diff options
| -rw-r--r-- | kernel/rcu/tree.c | 123 | ||||
| -rw-r--r-- | kernel/rcu/tree.h | 1 |
2 files changed, 82 insertions, 42 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 6e92bf4337bd..d2cdcada6fe0 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3642,19 +3642,77 @@ static int synchronize_sched_expedited_cpu_stop(void *data) struct rcu_data *rdp = data; struct rcu_state *rsp = rdp->rsp; - /* We are here: If we are last, do the wakeup. */ - rdp->exp_done = true; - if (atomic_dec_and_test(&rsp->expedited_need_qs)) - wake_up(&rsp->expedited_wq); + /* Report the quiescent state. */ + rcu_report_exp_rdp(rsp, rdp, true); return 0; } +/* + * Select the nodes that the upcoming expedited grace period needs + * to wait for. + */ +static void sync_sched_exp_select_cpus(struct rcu_state *rsp) +{ + int cpu; + unsigned long flags; + unsigned long mask; + unsigned long mask_ofl_test; + unsigned long mask_ofl_ipi; + struct rcu_data *rdp; + struct rcu_node *rnp; + + sync_exp_reset_tree(rsp); + rcu_for_each_leaf_node(rsp, rnp) { + raw_spin_lock_irqsave(&rnp->lock, flags); + smp_mb__after_unlock_lock(); + + /* Each pass checks a CPU for identity, offline, and idle. */ + mask_ofl_test = 0; + for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++) { + struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); + struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu); + + if (raw_smp_processor_id() == cpu || + cpu_is_offline(cpu) || + !(atomic_add_return(0, &rdtp->dynticks) & 0x1)) + mask_ofl_test |= rdp->grpmask; + } + mask_ofl_ipi = rnp->expmask & ~mask_ofl_test; + + /* + * Need to wait for any blocked tasks as well. Note that + * additional blocking tasks will also block the expedited + * GP until such time as the ->expmask bits are cleared. + */ + if (rcu_preempt_has_tasks(rnp)) + rnp->exp_tasks = rnp->blkd_tasks.next; + raw_spin_unlock_irqrestore(&rnp->lock, flags); + + /* IPI the remaining CPUs for expedited quiescent state. */ + mask = 1; + for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask <<= 1) { + if (!(mask_ofl_ipi & mask)) + continue; + rdp = per_cpu_ptr(rsp->rda, cpu); + stop_one_cpu_nowait(cpu, synchronize_sched_expedited_cpu_stop, + rdp, &rdp->exp_stop_work); + mask_ofl_ipi &= ~mask; + } + /* Report quiescent states for those that went offline. */ + mask_ofl_test |= mask_ofl_ipi; + if (mask_ofl_test) + rcu_report_exp_cpu_mult(rsp, rnp, mask_ofl_test, false); + } +} + static void synchronize_sched_expedited_wait(struct rcu_state *rsp) { int cpu; unsigned long jiffies_stall; unsigned long jiffies_start; - struct rcu_data *rdp; + unsigned long mask; + struct rcu_node *rnp; + struct rcu_node *rnp_root = rcu_get_root(rsp); int ret; jiffies_stall = rcu_jiffies_till_stall_check(); @@ -3663,33 +3721,36 @@ static void synchronize_sched_expedited_wait(struct rcu_state *rsp) for (;;) { ret = wait_event_interruptible_timeout( rsp->expedited_wq, - !atomic_read(&rsp->expedited_need_qs), + sync_rcu_preempt_exp_done(rnp_root), jiffies_stall); if (ret > 0) return; if (ret < 0) { /* Hit a signal, disable CPU stall warnings. */ wait_event(rsp->expedited_wq, - !atomic_read(&rsp->expedited_need_qs)); + sync_rcu_preempt_exp_done(rnp_root)); return; } pr_err("INFO: %s detected expedited stalls on CPUs: {", rsp->name); - for_each_online_cpu(cpu) { - rdp = per_cpu_ptr(rsp->rda, cpu); - - if (rdp->exp_done) - continue; - pr_cont(" %d", cpu); + rcu_for_each_leaf_node(rsp, rnp) { + mask = 1; + for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask <<= 1) { + if (!(rnp->expmask & mask)) + continue; + pr_cont(" %d", cpu); + } + mask <<= 1; } pr_cont(" } %lu jiffies s: %lu\n", jiffies - jiffies_start, rsp->expedited_sequence); - for_each_online_cpu(cpu) { - rdp = per_cpu_ptr(rsp->rda, cpu); - - if (rdp->exp_done) - continue; - dump_cpu_task(cpu); + rcu_for_each_leaf_node(rsp, rnp) { + mask = 1; + for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask <<= 1) { + if (!(rnp->expmask & mask)) + continue; + dump_cpu_task(cpu); + } } jiffies_stall = 3 * rcu_jiffies_till_stall_check() + 3; } @@ -3713,7 +3774,6 @@ static void synchronize_sched_expedited_wait(struct rcu_state *rsp) */ void synchronize_sched_expedited(void) { - int cpu; unsigned long s; struct rcu_node *rnp; struct rcu_state *rsp = &rcu_sched_state; @@ -3736,27 +3796,8 @@ void synchronize_sched_expedited(void) } rcu_exp_gp_seq_start(rsp); - - /* Stop each CPU that is online, non-idle, and not us. */ - atomic_set(&rsp->expedited_need_qs, 1); /* Extra count avoids race. */ - for_each_online_cpu(cpu) { - struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); - struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu); - - rdp->exp_done = false; - - /* Skip our CPU and any idle CPUs. */ - if (raw_smp_processor_id() == cpu || - !(atomic_add_return(0, &rdtp->dynticks) & 0x1)) - continue; - atomic_inc(&rsp->expedited_need_qs); - stop_one_cpu_nowait(cpu, synchronize_sched_expedited_cpu_stop, - rdp, &rdp->exp_stop_work); - } - - /* Remove extra count and, if necessary, wait for CPUs to stop. */ - if (!atomic_dec_and_test(&rsp->expedited_need_qs)) - synchronize_sched_expedited_wait(rsp); + sync_sched_exp_select_cpus(rsp); + synchronize_sched_expedited_wait(rsp); rcu_exp_gp_seq_end(rsp); mutex_unlock(&rnp->exp_funnel_mutex); diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index a57f25ecca58..efe361c764ab 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -383,7 +383,6 @@ struct rcu_data { struct rcu_head oom_head; #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */ struct mutex exp_funnel_mutex; - bool exp_done; /* Expedited QS for this CPU? */ /* 7) Callback offloading. */ #ifdef CONFIG_RCU_NOCB_CPU |