x1) == 0;
@@ -739,7 +742,8 @@ static int dyntick_save_progress_counter(struct rcu_data *rdp)
* idle state since the last call to dyntick_save_progress_counter()
* for this same CPU, or by virtue of having been offline.
*/
-static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
+static int rcu_implicit_dynticks_qs(struct rcu_data *rdp,
+ bool *isidle, unsigned long *maxj)
{
unsigned int curr;
unsigned int snap;
@@ -1361,16 +1365,19 @@ static int rcu_gp_init(struct rcu_state *rsp)
int rcu_gp_fqs(struct rcu_state *rsp, int fqs_state_in)
{
int fqs_state = fqs_state_in;
+ bool isidle = false;
+ unsigned long maxj;
struct rcu_node *rnp = rcu_get_root(rsp);

rsp->n_force_qs++;
if (fqs_state == RCU_SAVE_DYNTICK) {
/* Collect dyntick-idle snapshots. */
- force_qs_rnp(rsp, dyntick_save_progress_counter);
+ force_qs_rnp(rsp, dyntick_save_progress_counter,
+ &isidle, &maxj);
fqs_state = RCU_FORCE_QS;
} else {
/* Handle dyntick-idle and offline CPUs. */
- force_qs_rnp(rsp, rcu_implicit_dynticks_qs);
+ force_qs_rnp(rsp, rcu_implicit_dynticks_qs, &isidle, &maxj);
}
/* Clear flag to prevent immediate re-entry. */
if (ACCESS_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) {
@@ -2069,7 +2076,9 @@ void rcu_check_callbacks(int cpu, int user)
*
* The caller must have suppressed start of new grace periods.
*/
-static void force_qs_rnp(struct rcu_state *rsp, int (*f)(struct rcu_data *))
+static void force_qs_rnp(struct rcu_state *rsp,
+ int (*f)(struct rcu_data *, bool *, unsigned long *),
+ bool *isidle, unsigned long *maxj)
{
unsigned long bit;
int cpu;
@@ -2093,7 +2102,7 @@ static void force_qs_rnp(struct rcu_state *rsp, int (*f)(struct rcu_data *))
bit = 1;
for (; cpu <= rnp->grphi; cpu++, bit <<= 1) {
if ((rnp->qsmask & bit) != 0 &&
- f(per_cpu_ptr(rsp->rda, cpu)))
+ f(per_cpu_ptr(rsp->rda, cpu), isidle, maxj))
mask |= bit;
}
if (mask != 0) {
--
1.8.1.5