diff options
| -rw-r--r-- | kernel/rcutree.c | 81 | ||||
| -rw-r--r-- | kernel/rcutree.h | 16 | ||||
| -rw-r--r-- | kernel/rcutree_plugin.h | 8 | ||||
| -rw-r--r-- | kernel/rcutree_trace.c | 4 |
4 files changed, 31 insertions, 78 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c index ccdc04c4798..669d7fe049d 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -67,9 +67,6 @@ static struct lock_class_key rcu_node_class[NUM_RCU_LVLS]; .gpnum = -300, \ .completed = -300, \ .onofflock = __RAW_SPIN_LOCK_UNLOCKED(&structname.onofflock), \ - .orphan_cbs_list = NULL, \ - .orphan_cbs_tail = &structname.orphan_cbs_list, \ - .orphan_qlen = 0, \ .fqslock = __RAW_SPIN_LOCK_UNLOCKED(&structname.fqslock), \ .n_force_qs = 0, \ .n_force_qs_ngp = 0, \ @@ -984,53 +981,31 @@ rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp) #ifdef CONFIG_HOTPLUG_CPU /* - * Move a dying CPU's RCU callbacks to the ->orphan_cbs_list for the - * specified flavor of RCU. The callbacks will be adopted by the next - * _rcu_barrier() invocation or by the CPU_DEAD notifier, whichever - * comes first. Because this is invoked from the CPU_DYING notifier, - * irqs are already disabled. + * Move a dying CPU's RCU callbacks to online CPU's callback list. + * Synchronization is not required because this function executes + * in stop_machine() context. */ -static void rcu_send_cbs_to_orphanage(struct rcu_state *rsp) +static void rcu_send_cbs_to_online(struct rcu_state *rsp) { int i; + /* current DYING CPU is cleared in the cpu_online_mask */ + int receive_cpu = cpumask_any(cpu_online_mask); struct rcu_data *rdp = this_cpu_ptr(rsp->rda); + struct rcu_data *receive_rdp = per_cpu_ptr(rsp->rda, receive_cpu); if (rdp->nxtlist == NULL) return; /* irqs disabled, so comparison is stable. */ - raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */ - *rsp->orphan_cbs_tail = rdp->nxtlist; - rsp->orphan_cbs_tail = rdp->nxttail[RCU_NEXT_TAIL]; + + *receive_rdp->nxttail[RCU_NEXT_TAIL] = rdp->nxtlist; + receive_rdp->nxttail[RCU_NEXT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; + receive_rdp->qlen += rdp->qlen; + receive_rdp->n_cbs_adopted += rdp->qlen; + rdp->n_cbs_orphaned += rdp->qlen; + rdp->nxtlist = NULL; for (i = 0; i < RCU_NEXT_SIZE; i++) rdp->nxttail[i] = &rdp->nxtlist; - rsp->orphan_qlen += rdp->qlen; - rdp->n_cbs_orphaned += rdp->qlen; rdp->qlen = 0; - raw_spin_unlock(&rsp->onofflock); /* irqs remain disabled. */ -} - -/* - * Adopt previously orphaned RCU callbacks. - */ -static void rcu_adopt_orphan_cbs(struct rcu_state *rsp) -{ - unsigned long flags; - struct rcu_data *rdp; - - raw_spin_lock_irqsave(&rsp->onofflock, flags); - rdp = this_cpu_ptr(rsp->rda); - if (rsp->orphan_cbs_list == NULL) { - raw_spin_unlock_irqrestore(&rsp->onofflock, flags); - return; - } - *rdp->nxttail[RCU_NEXT_TAIL] = rsp->orphan_cbs_list; - rdp->nxttail[RCU_NEXT_TAIL] = rsp->orphan_cbs_tail; - rdp->qlen += rsp->orphan_qlen; - rdp->n_cbs_adopted += rsp->orphan_qlen; - rsp->orphan_cbs_list = NULL; - rsp->orphan_cbs_tail = &rsp->orphan_cbs_list; - rsp->orphan_qlen = 0; - raw_spin_unlock_irqrestore(&rsp->onofflock, flags); } /* @@ -1081,8 +1056,6 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp) raw_spin_unlock_irqrestore(&rnp->lock, flags); if (need_report & RCU_OFL_TASKS_EXP_GP) rcu_report_exp_rnp(rsp, rnp); - - rcu_adopt_orphan_cbs(rsp); } /* @@ -1100,11 +1073,7 @@ static void rcu_offline_cpu(int cpu) #else /* #ifdef CONFIG_HOTPLUG_CPU */ -static void rcu_send_cbs_to_orphanage(struct rcu_state *rsp) -{ -} - -static void rcu_adopt_orphan_cbs(struct rcu_state *rsp) +static void rcu_send_cbs_to_online(struct rcu_state *rsp) { } @@ -1702,10 +1671,7 @@ static void _rcu_barrier(struct rcu_state *rsp, * early. */ atomic_set(&rcu_barrier_cpu_count, 1); - preempt_disable(); /* stop CPU_DYING from filling orphan_cbs_list */ - rcu_adopt_orphan_cbs(rsp); on_each_cpu(rcu_barrier_func, (void *)call_rcu_func, 1); - preempt_enable(); /* CPU_DYING can again fill orphan_cbs_list */ if (atomic_dec_and_test(&rcu_barrier_cpu_count)) complete(&rcu_barrier_completion); wait_for_completion(&rcu_barrier_completion); @@ -1831,18 +1797,13 @@ static int __cpuinit rcu_cpu_notify(struct notifier_block *self, case CPU_DYING: case CPU_DYING_FROZEN: /* - * preempt_disable() in _rcu_barrier() prevents