rcu/context_tracking: Move dynticks counter to context tracking

In order to prepare for merging RCU dynticks counter into the context
tracking state, move the rcu_data's dynticks field to the context
tracking structure. It will later be mixed within the context tracking
state itself.

[ paulmck: Move enum ctx_state into global scope. ]

Acked-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Tested-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>

diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h
index 9c16a8b2c1947a313531b4f44946878b6408fcf8..5a8da2787287e9a46c1fc54b72a4f672e0afd8d0 100644 (file)
--- a/include/linux/context_tracking_state.h
+++ b/include/linux/context_tracking_state.h
@@ -6,7 +6,15 @@
 #include <linux/static_key.h>
 #include <linux/context_tracking_irq.h>
 
+enum ctx_state {
+       CONTEXT_DISABLED = -1,  /* returned by ct_state() if unknown */
+       CONTEXT_KERNEL = 0,
+       CONTEXT_USER,
+       CONTEXT_GUEST,
+};
+
 struct context_tracking {
+#ifdef CONFIG_CONTEXT_TRACKING_USER
        /*
         * When active is false, probes are unset in order
         * to minimize overhead: TIF flags are cleared
@@ -15,17 +23,40 @@ struct context_tracking {
         */
        bool active;
        int recursion;
-       enum ctx_state {
-               CONTEXT_DISABLED = -1,  /* returned by ct_state() if unknown */
-               CONTEXT_KERNEL = 0,
-               CONTEXT_USER,
-               CONTEXT_GUEST,
-       } state;
+       enum ctx_state state;
+#endif
+#ifdef CONFIG_CONTEXT_TRACKING_IDLE
+       atomic_t dynticks;              /* Even value for idle, else odd. */
+#endif
 };
 
+#ifdef CONFIG_CONTEXT_TRACKING
+DECLARE_PER_CPU(struct context_tracking, context_tracking);
+#endif
+
+#ifdef CONFIG_CONTEXT_TRACKING_IDLE
+static __always_inline int ct_dynticks(void)
+{
+       return atomic_read(this_cpu_ptr(&context_tracking.dynticks));
+}
+
+static __always_inline int ct_dynticks_cpu(int cpu)
+{
+       struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
+
+       return atomic_read(&ct->dynticks);
+}
+
+static __always_inline int ct_dynticks_cpu_acquire(int cpu)
+{
+       struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
+
+       return atomic_read_acquire(&ct->dynticks);
+}
+#endif /* #ifdef CONFIG_CONTEXT_TRACKING_IDLE */
+
 #ifdef CONFIG_CONTEXT_TRACKING_USER
 extern struct static_key_false context_tracking_key;
-DECLARE_PER_CPU(struct context_tracking, context_tracking);
 
 static __always_inline bool context_tracking_enabled(void)
 {

diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index c0d86dac98f1cebb17f5c3eb037ca71006932bd5..01abbcec52f7aec797d0a1f9e2f8d56abcf6ccd9 100644 (file)
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -23,6 +23,13 @@
 #include <linux/kprobes.h>
 
 
+DEFINE_PER_CPU(struct context_tracking, context_tracking) = {
+#ifdef CONFIG_CONTEXT_TRACKING_IDLE
+       .dynticks = ATOMIC_INIT(1),
+#endif
+};
+EXPORT_SYMBOL_GPL(context_tracking);
+
 #ifdef CONFIG_CONTEXT_TRACKING_IDLE
 noinstr void ct_idle_enter(void)
 {
@@ -138,9 +145,6 @@ noinstr void ct_nmi_exit(void)
 DEFINE_STATIC_KEY_FALSE(context_tracking_key);
 EXPORT_SYMBOL_GPL(context_tracking_key);
 
-DEFINE_PER_CPU(struct context_tracking, context_tracking);
-EXPORT_SYMBOL_GPL(context_tracking);
-
 static noinstr bool context_tracking_recursion_enter(void)
 {
        int recursion;

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 75b433dba42766643f8abd6e396854db74e00f47..a471edc3d893816e5000cf409401c9fa34e525ab 100644 (file)
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -77,7 +77,6 @@
 static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_data, rcu_data) = {
        .dynticks_nesting = 1,
        .dynticks_nmi_nesting = DYNTICK_IRQ_NONIDLE,
-       .dynticks = ATOMIC_INIT(1),
 #ifdef CONFIG_RCU_NOCB_CPU
        .cblist.flags = SEGCBLIST_RCU_CORE,
 #endif
@@ -268,7 +267,7 @@ void rcu_softirq_qs(void)
  */
 static noinline noinstr unsigned long rcu_dynticks_inc(int incby)
 {
-       return arch_atomic_add_return(incby, this_cpu_ptr(&rcu_data.dynticks));
+       return arch_atomic_add_return(incby, this_cpu_ptr(&context_tracking.dynticks));
 }
 
