Commit 07325d4a authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Ingo Molnar
Browse files

rcu: Provide rcu_irq_exit_check_preempt() 



Provide a debug check which can be invoked from exception return to kernel
mode before an attempt is made to schedule. Warn if RCU is not ready for
this.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Cc: Paul E. McKenney <paulmck@kernel.org>
Link: https://lore.kernel.org/r/20200521202117.089709607@linutronix.de
parent aaf2bc50

include/linux/rcutiny.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -72,6 +72,7 @@ static inline void rcu_irq_exit_irqson(void) { } 
static inline void rcu_irq_enter_irqson(void) { }

static inline void rcu_irq_enter_irqson(void) { }

static inline void rcu_irq_exit(void) { }

static inline void rcu_irq_exit(void) { }

static inline void rcu_irq_exit_preempt(void) { }

static inline void rcu_irq_exit_preempt(void) { }

static inline void rcu_irq_exit_check_preempt(void) { }

static inline void exit_rcu(void) { }

static inline void exit_rcu(void) { }

static inline bool rcu_preempt_need_deferred_qs(struct task_struct *t)

static inline bool rcu_preempt_need_deferred_qs(struct task_struct *t)

{

{

include/linux/rcutree.h

+6 −0
Original line number Original line Diff line number Diff line
@@ -51,6 +51,12 @@ void rcu_irq_exit_preempt(void); 
void rcu_irq_enter_irqson(void);

void rcu_irq_enter_irqson(void);

void rcu_irq_exit_irqson(void);

void rcu_irq_exit_irqson(void);





#ifdef CONFIG_PROVE_RCU

void rcu_irq_exit_check_preempt(void);

#else

static inline void rcu_irq_exit_check_preempt(void) { }

#endif



void exit_rcu(void);

void exit_rcu(void);





void rcu_scheduler_starting(void);

void rcu_scheduler_starting(void);

kernel/rcu/tree.c

+18 −0
Original line number Original line Diff line number Diff line
@@ -765,6 +765,24 @@ void rcu_irq_exit_preempt(void) 
			 "RCU in extended quiescent state!");

			 "RCU in extended quiescent state!");

}

}





#ifdef CONFIG_PROVE_RCU

/**

 * rcu_irq_exit_check_preempt - Validate that scheduling is possible

 */

void rcu_irq_exit_check_preempt(void)

{

	lockdep_assert_irqs_disabled();



	RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nesting) <= 0,

			 "RCU dynticks_nesting counter underflow/zero!");

	RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nmi_nesting) !=

			 DYNTICK_IRQ_NONIDLE,

			 "Bad RCU  dynticks_nmi_nesting counter\n");

	RCU_LOCKDEP_WARN(rcu_dynticks_curr_cpu_in_eqs(),

			 "RCU in extended quiescent state!");

}

#endif /* #ifdef CONFIG_PROVE_RCU */



/*

/*

 * Wrapper for rcu_irq_exit() where interrupts are enabled.

 * Wrapper for rcu_irq_exit() where interrupts are enabled.

 *

 *

CRA Git | Maintained and supported by SUSTech CRA and CCSE