Commit 7aeba709 authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Neeraj Upadhyay
Browse files

rcu/nocb: Introduce RCU_NOCB_LOCKDEP_WARN() 



Checking for races against concurrent (de-)offloading implies the
creation of !CONFIG_RCU_NOCB_CPU stubs to check if each relevant lock
is held. For now this only implies the nocb_lock but more are to be
expected.

Create instead a NOCB specific version of RCU_LOCKDEP_WARN() to avoid
the proliferation of stubs.

Signed-off-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Reviewed-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Signed-off-by: default avatarNeeraj Upadhyay <neeraj.upadhyay@kernel.org>
parent 8400291e

include/linux/rcupdate.h

+7 −0
Original line number Diff line number Diff line
@@ -144,11 +144,18 @@ void rcu_init_nohz(void); 
int rcu_nocb_cpu_offload(int cpu);

int rcu_nocb_cpu_deoffload(int cpu);

void rcu_nocb_flush_deferred_wakeup(void);



#define RCU_NOCB_LOCKDEP_WARN(c, s) RCU_LOCKDEP_WARN(c, s)



#else /* #ifdef CONFIG_RCU_NOCB_CPU */



static inline void rcu_init_nohz(void) { }

static inline int rcu_nocb_cpu_offload(int cpu) { return -EINVAL; }

static inline int rcu_nocb_cpu_deoffload(int cpu) { return 0; }

static inline void rcu_nocb_flush_deferred_wakeup(void) { }



#define RCU_NOCB_LOCKDEP_WARN(c, s)



#endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */



/*

kernel/rcu/tree_nocb.h

+0 −14
Original line number Diff line number Diff line
@@ -16,10 +16,6 @@ 
#ifdef CONFIG_RCU_NOCB_CPU

static cpumask_var_t rcu_nocb_mask; /* CPUs to have callbacks offloaded. */

static bool __read_mostly rcu_nocb_poll;    /* Offload kthread are to poll. */

static inline int rcu_lockdep_is_held_nocb(struct rcu_data *rdp)

{

	return lockdep_is_held(&rdp->nocb_lock);

}



static inline bool rcu_current_is_nocb_kthread(struct rcu_data *rdp)

{
@@ -1653,16 +1649,6 @@ static void show_rcu_nocb_state(struct rcu_data *rdp) 


#else /* #ifdef CONFIG_RCU_NOCB_CPU */



static inline int rcu_lockdep_is_held_nocb(struct rcu_data *rdp)

{

	return 0;

}



static inline bool rcu_current_is_nocb_kthread(struct rcu_data *rdp)

{

	return false;

}



/* No ->nocb_lock to acquire.  */

static void rcu_nocb_lock(struct rcu_data *rdp)

{

kernel/rcu/tree_plugin.h

+2 −2
Original line number Diff line number Diff line
@@ -24,10 +24,10 @@ static bool rcu_rdp_is_offloaded(struct rcu_data *rdp) 
	 * timers have their own means of synchronization against the

	 * offloaded state updaters.

	 */

	RCU_LOCKDEP_WARN(

	RCU_NOCB_LOCKDEP_WARN(

		!(lockdep_is_held(&rcu_state.barrier_mutex) ||

		  (IS_ENABLED(CONFIG_HOTPLUG_CPU) && lockdep_is_cpus_held()) ||

		  rcu_lockdep_is_held_nocb(rdp) ||

		  lockdep_is_held(&rdp->nocb_lock) ||

		  (!(IS_ENABLED(CONFIG_PREEMPT_COUNT) && preemptible()) &&

		   rdp == this_cpu_ptr(&rcu_data)) ||

		  rcu_current_is_nocb_kthread(rdp)),