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rcu: Convert rcutree to hotplug state machine 

Straight forward conversion to the state machine. Though the question arises
whether this needs really all these state transitions to work.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160713153337.982013161@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Thomas Gleixner 2016-07-13 17:17:03 +00:00 committed by Ingo Molnar
parent 15d7e3d349
commit 4df8374254
5 changed files with 83 additions and 53 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/linux/cpuhotplug.h
View File

@ -20,11 +20,13 @@ enum cpuhp_state {
CPUHP_X2APIC_PREPARE,
CPUHP_SMPCFD_PREPARE,
CPUHP_TIMERS_DEAD,
CPUHP_RCUTREE_PREP,
CPUHP_NOTIFY_PREPARE,
CPUHP_BRINGUP_CPU,
CPUHP_AP_IDLE_DEAD,
CPUHP_AP_OFFLINE,
CPUHP_AP_SCHED_STARTING,
CPUHP_AP_RCUTREE_DYING,
CPUHP_AP_IRQ_GIC_STARTING,
CPUHP_AP_IRQ_GICV3_STARTING,
CPUHP_AP_IRQ_HIP04_STARTING,
@ -80,6 +82,7 @@ enum cpuhp_state {
CPUHP_AP_PERF_ARM_CCI_ONLINE,
CPUHP_AP_PERF_ARM_CCN_ONLINE,
CPUHP_AP_WORKQUEUE_ONLINE,
CPUHP_AP_RCUTREE_ONLINE,
CPUHP_AP_NOTIFY_ONLINE,
CPUHP_AP_ONLINE_DYN,
CPUHP_AP_ONLINE_DYN_END = CPUHP_AP_ONLINE_DYN + 30,

7
include/linux/rcutiny.h
View File

@ -243,4 +243,11 @@ static inline void rcu_all_qs(void)
barrier(); /* Avoid RCU read-side critical sections leaking across. */
}
/* RCUtree hotplug events */
#define rcutree_prepare_cpu NULL
#define rcutree_online_cpu NULL
#define rcutree_offline_cpu NULL
#define rcutree_dead_cpu NULL
#define rcutree_dying_cpu NULL
#endif /* __LINUX_RCUTINY_H */

7
include/linux/rcutree.h
View File

@ -111,4 +111,11 @@ bool rcu_is_watching(void);
void rcu_all_qs(void);
/* RCUtree hotplug events */
int rcutree_prepare_cpu(unsigned int cpu);
int rcutree_online_cpu(unsigned int cpu);
int rcutree_offline_cpu(unsigned int cpu);
int rcutree_dead_cpu(unsigned int cpu);
int rcutree_dying_cpu(unsigned int cpu);
#endif /* __LINUX_RCUTREE_H */

14
kernel/cpu.c
View File

@ -1205,6 +1205,11 @@ static struct cpuhp_step cpuhp_bp_states[] = {
.startup = NULL,
.teardown = timers_dead_cpu,
},
[CPUHP_RCUTREE_PREP] = {
.name = "RCU-tree prepare",
.startup = rcutree_prepare_cpu,
.teardown = rcutree_dead_cpu,
},
/*
* Preparatory and dead notifiers. Will be replaced once the notifiers
* are converted to states.
@ -1263,6 +1268,10 @@ static struct cpuhp_step cpuhp_ap_states[] = {
.startup = sched_cpu_starting,
.teardown = sched_cpu_dying,
},
[CPUHP_AP_RCUTREE_DYING] = {
.startup = NULL,
.teardown = rcutree_dying_cpu,
},
/*
* Low level startup/teardown notifiers. Run with interrupts
* disabled. Will be removed once the notifiers are converted to
@ -1296,6 +1305,11 @@ static struct cpuhp_step cpuhp_ap_states[] = {
.startup = workqueue_online_cpu,
.teardown = workqueue_offline_cpu,
},
[CPUHP_AP_RCUTREE_ONLINE] = {
.name = "RCU-tree online",
.startup = rcutree_online_cpu,
.teardown = rcutree_offline_cpu,
},
/*
* Online/down_prepare notifiers. Will be removed once the notifiers