stop_machine(), - * so when "on_each_cpu(rcu_barrier_func, (void *)type, 1);" - * returns, all online cpus have queued rcu_barrier_func(). - * The dying CPU clears its cpu_online_mask bit and - * moves all of its RCU callbacks to ->orphan_cbs_list - * in the context of stop_machine(), so subsequent calls - * to _rcu_barrier() will adopt these callbacks and only - * then queue rcu_barrier_func() on all remaining CPUs. + * The whole machine is "stopped" except this cpu, so we can + * touch any data without introducing corruption. And we send + * the callbacks to an attribute chosen online cpu. */ - rcu_send_cbs_to_orphanage(&rcu_bh_state); - rcu_send_cbs_to_orphanage(&rcu_sched_state); - rcu_preempt_send_cbs_to_orphanage(); + rcu_send_cbs_to_online(&rcu_bh_state); + rcu_send_cbs_to_online(&rcu_sched_state); + rcu_preempt_send_cbs_to_online(); break; case CPU_DEAD: case CPU_DEAD_FROZEN: diff --git a/kernel/rcutree.h b/kernel/rcutree.h index 91d4170c5c1..1a54be2a902 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -203,8 +203,8 @@ struct rcu_data { long qlen_last_fqs_check; /* qlen at last check for QS forcing */ unsigned long n_cbs_invoked; /* count of RCU cbs invoked. */ - unsigned long n_cbs_orphaned; /* RCU cbs sent to orphanage. */ - unsigned long n_cbs_adopted; /* RCU cbs adopted from orphanage. */ + unsigned long n_cbs_orphaned; /* RCU cbs orphaned by dying CPU */ + unsigned long n_cbs_adopted; /* RCU cbs adopted from dying CPU */ unsigned long n_force_qs_snap; /* did other CPU force QS recently? */ long blimit; /* Upper limit on a processed batch */ @@ -309,15 +309,7 @@ struct rcu_state { /* End of fields guarded by root rcu_node's lock. */ raw_spinlock_t onofflock; /* exclude on/offline and */ - /* starting new GP. Also */ - /* protects the following */ - /* orphan_cbs fields. */ - struct rcu_head *orphan_cbs_list; /* list of rcu_head structs */ - /* orphaned by all CPUs in */ - /* a given leaf rcu_node */ - /* going offline. */ - struct rcu_head **orphan_cbs_tail; /* And tail pointer. */ - long orphan_qlen; /* Number of orphaned cbs. */ + /* starting new GP. */ raw_spinlock_t fqslock; /* Only one task forcing */ /* quiescent states. */ unsigned long jiffies_force_qs; /* Time at which to invoke */ @@ -390,7 +382,7 @@ static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp); static int rcu_preempt_pending(int cpu); static int rcu_preempt_needs_cpu(int cpu); static void __cpuinit rcu_preempt_init_percpu_data(int cpu); -static void rcu_preempt_send_cbs_to_orphanage(void); +static void rcu_preempt_send_cbs_to_online(void); static void __init __rcu_init_preempt(void); static void rcu_needs_cpu_flush(void); diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index 21df7f3e727..0de359be5b4 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -774,11 +774,11 @@ static void __cpuinit rcu_preempt_init_percpu_data(int cpu) } /* - * Move preemptable RCU's callbacks to ->orphan_cbs_list. + * Move preemptable DYING RCU's callbacks to other online CPU. */ -static void rcu_preempt_send_cbs_to_orphanage(void) +static void rcu_preempt_send_cbs_to_online(void) { - rcu_send_cbs_to_orphanage(&rcu_preempt_state); + rcu_send_cbs_to_online(&rcu_preempt_state); } /* @@ -1002,7 +1002,7 @@ static void __cpuinit rcu_preempt_init_percpu_data(int cpu) /* * Because there is no preemptable RCU, there are no callbacks to move. */ -static void rcu_preempt_send_cbs_to_orphanage(void) +static void rcu_preempt_send_cbs_to_online(void) { } diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c index 78ad3c35b68..c8e97853b97 100644 --- a/kernel/rcutree_trace.c +++ b/kernel/rcutree_trace.c @@ -166,13 +166,13 @@ static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp) gpnum = rsp->gpnum; seq_printf(m, "c=%lu g=%lu s=%d jfq=%ld j=%x " - "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu oqlen=%ld\n", + "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu\n", rsp->completed, gpnum, rsp->signaled, (long)(rsp->jiffies_force_qs - jiffies), (int)(jiffies & 0xffff), rsp->n_force_qs, rsp->n_force_qs_ngp, rsp->n_force_qs - rsp->n_force_qs_ngp, - rsp->n_force_qs_lh, rsp->orphan_qlen); + rsp->n_force_qs_lh); for (rnp = &rsp->node[0]; rnp - &rsp->node[0] < NUM_RCU_NODES; rnp++) { if (rnp->level != level) { seq_puts(m, "\n"); |