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Message-Id: <20180829223854.4055-32-paulmck@linux.vnet.ibm.com>
Date: Wed, 29 Aug 2018 15:38:34 -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 32/52] rcu: Remove rsp parameter from rcu_boot_init_percpu_data() and friends
There now is only one rcu_state structure in a given build of
the Linux kernel, so there is no need to pass it as a parameter
to RCU's functions. This commit therefore removes the rsp
parameter from rcu_boot_init_percpu_data(), rcu_init_percpu_data(),
rcu_cleanup_dying_idle_cpu(), and rcu_migrate_callbacks(). While in
the neighborhood, line the last three into rcutree_prepare_cpu(),
rcu_report_dead() and rcutree_migrate_callbacks(), respectively.
This also gets rid of the for_each_rcu_flavor() calls that were in
those tree functions.
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
kernel/rcu/tree.c | 102 ++++++++++++++++------------------------------
1 file changed, 35 insertions(+), 67 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 8028936dc95d..3591633efc33 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3351,7 +3351,7 @@ static void rcu_init_new_rnp(struct rcu_node *rnp_leaf)
* Do boot-time initialization of a CPU's per-CPU RCU data.
*/
static void __init
-rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
+rcu_boot_init_percpu_data(int cpu)
{
struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
@@ -3360,23 +3360,25 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != 1);
WARN_ON_ONCE(rcu_dynticks_in_eqs(rcu_dynticks_snap(rdp->dynticks)));
- rdp->rcu_ofl_gp_seq = rsp->gp_seq;
+ rdp->rcu_ofl_gp_seq = rcu_state.gp_seq;
rdp->rcu_ofl_gp_flags = RCU_GP_CLEANED;
- rdp->rcu_onl_gp_seq = rsp->gp_seq;
+ rdp->rcu_onl_gp_seq = rcu_state.gp_seq;
rdp->rcu_onl_gp_flags = RCU_GP_CLEANED;
rdp->cpu = cpu;
- rdp->rsp = rsp;
+ rdp->rsp = &rcu_state;
rcu_boot_init_nocb_percpu_data(rdp);
}
/*
- * Initialize a CPU's per-CPU RCU data. Note that only one online or
+ * Invoked early in the CPU-online process, when pretty much all services
+ * are available. The incoming CPU is not present.
+ *
+ * Initializes a CPU's per-CPU RCU data. Note that only one online or
* offline event can be happening at a given time. Note also that we can
* accept some slop in the rsp->gp_seq access due to the fact that this
* CPU cannot possibly have any RCU callbacks in flight yet.
*/
-static void
-rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
+int rcutree_prepare_cpu(unsigned int cpu)
{
unsigned long flags;
struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
@@ -3385,7 +3387,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
/* Set up local state, ensuring consistent view of global state. */
raw_spin_lock_irqsave_rcu_node(rnp, flags);
rdp->qlen_last_fqs_check = 0;
- rdp->n_force_qs_snap = rsp->n_force_qs;
+ rdp->n_force_qs_snap = rcu_state.n_force_qs;
rdp->blimit = blimit;
if (rcu_segcblist_empty(&rdp->cblist) && /* No early-boot CBs? */
!init_nocb_callback_list(rdp))
@@ -3409,21 +3411,8 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
rdp->core_needs_qs = false;
rdp->rcu_iw_pending = false;
rdp->rcu_iw_gp_seq = rnp->gp_seq - 1;
- trace_rcu_grace_period(rsp->name, rdp->gp_seq, TPS("cpuonl"));
+ trace_rcu_grace_period(rcu_state.name, rdp->gp_seq, TPS("cpuonl"));
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
-}
-
-/*
- * Invoked early in the CPU-online process, when pretty much all
- * services are available. The incoming CPU is not present.
- */
-int rcutree_prepare_cpu(unsigned int cpu)
-{
- struct rcu_state *rsp;
-
- for_each_rcu_flavor(rsp)
- rcu_init_percpu_data(cpu, rsp);
-
rcu_prepare_kthreads(cpu);
rcu_spawn_all_nocb_kthreads(cpu);
@@ -3547,23 +3536,32 @@ void rcu_cpu_starting(unsigned int cpu)
#ifdef CONFIG_HOTPLUG_CPU
/*
- * The CPU is exiting the idle loop into the arch_cpu_idle_dead()
- * function. We now remove it from the rcu_node tree's ->qsmaskinitnext
- * bit masks.
+ * The outgoing function has no further need of RCU, so remove it from
+ * the rcu_node tree's ->qsmaskinitnext bit masks.