105
kernel/rcu/tree.c
View File

@ -1073,11 +1073,11 @@ EXPORT_SYMBOL_GPL(rcu_is_watching);
* offline to continue to use RCU for one jiffy after marking itself
* offline in the cpu_online_mask. This leniency is necessary given the
* non-atomic nature of the online and offline processing, for example,
* the fact that a CPU enters the scheduler after completing the CPU_DYING
* notifiers.
* the fact that a CPU enters the scheduler after completing the teardown
* of the CPU.
*
* This is also why RCU internally marks CPUs online during the
* CPU_UP_PREPARE phase and offline during the CPU_DEAD phase.
* This is also why RCU internally marks CPUs online during in the
* preparation phase and offline after the CPU has been taken down.
*
* Disable checking if in an NMI handler because we cannot safely report
* errors from NMI handlers anyway.
@ -3806,12 +3806,58 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
}
static void rcu_prepare_cpu(int cpu)
int rcutree_prepare_cpu(unsigned int cpu)
{
struct rcu_state *rsp;
for_each_rcu_flavor(rsp)
rcu_init_percpu_data(cpu, rsp);
rcu_prepare_kthreads(cpu);
rcu_spawn_all_nocb_kthreads(cpu);
return 0;
}
static void rcutree_affinity_setting(unsigned int cpu, int outgoing)
{
struct rcu_data *rdp = per_cpu_ptr(rcu_state_p->rda, cpu);
rcu_boost_kthread_setaffinity(rdp->mynode, outgoing);
}
int rcutree_online_cpu(unsigned int cpu)
{
sync_sched_exp_online_cleanup(cpu);
rcutree_affinity_setting(cpu, -1);
return 0;
}
int rcutree_offline_cpu(unsigned int cpu)
{
rcutree_affinity_setting(cpu, cpu);
return 0;
}
int rcutree_dying_cpu(unsigned int cpu)
{
struct rcu_state *rsp;
for_each_rcu_flavor(rsp)
rcu_cleanup_dying_cpu(rsp);
return 0;
}
int rcutree_dead_cpu(unsigned int cpu)
{
struct rcu_state *rsp;
for_each_rcu_flavor(rsp) {
rcu_cleanup_dead_cpu(cpu, rsp);
do_nocb_deferred_wakeup(per_cpu_ptr(rsp->rda, cpu));
}
return 0;
}
#ifdef CONFIG_HOTPLUG_CPU
@ -3851,52 +3897,6 @@ void rcu_report_dead(unsigned int cpu)
}
#endif
/*
* Handle CPU online/offline notification events.
*/
int rcu_cpu_notify(struct notifier_block *self,
unsigned long action, void *hcpu)
{
long cpu = (long)hcpu;
struct rcu_data *rdp = per_cpu_ptr(rcu_state_p->rda, cpu);
struct rcu_node *rnp = rdp->mynode;
struct rcu_state *rsp;
switch (action) {
case CPU_UP_PREPARE:
case CPU_UP_PREPARE_FROZEN:
rcu_prepare_cpu(cpu);
rcu_prepare_kthreads(cpu);
rcu_spawn_all_nocb_kthreads(cpu);
break;
case CPU_ONLINE:
case CPU_DOWN_FAILED:
sync_sched_exp_online_cleanup(cpu);
rcu_boost_kthread_setaffinity(rnp, -1);
break;
case CPU_DOWN_PREPARE:
rcu_boost_kthread_setaffinity(rnp, cpu);
break;
case CPU_DYING:
case CPU_DYING_FROZEN:
for_each_rcu_flavor(rsp)
rcu_cleanup_dying_cpu(rsp);
break;
case CPU_DEAD:
case CPU_DEAD_FROZEN:
case CPU_UP_CANCELED:
case CPU_UP_CANCELED_FROZEN:
for_each_rcu_flavor(rsp) {
rcu_cleanup_dead_cpu(cpu, rsp);
do_nocb_deferred_wakeup(per_cpu_ptr(rsp->rda, cpu));
}
break;
default:
break;
}
return NOTIFY_OK;
}
static int rcu_pm_notify(struct notifier_block *self,
unsigned long action, void *hcpu)
{
@ -4208,10 +4208,9 @@ void __init rcu_init(void)
* this is called early in boot, before either interrupts
* or the scheduler are operational.
*/
cpu_notifier(rcu_cpu_notify, 0);
pm_notifier(rcu_pm_notify, 0);
for_each_online_cpu(cpu)
rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
rcutree_prepare_cpu(cpu);
}
#include "tree_exp.h"