[RFC v2 14/18] rcu: Store first_gp_fqs into struct rcu_state
From: Petr Mladek <pmladek@suse.com>
Date: 2015-09-21 13:08:00
Also in:
linux-api, lkml
Subsystem:
read-copy update (rcu), the rest · Maintainers:
"Paul E. McKenney", Frederic Weisbecker, Neeraj Upadhyay, Joel Fernandes, Josh Triplett, Boqun Feng, Uladzislau Rezki, Linus Torvalds
We are going to try split the rcu kthread into few kthread works. We will not stay in the funciton all the time and "first_gp_fqs" variable will not preserve the state. Let's store it into struct rcu_state. Note that this change is needed only when the split into more kthread works is accepted. The patch does not change the existing behavior. Signed-off-by: Petr Mladek <pmladek@suse.com> --- kernel/rcu/tree.c | 11 +++++------ kernel/rcu/tree.h | 2 ++ 2 files changed, 7 insertions(+), 6 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 5413d87a67c6..5a3e70a21df8 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c@@ -1927,7 +1927,7 @@ static bool rcu_gp_fqs_check_wake(struct rcu_state *rsp, int *gfp) /* * Do one round of quiescent-state forcing. */ -static void rcu_gp_fqs(struct rcu_state *rsp, bool first_time) +static void rcu_gp_fqs(struct rcu_state *rsp) { bool isidle = false; unsigned long maxj;
@@ -1935,7 +1935,7 @@ static void rcu_gp_fqs(struct rcu_state *rsp, bool first_time) WRITE_ONCE(rsp->gp_activity, jiffies); rsp->n_force_qs++; - if (first_time) { + if (rsp->first_gp_fqs) { /* Collect dyntick-idle snapshots. */ if (is_sysidle_rcu_state(rsp)) { isidle = true;
@@ -1944,6 +1944,7 @@ static void rcu_gp_fqs(struct rcu_state *rsp, bool first_time) force_qs_rnp(rsp, dyntick_save_progress_counter, &isidle, &maxj); rcu_sysidle_report_gp(rsp, isidle, maxj); + rsp->first_gp_fqs = false; } else { /* Handle dyntick-idle and offline CPUs. */ isidle = true;
@@ -2038,7 +2039,6 @@ static void rcu_gp_cleanup(struct rcu_state *rsp) */ static int __noreturn rcu_gp_kthread(void *arg) { - bool first_gp_fqs; int gf; unsigned long j; int ret;
@@ -2070,7 +2070,7 @@ static int __noreturn rcu_gp_kthread(void *arg) } /* Handle quiescent-state forcing. */ - first_gp_fqs = true; + rsp->first_gp_fqs = true; j = jiffies_till_first_fqs; if (j > HZ) { j = HZ;
@@ -2098,8 +2098,7 @@ static int __noreturn rcu_gp_kthread(void *arg) trace_rcu_grace_period(rsp->name, READ_ONCE(rsp->gpnum), TPS("fqsstart")); - rcu_gp_fqs(rsp, first_gp_fqs); - first_gp_fqs = false; + rcu_gp_fqs(rsp); trace_rcu_grace_period(rsp->name, READ_ONCE(rsp->gpnum), TPS("fqsend"));
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index de370b611837..f16578a5eefe 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h@@ -470,6 +470,8 @@ struct rcu_state { wait_queue_head_t gp_wq; /* Where GP task waits. */ short gp_flags; /* Commands for GP task. */ short gp_state; /* GP kthread sleep state. */ + bool first_gp_fqs; /* Do we force QS for */ + /* the first time? */ /* End of fields guarded by root rcu_node's lock. */
--
1.8.5.6
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