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Commit 844ccdd7 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Eliminate rcu_irq_enter_disabled() 



Now that the irq path uses the rcu_nmi_{enter,exit}() algorithm,
rcu_irq_enter() and rcu_irq_exit() may be used from any context.  There is
thus no need for rcu_irq_enter_disabled() and for the checks using it.
This commit therefore eliminates rcu_irq_enter_disabled().

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 51a1fd30

include/linux/rcutiny.h

+0 −1
Original line number Diff line number Diff line
@@ -111,7 +111,6 @@ static inline void rcu_cpu_stall_reset(void) { } 
static inline void rcu_idle_enter(void) { }

static inline void rcu_idle_exit(void) { }

static inline void rcu_irq_enter(void) { }

static inline bool rcu_irq_enter_disabled(void) { return false; }

static inline void rcu_irq_exit_irqson(void) { }

static inline void rcu_irq_enter_irqson(void) { }

static inline void rcu_irq_exit(void) { }

include/linux/rcutree.h

+0 −1
Original line number Diff line number Diff line
@@ -85,7 +85,6 @@ void rcu_irq_enter(void); 
void rcu_irq_exit(void);

void rcu_irq_enter_irqson(void);

void rcu_irq_exit_irqson(void);

bool rcu_irq_enter_disabled(void);



void exit_rcu(void);

include/linux/tracepoint.h

+1 −4
Original line number Diff line number Diff line
@@ -137,11 +137,8 @@ extern void syscall_unregfunc(void); 
									\

		if (!(cond))						\

			return;						\

		if (rcucheck) {						\

			if (WARN_ON_ONCE(rcu_irq_enter_disabled()))	\

				return;					\

		if (rcucheck)						\

			rcu_irq_enter_irqson();				\

		}							\

		rcu_read_lock_sched_notrace();				\

		it_func_ptr = rcu_dereference_sched((tp)->funcs);	\

		if (it_func_ptr) {					\

kernel/rcu/tree.c

+2 −20
Original line number Diff line number Diff line
@@ -270,20 +270,6 @@ static DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = { 
	.dynticks = ATOMIC_INIT(RCU_DYNTICK_CTRL_CTR),

};



/*

 * There's a few places, currently just in the tracing infrastructure,

 * that uses rcu_irq_enter() to make sure RCU is watching. But there's

 * a small location where that will not even work. In those cases

 * rcu_irq_enter_disabled() needs to be checked to make sure rcu_irq_enter()

 * can be called.

 */

static DEFINE_PER_CPU(bool, disable_rcu_irq_enter);



bool rcu_irq_enter_disabled(void)

{

	return this_cpu_read(disable_rcu_irq_enter);

}



/*

 * Record entry into an extended quiescent state.  This is only to be

 * called when not already in an extended quiescent state.
@@ -792,10 +778,8 @@ static void rcu_eqs_enter_common(bool user) 
		do_nocb_deferred_wakeup(rdp);

	}

	rcu_prepare_for_idle();

	__this_cpu_inc(disable_rcu_irq_enter);

	rdtp->dynticks_nesting = 0; /* Breaks tracing momentarily. */

	rcu_dynticks_eqs_enter(); /* After this, tracing works again. */

	__this_cpu_dec(disable_rcu_irq_enter);

	rdtp->dynticks_nesting = 0;

	rcu_dynticks_eqs_enter();

	rcu_dynticks_task_enter();



	/*
@@ -1001,10 +985,8 @@ static void rcu_eqs_exit(bool user) 
	if (oldval) {

		rdtp->dynticks_nesting++;

	} else {

		__this_cpu_inc(disable_rcu_irq_enter);

		rcu_eqs_exit_common(1, user);

		rdtp->dynticks_nesting = 1;

		__this_cpu_dec(disable_rcu_irq_enter);

		WRITE_ONCE(rdtp->dynticks_nmi_nesting, DYNTICK_IRQ_NONIDLE);

	}

}

kernel/trace/trace.c

+0 −11
Original line number Diff line number Diff line
@@ -2682,17 +2682,6 @@ void __trace_stack(struct trace_array *tr, unsigned long flags, int skip, 
	if (unlikely(in_nmi()))

		return;



	/*

	 * It is possible that a function is being traced in a

	 * location that RCU is not watching. A call to

	 * rcu_irq_enter() will make sure that it is, but there's

	 * a few internal rcu functions that could be traced

	 * where that wont work either. In those cases, we just

	 * do nothing.

	 */

	if (unlikely(rcu_irq_enter_disabled()))

		return;



	rcu_irq_enter_irqson();

	__ftrace_trace_stack(buffer, flags, skip, pc, NULL);

	rcu_irq_exit_irqson();