rcu: Switch dyntick nesting counters to rcu_data structure

This commit removes ->dynticks_nesting and ->dynticks_nmi_nesting from
the rcu_dynticks structure and updates the code to access them from the
rcu_data structure.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 7ec0ba8..bfa264a 100644 (file)
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -73,7 +73,10 @@
 
 /* Data structures. */
 
-static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_data, rcu_data);
+static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_data, rcu_data) = {
+       .dynticks_nesting = 1,
+       .dynticks_nmi_nesting = DYNTICK_IRQ_NONIDLE,
+};
 struct rcu_state rcu_state = {
        .level = { &rcu_state.node[0] },
        .gp_state = RCU_GP_IDLE,
@@ -210,8 +213,6 @@ void rcu_softirq_qs(void)
 #endif
 
 static DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = {
-       .dynticks_nesting = 1,
-       .dynticks_nmi_nesting = DYNTICK_IRQ_NONIDLE,
        .dynticks = ATOMIC_INIT(RCU_DYNTICK_CTRL_CTR),
 };
 
@@ -378,8 +379,8 @@ static void __maybe_unused rcu_momentary_dyntick_idle(void)
  */
 static int rcu_is_cpu_rrupt_from_idle(void)
 {
-       return __this_cpu_read(rcu_dynticks.dynticks_nesting) <= 0 &&
-              __this_cpu_read(rcu_dynticks.dynticks_nmi_nesting) <= 1;
+       return __this_cpu_read(rcu_data.dynticks_nesting) <= 0 &&
+              __this_cpu_read(rcu_data.dynticks_nmi_nesting) <= 1;
 }
 
 #define DEFAULT_RCU_BLIMIT 10     /* Maximum callbacks per rcu_do_batch. */
@@ -571,27 +572,27 @@ static struct rcu_node *rcu_get_root(void)
  */
 static void rcu_eqs_enter(bool user)
 {
-       struct rcu_data *rdp;
+       struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
        struct rcu_dynticks *rdtp;
 
        rdtp = this_cpu_ptr(&rcu_dynticks);
-       WARN_ON_ONCE(rdtp->dynticks_nmi_nesting != DYNTICK_IRQ_NONIDLE);
-       WRITE_ONCE(rdtp->dynticks_nmi_nesting, 0);
+       WARN_ON_ONCE(rdp->dynticks_nmi_nesting != DYNTICK_IRQ_NONIDLE);
+       WRITE_ONCE(rdp->dynticks_nmi_nesting, 0);
        WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
-                    rdtp->dynticks_nesting == 0);
-       if (rdtp->dynticks_nesting != 1) {
-               rdtp->dynticks_nesting--;
+                    rdp->dynticks_nesting == 0);
+       if (rdp->dynticks_nesting != 1) {
+               rdp->dynticks_nesting--;
                return;
        }
 
        lockdep_assert_irqs_disabled();
-       trace_rcu_dyntick(TPS("Start"), rdtp->dynticks_nesting, 0, rdtp->dynticks);
+       trace_rcu_dyntick(TPS("Start"), rdp->dynticks_nesting, 0, rdtp->dynticks);
        WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
        rdp = this_cpu_ptr(&rcu_data);
        do_nocb_deferred_wakeup(rdp);
        rcu_prepare_for_idle();
        rcu_preempt_deferred_qs(current);
-       WRITE_ONCE(rdtp->dynticks_nesting, 0); /* Avoid irq-access tearing. */
+       WRITE_ONCE(rdp->dynticks_nesting, 0); /* Avoid irq-access tearing. */
        rcu_dynticks_eqs_enter();
        rcu_dynticks_task_enter();
 }
@@ -634,7 +635,7 @@ void rcu_user_enter(void)
 
 /*
  * If we are returning from the outermost NMI handler that interrupted an
- * RCU-idle period, update rdtp->dynticks and rdtp->dynticks_nmi_nesting
+ * RCU-idle period, update rdtp->dynticks and rdp->dynticks_nmi_nesting
  * to let the RCU grace-period handling know that the CPU is back to
  * being RCU-idle.
  *
@@ -643,30 +644,31 @@ void rcu_user_enter(void)
  */
 static __always_inline void rcu_nmi_exit_common(bool irq)
 {
-       struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
+       struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
+       struct rcu_dynticks __maybe_unused *rdtp = this_cpu_ptr(&rcu_dynticks);
 
