From 70f12f848d3e981479b4f6f751e73c14f7c13e5b Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Mon, 12 May 2008 21:21:05 +0200 Subject: [PATCH] rcu: add rcu_barrier_sched() and rcu_barrier_bh() Add rcu_barrier_sched() and rcu_barrier_bh(). With these in place, rcutorture no longer gives the occasional oops when repeatedly starting and stopping torturing rcu_bh. Also adds the API needed to flush out pre-existing call_rcu_sched() callbacks. Signed-off-by: Paul E. McKenney Signed-off-by: Mathieu Desnoyers Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- include/linux/rcupdate.h | 2 ++ kernel/rcupdate.c | 55 +++++++++++++++++++++++++++++++++++----- 2 files changed, 51 insertions(+), 6 deletions(-) diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 411969cb524..e8b4039cfb2 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -246,6 +246,8 @@ extern void call_rcu_bh(struct rcu_head *head, /* Exported common interfaces */ extern void synchronize_rcu(void); extern void rcu_barrier(void); +extern void rcu_barrier_bh(void); +extern void rcu_barrier_sched(void); /* Internal to kernel */ extern void rcu_init(void); diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c index a4e329d9288..4a74b8d48d9 100644 --- a/kernel/rcupdate.c +++ b/kernel/rcupdate.c @@ -45,6 +45,12 @@ #include #include +enum rcu_barrier { + RCU_BARRIER_STD, + RCU_BARRIER_BH, + RCU_BARRIER_SCHED, +}; + static DEFINE_PER_CPU(struct rcu_head, rcu_barrier_head) = {NULL}; static atomic_t rcu_barrier_cpu_count; static DEFINE_MUTEX(rcu_barrier_mutex); @@ -83,19 +89,30 @@ static void rcu_barrier_callback(struct rcu_head *notused) /* * Called with preemption disabled, and from cross-cpu IRQ context. */ -static void rcu_barrier_func(void *notused) +static void rcu_barrier_func(void *type) { int cpu = smp_processor_id(); struct rcu_head *head = &per_cpu(rcu_barrier_head, cpu); atomic_inc(&rcu_barrier_cpu_count); - call_rcu(head, rcu_barrier_callback); + switch ((enum rcu_barrier)type) { + case RCU_BARRIER_STD: + call_rcu(head, rcu_barrier_callback); + break; + case RCU_BARRIER_BH: + call_rcu_bh(head, rcu_barrier_callback); + break; + case RCU_BARRIER_SCHED: + call_rcu_sched(head, rcu_barrier_callback); + break; + } } -/** - * rcu_barrier - Wait until all the in-flight RCUs are complete. +/* + * Orchestrate the specified type of RCU barrier, waiting for all + * RCU callbacks of the specified type to complete. */ -void rcu_barrier(void) +static void _rcu_barrier(enum rcu_barrier type) { BUG_ON(in_interrupt()); /* Take cpucontrol mutex to protect against CPU hotplug */ @@ -111,13 +128,39 @@ void rcu_barrier(void) * until all the callbacks are queued. */ rcu_read_lock(); - on_each_cpu(rcu_barrier_func, NULL, 0, 1); + on_each_cpu(rcu_barrier_func, (void *)type, 0, 1); rcu_read_unlock(); wait_for_completion(&rcu_barrier_completion); mutex_unlock(&rcu_barrier_mutex); } + +/** + * rcu_barrier - Wait until all in-flight call_rcu() callbacks complete. + */ +void rcu_barrier(void) +{ + _rcu_barrier(RCU_BARRIER_STD); +} EXPORT_SYMBOL_GPL(rcu_barrier); +/** + * rcu_barrier_bh - Wait until all in-flight call_rcu_bh() callbacks complete. + */ +void rcu_barrier_bh(void) +{ + _rcu_barrier(RCU_BARRIER_BH); +} +EXPORT_SYMBOL_GPL(rcu_barrier_bh); + +/** + * rcu_barrier_sched - Wait for in-flight call_rcu_sched() callbacks. + */ +void rcu_barrier_sched(void) +{ + _rcu_barrier(RCU_BARRIER_SCHED); +} +EXPORT_SYMBOL_GPL(rcu_barrier_sched); + void __init rcu_init(void) { __rcu_init(); -- 2.41.1