Commit 62e2412d authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Paul E. McKenney
Browse files

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: default avatarPaul E. McKenney <paulmck@kernel.org>
Signed-off-by: default avatarFrederic 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: default avatarPaul E. McKenney <paulmck@kernel.org>
Reviewed-by: default avatarNicolas Saenz Julienne <nsaenzju@redhat.com>
Tested-by: default avatarNicolas Saenz Julienne <nsaenzju@redhat.com>
parent 3864caaf

include/linux/context_tracking_state.h

+38 −7
Original line number Diff line number Diff line
@@ -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)

{

kernel/context_tracking.c

+7 −3
Original line number Diff line number Diff line
@@ -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;

kernel/rcu/tree.c

+27 −29
Original line number Diff line number Diff line
@@ -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;

kernel/rcu/tree.h

+0 −1
Original line number Diff line number Diff line
@@ -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. */

kernel/rcu/tree_exp.h

+1 −1
Original line number Diff line number Diff line
@@ -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