diff options
| -rw-r--r-- | include/linux/sched.h | 4 | ||||
| -rw-r--r-- | kernel/rcu/tree_exp.h | 4 | ||||
| -rw-r--r-- | kernel/rcu/tree_plugin.h | 14 |
3 files changed, 17 insertions, 5 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index a51c13c2b1a0..e4c7b6241088 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -572,8 +572,10 @@ union rcu_special { struct { u8 blocked; u8 need_qs; + u8 exp_hint; /* Hint for performance. */ + u8 pad; /* No garbage from compiler! */ } b; /* Bits. */ - u16 s; /* Set of bits. */ + u32 s; /* Set of bits. */ }; enum perf_event_task_context { diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index e669ccf3751b..928fe5893a57 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -692,8 +692,10 @@ static void sync_rcu_exp_handler(void *unused) */ if (t->rcu_read_lock_nesting > 0) { raw_spin_lock_irqsave_rcu_node(rnp, flags); - if (rnp->expmask & rdp->grpmask) + if (rnp->expmask & rdp->grpmask) { rdp->deferred_qs = true; + WRITE_ONCE(t->rcu_read_unlock_special.b.exp_hint, true); + } raw_spin_unlock_irqrestore_rcu_node(rnp, flags); } diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 05915e536336..618956cc7a55 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -642,13 +642,21 @@ static void rcu_read_unlock_special(struct task_struct *t) local_irq_save(flags); irqs_were_disabled = irqs_disabled_flags(flags); - if ((preempt_bh_were_disabled || irqs_were_disabled) && - t->rcu_read_unlock_special.b.blocked) { + if (preempt_bh_were_disabled || irqs_were_disabled) { + WRITE_ONCE(t->rcu_read_unlock_special.b.exp_hint, false); /* Need to defer quiescent state until everything is enabled. */ - raise_softirq_irqoff(RCU_SOFTIRQ); + if (irqs_were_disabled) { + /* Enabling irqs does not reschedule, so... */ + raise_softirq_irqoff(RCU_SOFTIRQ); + } else { + /* Enabling BH or preempt does reschedule, so... */ + set_tsk_need_resched(current); + set_preempt_need_resched(); + } local_irq_restore(flags); return; } + WRITE_ONCE(t->rcu_read_unlock_special.b.exp_hint, false); rcu_preempt_deferred_qs_irqrestore(t, flags); } |