        /*
         * Check for ->dynticks_nmi_nesting underflow and bad ->dynticks.
         * (We are exiting an NMI handler, so RCU better be paying attention
         * to us!)
         */
-       WARN_ON_ONCE(rdtp->dynticks_nmi_nesting <= 0);
+       WARN_ON_ONCE(rdp->dynticks_nmi_nesting <= 0);
        WARN_ON_ONCE(rcu_dynticks_curr_cpu_in_eqs());
 
        /*
         * If the nesting level is not 1, the CPU wasn't RCU-idle, so
         * leave it in non-RCU-idle state.
         */
-       if (rdtp->dynticks_nmi_nesting != 1) {
-               trace_rcu_dyntick(TPS("--="), rdtp->dynticks_nmi_nesting, rdtp->dynticks_nmi_nesting - 2, rdtp->dynticks);
-               WRITE_ONCE(rdtp->dynticks_nmi_nesting, /* No store tearing. */
-                          rdtp->dynticks_nmi_nesting - 2);
+       if (rdp->dynticks_nmi_nesting != 1) {
+               trace_rcu_dyntick(TPS("--="), rdp->dynticks_nmi_nesting, rdp->dynticks_nmi_nesting - 2, rdtp->dynticks);
+               WRITE_ONCE(rdp->dynticks_nmi_nesting, /* No store tearing. */
+                          rdp->dynticks_nmi_nesting - 2);
                return;
        }
 
        /* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */
-       trace_rcu_dyntick(TPS("Startirq"), rdtp->dynticks_nmi_nesting, 0, rdtp->dynticks);
-       WRITE_ONCE(rdtp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */
+       trace_rcu_dyntick(TPS("Startirq"), rdp->dynticks_nmi_nesting, 0, rdtp->dynticks);
+       WRITE_ONCE(rdp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */
 
        if (irq)
                rcu_prepare_for_idle();
@@ -739,25 +741,27 @@ void rcu_irq_exit_irqson(void)
  */
 static void rcu_eqs_exit(bool user)
 {
+       struct rcu_data *rdp;
        struct rcu_dynticks *rdtp;
        long oldval;
 
        lockdep_assert_irqs_disabled();
        rdtp = this_cpu_ptr(&rcu_dynticks);
-       oldval = rdtp->dynticks_nesting;
+       rdp = this_cpu_ptr(&rcu_data);
+       oldval = rdp->dynticks_nesting;
        WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && oldval < 0);
        if (oldval) {
-               rdtp->dynticks_nesting++;
+               rdp->dynticks_nesting++;
                return;
        }
        rcu_dynticks_task_exit();
        rcu_dynticks_eqs_exit();
        rcu_cleanup_after_idle();
-       trace_rcu_dyntick(TPS("End"), rdtp->dynticks_nesting, 1, rdtp->dynticks);
+       trace_rcu_dyntick(TPS("End"), rdp->dynticks_nesting, 1, rdtp->dynticks);
        WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
-       WRITE_ONCE(rdtp->dynticks_nesting, 1);
-       WARN_ON_ONCE(rdtp->dynticks_nmi_nesting);
-       WRITE_ONCE(rdtp->dynticks_nmi_nesting, DYNTICK_IRQ_NONIDLE);
+       WRITE_ONCE(rdp->dynticks_nesting, 1);
+       WARN_ON_ONCE(rdp->dynticks_nmi_nesting);
+       WRITE_ONCE(rdp->dynticks_nmi_nesting, DYNTICK_IRQ_NONIDLE);
 }
 