 /*
@@ -324,9 +323,7 @@ static noinstr void rcu_dynticks_eqs_exit(void)
  */
 static void rcu_dynticks_eqs_online(void)
 {
-       struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
-
-       if (atomic_read(&rdp->dynticks) & 0x1)
+       if (ct_dynticks() & 0x1)
                return;
        rcu_dynticks_inc(1);
 }
@@ -338,17 +335,17 @@ static void rcu_dynticks_eqs_online(void)
  */
 static __always_inline bool rcu_dynticks_curr_cpu_in_eqs(void)
 {
-       return !(arch_atomic_read(this_cpu_ptr(&rcu_data.dynticks)) & 0x1);
+       return !(arch_atomic_read(this_cpu_ptr(&context_tracking.dynticks)) & 0x1);
 }
 
 /*
  * Snapshot the ->dynticks counter with full ordering so as to allow
  * stable comparison of this counter with past and future snapshots.
  */
-static int rcu_dynticks_snap(struct rcu_data *rdp)
+static int rcu_dynticks_snap(int cpu)
 {
        smp_mb();  // Fundamental RCU ordering guarantee.
-       return atomic_read_acquire(&rdp->dynticks);
+       return ct_dynticks_cpu_acquire(cpu);
 }
 
 /*
@@ -363,9 +360,7 @@ static bool rcu_dynticks_in_eqs(int snap)
 /* Return true if the specified CPU is currently idle from an RCU viewpoint.  */
 bool rcu_is_idle_cpu(int cpu)
 {
-       struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
-
-       return rcu_dynticks_in_eqs(rcu_dynticks_snap(rdp));
+       return rcu_dynticks_in_eqs(rcu_dynticks_snap(cpu));
 }
 
 /*
@@ -375,7 +370,7 @@ bool rcu_is_idle_cpu(int cpu)
  */
 static bool rcu_dynticks_in_eqs_since(struct rcu_data *rdp, int snap)
 {
-       return snap != rcu_dynticks_snap(rdp);
+       return snap != rcu_dynticks_snap(rdp->cpu);
 }
 
 /*
@@ -384,11 +379,10 @@ static bool rcu_dynticks_in_eqs_since(struct rcu_data *rdp, int snap)
  */
 bool rcu_dynticks_zero_in_eqs(int cpu, int *vp)
 {
-       struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
        int snap;
 
        // If not quiescent, force back to earlier extended quiescent state.
-       snap = atomic_read(&rdp->dynticks) & ~0x1;
+       snap = ct_dynticks_cpu(cpu) & ~0x1;
 
        smp_rmb(); // Order ->dynticks and *vp reads.
        if (READ_ONCE(*vp))
@@ -396,7 +390,7 @@ bool rcu_dynticks_zero_in_eqs(int cpu, int *vp)
        smp_rmb(); // Order *vp read and ->dynticks re-read.
 
        // If still in the same extended quiescent state, we are good!
-       return snap == atomic_read(&rdp->dynticks);
+       return snap == ct_dynticks_cpu(cpu);
 }
 
 /*
@@ -620,6 +614,7 @@ EXPORT_SYMBOL_GPL(rcutorture_get_gp_data);
 static noinstr void rcu_eqs_enter(bool user)
 {
        struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
+       struct context_tracking *ct = this_cpu_ptr(&context_tracking);
 
        WARN_ON_ONCE(rdp->dynticks_nmi_nesting != DYNTICK_IRQ_NONIDLE);
        WRITE_ONCE(rdp->dynticks_nmi_nesting, 0);
@@ -633,12 +628,12 @@ static noinstr void rcu_eqs_enter(bool user)
 
        instrumentation_begin();
        lockdep_assert_irqs_disabled();
-       trace_rcu_dyntick(TPS("Start"), rdp->dynticks_nesting, 0, atomic_read(&rdp->dynticks));
+       trace_rcu_dyntick(TPS("Start"), rdp->dynticks_nesting, 0, ct_dynticks());
        WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
        rcu_preempt_deferred_qs(current);
 
