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Message-Id: <20180829223854.4055-49-paulmck@linux.vnet.ibm.com>
Date: Wed, 29 Aug 2018 15:38:51 -0700
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To: linux-kernel@...r.kernel.org
Cc: mingo@...nel.org, jiangshanlai@...il.com, dipankar@...ibm.com,
akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
fweisbec@...il.com, oleg@...hat.com, joel@...lfernandes.org,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 49/52] rcu: Eliminate quiescent-state and grace-period-nonstart use of rsp
Now that there is only one rcu_state structure, there is less point in
maintaining a pointer to it. This commit therefore replaces rsp with
&rcu_state in rcu_report_qs_rnp(), force_quiescent_state(), and
rcu_check_gp_start_stall().
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
kernel/rcu/tree.c | 32 +++++++++++++++-----------------
1 file changed, 15 insertions(+), 17 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index e6f0d8b6bde3..962b75c9722a 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2197,7 +2197,6 @@ static void rcu_report_qs_rnp(unsigned long mask, struct rcu_node *rnp,
{
unsigned long oldmask = 0;
struct rcu_node *rnp_c;
- struct rcu_state __maybe_unused *rsp = &rcu_state;
raw_lockdep_assert_held_rcu_node(rnp);
@@ -2216,7 +2215,7 @@ static void rcu_report_qs_rnp(unsigned long mask, struct rcu_node *rnp,
WARN_ON_ONCE(!rcu_is_leaf_node(rnp) &&
rcu_preempt_blocked_readers_cgp(rnp));
rnp->qsmask &= ~mask;
- trace_rcu_quiescent_state_report(rsp->name, rnp->gp_seq,
+ trace_rcu_quiescent_state_report(rcu_state.name, rnp->gp_seq,
mask, rnp->qsmask, rnp->level,
rnp->grplo, rnp->grphi,
!!rnp->gp_tasks);
@@ -2623,12 +2622,11 @@ static void force_quiescent_state(void)
bool ret;
struct rcu_node *rnp;
struct rcu_node *rnp_old = NULL;
- struct rcu_state *rsp = &rcu_state;
/* Funnel through hierarchy to reduce memory contention. */
rnp = __this_cpu_read(rcu_data.mynode);
for (; rnp != NULL; rnp = rnp->parent) {
- ret = (READ_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) ||
+ ret = (READ_ONCE(rcu_state.gp_flags) & RCU_GP_FLAG_FQS) ||
!raw_spin_trylock(&rnp->fqslock);
if (rnp_old != NULL)
raw_spin_unlock(&rnp_old->fqslock);
@@ -2641,11 +2639,12 @@ static void force_quiescent_state(void)
/* Reached the root of the rcu_node tree, acquire lock. */
raw_spin_lock_irqsave_rcu_node(rnp_old, flags);
raw_spin_unlock(&rnp_old->fqslock);
- if (READ_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) {
+ if (READ_ONCE(rcu_state.gp_flags) & RCU_GP_FLAG_FQS) {
raw_spin_unlock_irqrestore_rcu_node(rnp_old, flags);
return; /* Someone beat us to it. */
}
- WRITE_ONCE(rsp->gp_flags, READ_ONCE(rsp->gp_flags) | RCU_GP_FLAG_FQS);
+ WRITE_ONCE(rcu_state.gp_flags,
+ READ_ONCE(rcu_state.gp_flags) | RCU_GP_FLAG_FQS);
raw_spin_unlock_irqrestore_rcu_node(rnp_old, flags);
rcu_gp_kthread_wake();
}
@@ -2661,15 +2660,14 @@ rcu_check_gp_start_stall(struct rcu_node *rnp, struct rcu_data *rdp)
unsigned long flags;
unsigned long j;
struct rcu_node *rnp_root = rcu_get_root();
- struct rcu_state *rsp = &rcu_state;
static atomic_t warned = ATOMIC_INIT(0);
if (!IS_ENABLED(CONFIG_PROVE_RCU) || rcu_gp_in_progress() ||
ULONG_CMP_GE(rnp_root->gp_seq, rnp_root->gp_seq_needed))
return;
j = jiffies; /* Expensive access, and in common case don't get here. */
- if (time_before(j, READ_ONCE(rsp->gp_req_activity) + gpssdelay) ||
- time_before(j, READ_ONCE(rsp->gp_activity) + gpssdelay) ||
+ if (time_before(j, READ_ONCE(rcu_state.gp_req_activity) + gpssdelay) ||
+ time_before(j, READ_ONCE(rcu_state.gp_activity) + gpssdelay) ||
atomic_read(&warned))
return;
@@ -2677,8 +2675,8 @@ rcu_check_gp_start_stall(struct rcu_node *rnp, struct rcu_data *rdp)
j = jiffies;
if (rcu_gp_in_progress() ||
ULONG_CMP_GE(rnp_root->gp_seq, rnp_root->gp_seq_needed) ||
- time_before(j, READ_ONCE(rsp->gp_req_activity) + gpssdelay) ||
- time_before(j, READ_ONCE(rsp->gp_activity) + gpssdelay) ||
+ time_before(j, READ_ONCE(rcu_state.gp_req_activity) + gpssdelay) ||
+ time_before(j, READ_ONCE(rcu_state.gp_activity) + gpssdelay) ||
atomic_read(&warned)) {
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
return;
@@ -2690,19 +2688,19 @@ rcu_check_gp_start_stall(struct rcu_node *rnp, struct rcu_data *rdp)
j = jiffies;
if (rcu_gp_in_progress() ||
ULONG_CMP_GE(rnp_root->gp_seq, rnp_root->gp_seq_needed) ||
- time_before(j, rsp->gp_req_activity + gpssdelay) ||
- time_before(j, rsp->gp_activity + gpssdelay) ||
+ time_before(j, rcu_state.gp_req_activity + gpssdelay) ||
+ time_before(j, rcu_state.gp_activity + gpssdelay) ||
atomic_xchg(&warned, 1)) {
raw_spin_unlock_rcu_node(rnp_root); /* irqs remain disabled. */
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
return;
}
pr_alert("%s: g%ld->%ld gar:%lu ga:%lu f%#x gs:%d %s->state:%#lx\n",
- __func__, (long)READ_ONCE(rsp->gp_seq),
+ __func__, (long)READ_ONCE(rcu_state.gp_seq),
(long)READ_ONCE(rnp_root->gp_seq_needed),
- j - rsp->gp_req_activity, j - rsp->gp_activity,
- rsp->gp_flags, rsp->gp_state, rsp->name,
- rsp->gp_kthread ? rsp->gp_kthread->state : 0x1ffffL);
+ j - rcu_state.gp_req_activity, j - rcu_state.gp_activity,
+ rcu_state.gp_flags, rcu_state.gp_state, rcu_state.name,
+ rcu_state.gp_kthread ? rcu_state.gp_kthread->state : 0x1ffffL);
WARN_ON(1);
if (rnp_root != rnp)
raw_spin_unlock_rcu_node(rnp_root);
--
2.17.1
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