 /**
@@ -799,7 +803,7 @@ void rcu_user_exit(void)
  * @irq: Is this call from rcu_irq_enter?
  *
  * If the CPU was idle from RCU's viewpoint, update rdtp->dynticks and
- * rdtp->dynticks_nmi_nesting to let the RCU grace-period handling know
+ * rdp->dynticks_nmi_nesting to let the RCU grace-period handling know
  * that the CPU is active.  This implementation permits nested NMIs, as
  * long as the nesting level does not overflow an int.  (You will probably
  * run out of stack space first.)
@@ -809,11 +813,12 @@ void rcu_user_exit(void)
  */
 static __always_inline void rcu_nmi_enter_common(bool irq)
 {
-       struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
+       struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
+       struct rcu_dynticks __maybe_unused *rdtp = this_cpu_ptr(&rcu_dynticks);
        long incby = 2;
 
        /* Complain about underflow. */
-       WARN_ON_ONCE(rdtp->dynticks_nmi_nesting < 0);
+       WARN_ON_ONCE(rdp->dynticks_nmi_nesting < 0);
 
        /*
         * If idle from RCU viewpoint, atomically increment ->dynticks
@@ -836,10 +841,10 @@ static __always_inline void rcu_nmi_enter_common(bool irq)
                incby = 1;
        }
        trace_rcu_dyntick(incby == 1 ? TPS("Endirq") : TPS("++="),
-                         rdtp->dynticks_nmi_nesting,
-                         rdtp->dynticks_nmi_nesting + incby, rdtp->dynticks);
-       WRITE_ONCE(rdtp->dynticks_nmi_nesting, /* Prevent store tearing. */
-                  rdtp->dynticks_nmi_nesting + incby);
+                         rdp->dynticks_nmi_nesting,
+                         rdp->dynticks_nmi_nesting + incby, rdtp->dynticks);
+       WRITE_ONCE(rdp->dynticks_nmi_nesting, /* Prevent store tearing. */
+                  rdp->dynticks_nmi_nesting + incby);
        barrier();
 }
 
@@ -3194,7 +3199,7 @@ rcu_boot_init_percpu_data(int cpu)
        /* Set up local state, ensuring consistent view of global state. */
        rdp->grpmask = leaf_node_cpu_bit(rdp->mynode, cpu);
        rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
-       WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != 1);
+       WARN_ON_ONCE(rdp->dynticks_nesting != 1);
        WARN_ON_ONCE(rcu_dynticks_in_eqs(rcu_dynticks_snap(rdp->dynticks)));
        rdp->rcu_ofl_gp_seq = rcu_state.gp_seq;
        rdp->rcu_ofl_gp_flags = RCU_GP_CLEANED;
@@ -3227,7 +3232,7 @@ int rcutree_prepare_cpu(unsigned int cpu)
        if (rcu_segcblist_empty(&rdp->cblist) && /* No early-boot CBs? */
            !init_nocb_callback_list(rdp))
                rcu_segcblist_init(&rdp->cblist);  /* Re-enable callbacks. */
-       rdp->dynticks->dynticks_nesting = 1;    /* CPU not up, no tearing. */
+       rdp->dynticks_nesting = 1;      /* CPU not up, no tearing. */
        rcu_dynticks_eqs_online();
        raw_spin_unlock_rcu_node(rnp);          /* irqs remain disabled. */
 

diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 4c31066..2e5eec4 100644 (file)
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -38,8 +38,6 @@
  * Dynticks per-CPU state.
  */
 struct rcu_dynticks {
-       long dynticks_nesting;      /* Track process nesting level. */
-       long dynticks_nmi_nesting;  /* Track irq/NMI nesting level. */
        atomic_t dynticks;          /* Even value for idle, else odd. */
 };
 

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 1617609..7087ee3 100644 (file)
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1831,7 +1831,7 @@ static void print_cpu_stall_info(int cpu)
                                "!."[!delta],
               ticks_value, ticks_title,
               rcu_dynticks_snap(rdtp) & 0xfff,
-              rdtp->dynticks_nesting, rdtp->dynticks_nmi_nesting,
+              rdp->dynticks_nesting, rdp->dynticks_nmi_nesting,
               rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu),
               READ_ONCE(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart,
               fast_no_hz);