        // instrumentation for the noinstr rcu_dynticks_eqs_enter()
-       instrument_atomic_write(&rdp->dynticks, sizeof(rdp->dynticks));
+       instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
 
        instrumentation_end();
        WRITE_ONCE(rdp->dynticks_nesting, 0); /* Avoid irq-access tearing. */
@@ -740,7 +735,7 @@ noinstr void rcu_user_enter(void)
  * rcu_nmi_exit - inform RCU of exit from NMI context
  *
  * If we are returning from the outermost NMI handler that interrupted an
- * RCU-idle period, update rdp->dynticks and rdp->dynticks_nmi_nesting
+ * RCU-idle period, update ct->dynticks and rdp->dynticks_nmi_nesting
  * to let the RCU grace-period handling know that the CPU is back to
  * being RCU-idle.
  *
@@ -749,6 +744,7 @@ noinstr void rcu_user_enter(void)
  */
 noinstr void rcu_nmi_exit(void)
 {
+       struct context_tracking *ct = this_cpu_ptr(&context_tracking);
        struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
 
        instrumentation_begin();
@@ -766,7 +762,7 @@ noinstr void rcu_nmi_exit(void)
         */
        if (rdp->dynticks_nmi_nesting != 1) {
                trace_rcu_dyntick(TPS("--="), rdp->dynticks_nmi_nesting, rdp->dynticks_nmi_nesting - 2,
-                                 atomic_read(&rdp->dynticks));
+                                 ct_dynticks());
                WRITE_ONCE(rdp->dynticks_nmi_nesting, /* No store tearing. */
                           rdp->dynticks_nmi_nesting - 2);
                instrumentation_end();
@@ -774,11 +770,11 @@ noinstr void rcu_nmi_exit(void)
        }
 
        /* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */
-       trace_rcu_dyntick(TPS("Startirq"), rdp->dynticks_nmi_nesting, 0, atomic_read(&rdp->dynticks));
+       trace_rcu_dyntick(TPS("Startirq"), rdp->dynticks_nmi_nesting, 0, ct_dynticks());
        WRITE_ONCE(rdp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */
 
        // instrumentation for the noinstr rcu_dynticks_eqs_enter()
-       instrument_atomic_write(&rdp->dynticks, sizeof(rdp->dynticks));
+       instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
        instrumentation_end();
 
        // RCU is watching here ...
@@ -817,6 +813,7 @@ void rcu_irq_exit_check_preempt(void)
  */
 static void noinstr rcu_eqs_exit(bool user)
 {
+       struct context_tracking *ct = this_cpu_ptr(&context_tracking);
        struct rcu_data *rdp;
        long oldval;
 
@@ -836,9 +833,9 @@ static void noinstr rcu_eqs_exit(bool user)
        instrumentation_begin();
 
        // instrumentation for the noinstr rcu_dynticks_eqs_exit()
-       instrument_atomic_write(&rdp->dynticks, sizeof(rdp->dynticks));
+       instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
 
-       trace_rcu_dyntick(TPS("End"), rdp->dynticks_nesting, 1, atomic_read(&rdp->dynticks));
+       trace_rcu_dyntick(TPS("End"), rdp->dynticks_nesting, 1, ct_dynticks());
        WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
        WRITE_ONCE(rdp->dynticks_nesting, 1);
        WARN_ON_ONCE(rdp->dynticks_nmi_nesting);
@@ -944,7 +941,7 @@ void __rcu_irq_enter_check_tick(void)
 /**
  * rcu_nmi_enter - inform RCU of entry to NMI context
  *
- * If the CPU was idle from RCU's viewpoint, update rdp->dynticks and
+ * If the CPU was idle from RCU's viewpoint, update ct->dynticks and
  * 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
@@ -957,6 +954,7 @@ noinstr void rcu_nmi_enter(void)
 {
        long incby = 2;
        struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
+       struct context_tracking *ct = this_cpu_ptr(&context_tracking);
 
        /* Complain about underflow. */
        WARN_ON_ONCE(rdp->dynticks_nmi_nesting < 0);
@@ -980,9 +978,9 @@ noinstr void rcu_nmi_enter(void)
 
                instrumentation_begin();
                // instrumentation for the noinstr rcu_dynticks_curr_cpu_in_eqs()
-               instrument_atomic_read(&rdp->dynticks, sizeof(rdp->dynticks));
+               instrument_atomic_read(&ct->dynticks, sizeof(ct->dynticks));
                // instrumentation for the noinstr rcu_dynticks_eqs_exit()
-               instrument_atomic_write(&rdp->dynticks, sizeof(rdp->dynticks));
+               instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
 