+ *
+ * Note that this function is special in that it is invoked directly
+ * from the outgoing CPU rather than from the cpuhp_step mechanism.
+ * This is because this function must be invoked at a precise location.
*/
-static void rcu_cleanup_dying_idle_cpu(int cpu, struct rcu_state *rsp)
+void rcu_report_dead(unsigned int cpu)
{
unsigned long flags;
unsigned long mask;
struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
struct rcu_node *rnp = rdp->mynode; /* Outgoing CPU's rdp & rnp. */
+ /* QS for any half-done expedited RCU-sched GP. */
+ preempt_disable();
+ rcu_report_exp_rdp(&rcu_state, this_cpu_ptr(&rcu_data));
+ preempt_enable();
+ rcu_preempt_deferred_qs(current);
+
/* Remove outgoing CPU from mask in the leaf rcu_node structure. */
mask = rdp->grpmask;
- spin_lock(&rsp->ofl_lock);
+ spin_lock(&rcu_state.ofl_lock);
raw_spin_lock_irqsave_rcu_node(rnp, flags); /* Enforce GP memory-order guarantee. */
- rdp->rcu_ofl_gp_seq = READ_ONCE(rsp->gp_seq);
- rdp->rcu_ofl_gp_flags = READ_ONCE(rsp->gp_flags);
+ rdp->rcu_ofl_gp_seq = READ_ONCE(rcu_state.gp_seq);
+ rdp->rcu_ofl_gp_flags = READ_ONCE(rcu_state.gp_flags);
if (rnp->qsmask & mask) { /* RCU waiting on outgoing CPU? */
/* Report quiescent state -before- changing ->qsmaskinitnext! */
rcu_report_qs_rnp(mask, rnp, rnp->gp_seq, flags);
@@ -3571,34 +3569,17 @@ static void rcu_cleanup_dying_idle_cpu(int cpu, struct rcu_state *rsp)
}
rnp->qsmaskinitnext &= ~mask;
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
- spin_unlock(&rsp->ofl_lock);
-}
-
-/*
- * The outgoing function has no further need of RCU, so remove it from
- * the list of CPUs that RCU must track.
- *
- * Note that this function is special in that it is invoked directly
- * from the outgoing CPU rather than from the cpuhp_step mechanism.
- * This is because this function must be invoked at a precise location.
- */
-void rcu_report_dead(unsigned int cpu)
-{
- struct rcu_state *rsp;
-
- /* QS for any half-done expedited RCU-sched GP. */
- preempt_disable();
- rcu_report_exp_rdp(&rcu_state, this_cpu_ptr(&rcu_data));
- preempt_enable();
- rcu_preempt_deferred_qs(current);
- for_each_rcu_flavor(rsp)
- rcu_cleanup_dying_idle_cpu(cpu, rsp);
+ spin_unlock(&rcu_state.ofl_lock);
per_cpu(rcu_cpu_started, cpu) = 0;
}
-/* Migrate the dead CPU's callbacks to the current CPU. */
-static void rcu_migrate_callbacks(int cpu, struct rcu_state *rsp)
+/*
+ * The outgoing CPU has just passed through the dying-idle state, and we
+ * are being invoked from the CPU that was IPIed to continue the offline
+ * operation. Migrate the outgoing CPU's callbacks to the current CPU.
+ */
+void rcutree_migrate_callbacks(int cpu)
{
unsigned long flags;
struct rcu_data *my_rdp;
@@ -3631,19 +3612,6 @@ static void rcu_migrate_callbacks(int cpu, struct rcu_state *rsp)
cpu, rcu_segcblist_n_cbs(&rdp->cblist),
rcu_segcblist_first_cb(&rdp->cblist));
}
-
-/*
- * The outgoing CPU has just passed through the dying-idle state,
- * and we are being invoked from the CPU that was IPIed to continue the
- * offline operation. We need to migrate the outgoing CPU's callbacks.
- */
-void rcutree_migrate_callbacks(int cpu)
-{
- struct rcu_state *rsp;
-
- for_each_rcu_flavor(rsp)
- rcu_migrate_callbacks(cpu, rsp);
-}
#endif
/*
@@ -3813,7 +3781,7 @@ static void __init rcu_init_one(struct rcu_state *rsp)
while (i > rnp->grphi)
rnp++;
per_cpu_ptr(&rcu_data, i)->mynode = rnp;
- rcu_boot_init_percpu_data(i, rsp);
+ rcu_boot_init_percpu_data(i);
}
list_add(&rsp->flavors, &rcu_struct_flavors);
}
--
2.17.1
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