Commit 6ce75a23 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Introduce for_each_rcu_flavor() and use it 



The arrival of TREE_PREEMPT_RCU some years back included some ugly
code involving either #ifdef or #ifdef'ed wrapper functions to iterate
over all non-SRCU flavors of RCU.  This commit therefore introduces
a for_each_rcu_flavor() iterator over the rcu_state structures for each
flavor of RCU to clean up a bit of the ugliness.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 1bca8cf1

kernel/rcutree.c

+32 −21
Original line number Diff line number Diff line
@@ -84,6 +84,7 @@ struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh, call_rcu_bh); 
DEFINE_PER_CPU(struct rcu_data, rcu_bh_data);



static struct rcu_state *rcu_state;

LIST_HEAD(rcu_struct_flavors);



/* Increase (but not decrease) the CONFIG_RCU_FANOUT_LEAF at boot time. */

static int rcu_fanout_leaf = CONFIG_RCU_FANOUT_LEAF;
@@ -860,9 +861,10 @@ static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr) 
 */

void rcu_cpu_stall_reset(void)

{

	rcu_sched_state.jiffies_stall = jiffies + ULONG_MAX / 2;

	rcu_bh_state.jiffies_stall = jiffies + ULONG_MAX / 2;

	rcu_preempt_stall_reset();

	struct rcu_state *rsp;



	for_each_rcu_flavor(rsp)

		rsp->jiffies_stall = jiffies + ULONG_MAX / 2;

}



static struct notifier_block rcu_panic_block = {
@@ -1827,10 +1829,11 @@ __rcu_process_callbacks(struct rcu_state *rsp) 
 */

static void rcu_process_callbacks(struct softirq_action *unused)

{

	struct rcu_state *rsp;



	trace_rcu_utilization("Start RCU core");

	__rcu_process_callbacks(&rcu_sched_state);

	__rcu_process_callbacks(&rcu_bh_state);

	rcu_preempt_process_callbacks();

	for_each_rcu_flavor(rsp)

		__rcu_process_callbacks(rsp);

	trace_rcu_utilization("End RCU core");

}
@@ -2241,9 +2244,12 @@ static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp) 
 */

static int rcu_pending(int cpu)

{

	return __rcu_pending(&rcu_sched_state, &per_cpu(rcu_sched_data, cpu)) ||

	       __rcu_pending(&rcu_bh_state, &per_cpu(rcu_bh_data, cpu)) ||

	       rcu_preempt_pending(cpu);

	struct rcu_state *rsp;



	for_each_rcu_flavor(rsp)

		if (__rcu_pending(rsp, per_cpu_ptr(rsp->rda, cpu)))

			return 1;

	return 0;

}



/*
@@ -2253,10 +2259,13 @@ static int rcu_pending(int cpu) 
 */

static int rcu_cpu_has_callbacks(int cpu)

{

	struct rcu_state *rsp;



	/* RCU callbacks either ready or pending? */

	return per_cpu(rcu_sched_data, cpu).nxtlist ||

	       per_cpu(rcu_bh_data, cpu).nxtlist ||

	       rcu_preempt_cpu_has_callbacks(cpu);

	for_each_rcu_flavor(rsp)

		if (per_cpu_ptr(rsp->rda, cpu)->nxtlist)

			return 1;

	return 0;

}



/*
@@ -2551,9 +2560,11 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptible) 


static void __cpuinit rcu_prepare_cpu(int cpu)

{

	rcu_init_percpu_data(cpu, &rcu_sched_state, 0);

	rcu_init_percpu_data(cpu, &rcu_bh_state, 0);

	rcu_preempt_init_percpu_data(cpu);

	struct rcu_state *rsp;



	for_each_rcu_flavor(rsp)

		rcu_init_percpu_data(cpu, rsp,

				     strcmp(rsp->name, "rcu_preempt") == 0);

}



/*
@@ -2565,6 +2576,7 @@ static int __cpuinit rcu_cpu_notify(struct notifier_block *self, 
	long cpu = (long)hcpu;

	struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, cpu);

	struct rcu_node *rnp = rdp->mynode;

	struct rcu_state *rsp;



	trace_rcu_utilization("Start CPU hotplug");

	switch (action) {
@@ -2589,18 +2601,16 @@ static int __cpuinit rcu_cpu_notify(struct notifier_block *self, 
		 * touch any data without introducing corruption. We send the

		 * dying CPU's callbacks to an arbitrarily chosen online CPU.

		 */

		rcu_cleanup_dying_cpu(&rcu_bh_state);

		rcu_cleanup_dying_cpu(&rcu_sched_state);

		rcu_preempt_cleanup_dying_cpu();

		for_each_rcu_flavor(rsp)

			rcu_cleanup_dying_cpu(rsp);

		rcu_cleanup_after_idle(cpu);

		break;

	case CPU_DEAD:

	case CPU_DEAD_FROZEN:

	case CPU_UP_CANCELED:

	case CPU_UP_CANCELED_FROZEN:

		rcu_cleanup_dead_cpu(cpu, &rcu_bh_state);

		rcu_cleanup_dead_cpu(cpu, &rcu_sched_state);

		rcu_preempt_cleanup_dead_cpu(cpu);

		for_each_rcu_flavor(rsp)

			rcu_cleanup_dead_cpu(cpu, rsp);

		break;

	default:

		break;
@@ -2717,6 +2727,7 @@ static void __init rcu_init_one(struct rcu_state *rsp, 
		per_cpu_ptr(rsp->rda, i)->mynode = rnp;

		rcu_boot_init_percpu_data(i, rsp);

	}

	list_add(&rsp->flavors, &rcu_struct_flavors);

}



/*

kernel/rcutree.h

+5 −7
Original line number Diff line number Diff line
@@ -422,8 +422,13 @@ struct rcu_state { 
	unsigned long gp_max;			/* Maximum GP duration in */

						/*  jiffies. */

	char *name;				/* Name of structure. */

	struct list_head flavors;		/* List of RCU flavors. */

};



extern struct list_head rcu_struct_flavors;

#define for_each_rcu_flavor(rsp) \

	list_for_each_entry((rsp), &rcu_struct_flavors, flavors)



/* Return values for rcu_preempt_offline_tasks(). */



#define RCU_OFL_TASKS_NORM_GP	0x1		/* Tasks blocking normal */
@@ -466,25 +471,18 @@ static void rcu_stop_cpu_kthread(int cpu); 
#endif /* #ifdef CONFIG_HOTPLUG_CPU */

static void rcu_print_detail_task_stall(struct rcu_state *rsp);

static int rcu_print_task_stall(struct rcu_node *rnp);

static void rcu_preempt_stall_reset(void);

static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp);

#ifdef CONFIG_HOTPLUG_CPU

static int rcu_preempt_offline_tasks(struct rcu_state *rsp,

				     struct rcu_node *rnp,

				     struct rcu_data *rdp);

#endif /* #ifdef CONFIG_HOTPLUG_CPU */

static void rcu_preempt_cleanup_dead_cpu(int cpu);

static void rcu_preempt_check_callbacks(int cpu);

static void rcu_preempt_process_callbacks(void);

void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu));

#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU)

static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,

			       bool wake);

#endif /* #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU) */

static int rcu_preempt_pending(int cpu);

static int rcu_preempt_cpu_has_callbacks(int cpu);

static void __cpuinit rcu_preempt_init_percpu_data(int cpu);

static void rcu_preempt_cleanup_dying_cpu(void);

static void __init __rcu_init_preempt(void);

static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags);

static void rcu_preempt_boost_start_gp(struct rcu_node *rnp);

kernel/rcutree_plugin.h

+0 −116
Original line number Diff line number Diff line
@@ -544,16 +544,6 @@ static int rcu_print_task_stall(struct rcu_node *rnp) 
	return ndetected;

}



/*

 * Suppress preemptible RCU's CPU stall warnings by pushing the

 * time of the next stall-warning message comfortably far into the

 * future.

 */

static void rcu_preempt_stall_reset(void)

{

	rcu_preempt_state.jiffies_stall = jiffies + ULONG_MAX / 2;

}



/*

 * Check that the list of blocked tasks for the newly completed grace

 * period is in fact empty.  It is a serious bug to complete a grace
@@ -654,14 +644,6 @@ static int rcu_preempt_offline_tasks(struct rcu_state *rsp, 


#endif /* #ifdef CONFIG_HOTPLUG_CPU */



/*

 * Do CPU-offline processing for preemptible RCU.