                incby = 1;
        } else if (!in_nmi()) {
@@ -994,7 +992,7 @@ noinstr void rcu_nmi_enter(void)
 
        trace_rcu_dyntick(incby == 1 ? TPS("Endirq") : TPS("++="),
                          rdp->dynticks_nmi_nesting,
-                         rdp->dynticks_nmi_nesting + incby, atomic_read(&rdp->dynticks));
+                         rdp->dynticks_nmi_nesting + incby, ct_dynticks());
        instrumentation_end();
        WRITE_ONCE(rdp->dynticks_nmi_nesting, /* Prevent store tearing. */
                   rdp->dynticks_nmi_nesting + incby);
@@ -1138,7 +1136,7 @@ static void rcu_gpnum_ovf(struct rcu_node *rnp, struct rcu_data *rdp)
  */
 static int dyntick_save_progress_counter(struct rcu_data *rdp)
 {
-       rdp->dynticks_snap = rcu_dynticks_snap(rdp);
+       rdp->dynticks_snap = rcu_dynticks_snap(rdp->cpu);
        if (rcu_dynticks_in_eqs(rdp->dynticks_snap)) {
                trace_rcu_fqs(rcu_state.name, rdp->gp_seq, rdp->cpu, TPS("dti"));
                rcu_gpnum_ovf(rdp->mynode, rdp);
@@ -4142,7 +4140,7 @@ rcu_boot_init_percpu_data(int cpu)
        rdp->grpmask = leaf_node_cpu_bit(rdp->mynode, cpu);
        INIT_WORK(&rdp->strict_work, strict_work_handler);
        WARN_ON_ONCE(rdp->dynticks_nesting != 1);
-       WARN_ON_ONCE(rcu_dynticks_in_eqs(rcu_dynticks_snap(rdp)));
+       WARN_ON_ONCE(rcu_dynticks_in_eqs(rcu_dynticks_snap(cpu)));
        rdp->barrier_seq_snap = rcu_state.barrier_sequence;
        rdp->rcu_ofl_gp_seq = rcu_state.gp_seq;
        rdp->rcu_ofl_gp_flags = RCU_GP_CLEANED;

diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 2ccf5845957df4201a814de0540b8fbabc6e9412..ebb973f5b1900304a2dad85087d04a461a1d08b1 100644 (file)
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -189,7 +189,6 @@ struct rcu_data {
        int dynticks_snap;              /* Per-GP tracking for 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. */
        bool rcu_need_heavy_qs;         /* GP old, so heavy quiescent state! */
        bool rcu_urgent_qs;             /* GP old need light quiescent state. */
        bool rcu_forced_tick;           /* Forced tick to provide QS. */

diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index 0f70f62039a909067eb7cc9a7884bb09a6e3e612..75c22d1034c1e5a1901c54d995db84d9cb3aa4f6 100644 (file)
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -356,7 +356,7 @@ static void __sync_rcu_exp_select_node_cpus(struct rcu_exp_work *rewp)
                    !(rnp->qsmaskinitnext & mask)) {
                        mask_ofl_test |= mask;
                } else {
-                       snap = rcu_dynticks_snap(rdp);
+                       snap = rcu_dynticks_snap(cpu);
                        if (rcu_dynticks_in_eqs(snap))
                                mask_ofl_test |= mask;
                        else

diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index 3556637768fd5316115cc5a55bcc92ea0e35d82e..250fbf2e8522f051480bd2c53ae97ab26dc098d8 100644 (file)
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -465,7 +465,7 @@ static void print_cpu_stall_info(int cpu)
        }
        delta = rcu_seq_ctr(rdp->mynode->gp_seq - rdp->rcu_iw_gp_seq);
        falsepositive = rcu_is_gp_kthread_starving(NULL) &&
-                       rcu_dynticks_in_eqs(rcu_dynticks_snap(rdp));
+                       rcu_dynticks_in_eqs(rcu_dynticks_snap(cpu));
        rcuc_starved = rcu_is_rcuc_kthread_starving(rdp, &j);
        if (rcuc_starved)
                sprintf(buf, " rcuc=%ld jiffies(starved)", j);
@@ -478,7 +478,7 @@ static void print_cpu_stall_info(int cpu)
                        rdp->rcu_iw_pending ? (int)min(delta, 9UL) + '0' :
                                "!."[!delta],
               ticks_value, ticks_title,
-              rcu_dynticks_snap(rdp) & 0xfff,
+              rcu_dynticks_snap(cpu) & 0xfff,
               rdp->dynticks_nesting, rdp->dynticks_nmi_nesting,
               rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu),
               data_race(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart,