diff options
| -rw-r--r-- | include/linux/tick.h | 5 | ||||
| -rw-r--r-- | kernel/rcu/tree.h | 1 | ||||
| -rw-r--r-- | kernel/rcu/tree_exp.h | 52 |
3 files changed, 50 insertions, 8 deletions
diff --git a/include/linux/tick.h b/include/linux/tick.h index 7896f792d3b0..7340613c7eff 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -109,8 +109,10 @@ enum tick_dep_bits { TICK_DEP_BIT_PERF_EVENTS = 1, TICK_DEP_BIT_SCHED = 2, TICK_DEP_BIT_CLOCK_UNSTABLE = 3, - TICK_DEP_BIT_RCU = 4 + TICK_DEP_BIT_RCU = 4, + TICK_DEP_BIT_RCU_EXP = 5 }; +#define TICK_DEP_BIT_MAX TICK_DEP_BIT_RCU_EXP #define TICK_DEP_MASK_NONE 0 #define TICK_DEP_MASK_POSIX_TIMER (1 << TICK_DEP_BIT_POSIX_TIMER) @@ -118,6 +120,7 @@ enum tick_dep_bits { #define TICK_DEP_MASK_SCHED (1 << TICK_DEP_BIT_SCHED) #define TICK_DEP_MASK_CLOCK_UNSTABLE (1 << TICK_DEP_BIT_CLOCK_UNSTABLE) #define TICK_DEP_MASK_RCU (1 << TICK_DEP_BIT_RCU) +#define TICK_DEP_MASK_RCU_EXP (1 << TICK_DEP_BIT_RCU_EXP) #ifdef CONFIG_NO_HZ_COMMON extern bool tick_nohz_enabled; diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index 055c31781d3a..f9253ed406ba 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -182,6 +182,7 @@ struct rcu_data { bool rcu_need_heavy_qs; /* GP old, so heavy quiescent state! */ bool rcu_urgent_qs; /* GP old need light quiescent state. */ bool rcu_forced_tick; /* Forced tick to provide QS. */ + bool rcu_forced_tick_exp; /* ... provide QS to expedited GP. */ #ifdef CONFIG_RCU_FAST_NO_HZ bool all_lazy; /* All CPU's CBs lazy at idle start? */ unsigned long last_accelerate; /* Last jiffy CBs were accelerated. */ diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index 081a17942e57..30b2a02aef39 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -230,7 +230,9 @@ static void __maybe_unused rcu_report_exp_rnp(struct rcu_node *rnp, bool wake) static void rcu_report_exp_cpu_mult(struct rcu_node *rnp, unsigned long mask, bool wake) { + int cpu; unsigned long flags; + struct rcu_data *rdp; raw_spin_lock_irqsave_rcu_node(rnp, flags); if (!(rnp->expmask & mask)) { @@ -238,6 +240,13 @@ static void rcu_report_exp_cpu_mult(struct rcu_node *rnp, return; } WRITE_ONCE(rnp->expmask, rnp->expmask & ~mask); + for_each_leaf_node_cpu_mask(rnp, cpu, mask) { + rdp = per_cpu_ptr(&rcu_data, cpu); + if (!IS_ENABLED(CONFIG_NO_HZ_FULL) || !rdp->rcu_forced_tick_exp) + continue; + rdp->rcu_forced_tick_exp = false; + tick_dep_clear_cpu(cpu, TICK_DEP_BIT_RCU_EXP); + } __rcu_report_exp_rnp(rnp, wake, flags); /* Releases rnp->lock. */ } @@ -450,6 +459,26 @@ static void sync_rcu_exp_select_cpus(void) } /* + * Wait for the expedited grace period to elapse, within time limit. + * If the time limit is exceeded without the grace period elapsing, + * return false, otherwise return true. + */ +static bool synchronize_rcu_expedited_wait_once(long tlimit) +{ + int t; + struct rcu_node *rnp_root = rcu_get_root(); + + t = swait_event_timeout_exclusive(rcu_state.expedited_wq, + sync_rcu_exp_done_unlocked(rnp_root), + tlimit); + // Workqueues should not be signaled. + if (t > 0 || sync_rcu_exp_done_unlocked(rnp_root)) + return true; + WARN_ON(t < 0); /* workqueues should not be signaled. */ + return false; +} + +/* * Wait for the expedited grace period to elapse, issuing any needed * RCU CPU stall warnings along the way. */ @@ -460,22 +489,31 @@ static void synchronize_rcu_expedited_wait(void) unsigned long jiffies_start; unsigned long mask; int ndetected; + struct rcu_data *rdp; struct rcu_node *rnp; struct rcu_node *rnp_root = rcu_get_root(); - int ret; trace_rcu_exp_grace_period(rcu_state.name, rcu_exp_gp_seq_endval(), TPS("startwait")); jiffies_stall = rcu_jiffies_till_stall_check(); jiffies_start = jiffies; + if (IS_ENABLED(CONFIG_NO_HZ_FULL)) { + if (synchronize_rcu_expedited_wait_once(1)) + return; + rcu_for_each_leaf_node(rnp) { + for_each_leaf_node_cpu_mask(rnp, cpu, rnp->expmask) { + rdp = per_cpu_ptr(&rcu_data, cpu); + if (rdp->rcu_forced_tick_exp) + continue; + rdp->rcu_forced_tick_exp = true; + tick_dep_set_cpu(cpu, TICK_DEP_BIT_RCU_EXP); + } + } + WARN_ON_ONCE(1); + } for (;;) { - ret = swait_event_timeout_exclusive( - rcu_state.expedited_wq, - sync_rcu_exp_done_unlocked(rnp_root), - jiffies_stall); - if (ret > 0 || sync_rcu_exp_done_unlocked(rnp_root)) + if (synchronize_rcu_expedited_wait_once(jiffies_stall)) return; - WARN_ON(ret < 0); /* workqueues should not be signaled. */ if (rcu_cpu_stall_suppress) continue; panic_on_rcu_stall(); |