 */

static void rcu_preempt_cleanup_dead_cpu(int cpu)

{

	rcu_cleanup_dead_cpu(cpu, &rcu_preempt_state);

}



/*

 * Check for a quiescent state from the current CPU.  When a task blocks,

 * the task is recorded in the corresponding CPU's rcu_node structure,
@@ -682,14 +664,6 @@ static void rcu_preempt_check_callbacks(int cpu) 
		t->rcu_read_unlock_special |= RCU_READ_UNLOCK_NEED_QS;

}



/*

 * Process callbacks for preemptible RCU.

 */

static void rcu_preempt_process_callbacks(void)

{

	__rcu_process_callbacks(&rcu_preempt_state);

}



#ifdef CONFIG_RCU_BOOST



static void rcu_preempt_do_callbacks(void)
@@ -921,24 +895,6 @@ mb_ret: 
}

EXPORT_SYMBOL_GPL(synchronize_rcu_expedited);



/*

 * Check to see if there is any immediate preemptible-RCU-related work

 * to be done.

 */

static int rcu_preempt_pending(int cpu)

{

	return __rcu_pending(&rcu_preempt_state,

			     &per_cpu(rcu_preempt_data, cpu));

}



/*

 * Does preemptible RCU have callbacks on this CPU?

 */

static int rcu_preempt_cpu_has_callbacks(int cpu)

{

	return !!per_cpu(rcu_preempt_data, cpu).nxtlist;

}



/**

 * rcu_barrier - Wait until all in-flight call_rcu() callbacks complete.

 */
@@ -948,23 +904,6 @@ void rcu_barrier(void) 
}

EXPORT_SYMBOL_GPL(rcu_barrier);



/*

 * Initialize preemptible RCU's per-CPU data.

 */

static void __cpuinit rcu_preempt_init_percpu_data(int cpu)

{

	rcu_init_percpu_data(cpu, &rcu_preempt_state, 1);

}



/*

 * Move preemptible RCU's callbacks from dying CPU to other online CPU

 * and record a quiescent state.

 */

static void rcu_preempt_cleanup_dying_cpu(void)

{

	rcu_cleanup_dying_cpu(&rcu_preempt_state);

}



/*

 * Initialize preemptible RCU's state structures.

 */
@@ -1049,14 +988,6 @@ static int rcu_print_task_stall(struct rcu_node *rnp) 
	return 0;

}



/*

 * Because preemptible RCU does not exist, there is no need to suppress

 * its CPU stall warnings.

 */

static void rcu_preempt_stall_reset(void)

{

}



/*

 * Because there is no preemptible RCU, there can be no readers blocked,

 * so there is no need to check for blocked tasks.  So check only for
@@ -1084,14 +1015,6 @@ static int rcu_preempt_offline_tasks(struct rcu_state *rsp, 


#endif /* #ifdef CONFIG_HOTPLUG_CPU */



/*

 * Because preemptible RCU does not exist, it never needs CPU-offline

 * processing.

 */

static void rcu_preempt_cleanup_dead_cpu(int cpu)

{

}



/*

 * Because preemptible RCU does not exist, it never has any callbacks

 * to check.
@@ -1100,14 +1023,6 @@ static void rcu_preempt_check_callbacks(int cpu) 
{

}



/*

 * Because preemptible RCU does not exist, it never has any callbacks

 * to process.

 */

static void rcu_preempt_process_callbacks(void)

{

}



/*

 * Queue an RCU callback for lazy invocation after a grace period.

 * This will likely be later named something like "call_rcu_lazy()",
@@ -1148,22 +1063,6 @@ static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp, 


#endif /* #ifdef CONFIG_HOTPLUG_CPU */



/*

 * Because preemptible RCU does not exist, it never has any work to do.

 */

static int rcu_preempt_pending(int cpu)

{

	return 0;

}



/*

 * Because preemptible RCU does not exist, it never has callbacks

 */

static int rcu_preempt_cpu_has_callbacks(int cpu)

{

	return 0;

}



/*

 * Because preemptible RCU does not exist, rcu_barrier() is just

 * another name for rcu_barrier_sched().
@@ -1174,21 +1073,6 @@ void rcu_barrier(void) 
}

EXPORT_SYMBOL_GPL(rcu_barrier);



/*

 * Because preemptible RCU does not exist, there is no per-CPU

 * data to initialize.

 */

static void __cpuinit rcu_preempt_init_percpu_data(int cpu)

{

}



/*

 * Because there is no preemptible RCU, there is no cleanup to do.

 */

static void rcu_preempt_cleanup_dying_cpu(void)

{

}



/*

 * Because preemptible RCU does not exist, it need not be initialized.

 */

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