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Commit 4c5273bf authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

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: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 2dba13f0

kernel/rcu/tree.c

+42 −37
Original line number Diff line number Diff line
@@ -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. */

kernel/rcu/tree.h

+0 −2
Original line number Diff line number Diff line
@@ -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. */

};

kernel/rcu/tree_plugin.h

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