diff options
Diffstat (limited to 'kernel/rcu/tree_exp.h')
| -rw-r--r-- | kernel/rcu/tree_exp.h | 78 |
1 files changed, 50 insertions, 28 deletions
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index fb664d3a01c9..8d4895c854c5 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -227,20 +227,22 @@ static void __maybe_unused rcu_report_exp_rnp(struct rcu_node *rnp, bool wake) /* * Report expedited quiescent state for multiple CPUs, all covered by the - * specified leaf rcu_node structure. + * specified leaf rcu_node structure, which is acquired by the caller. */ -static void rcu_report_exp_cpu_mult(struct rcu_node *rnp, - unsigned long mask, bool wake) +static void rcu_report_exp_cpu_mult(struct rcu_node *rnp, unsigned long flags, + unsigned long mask_in, bool wake) + __releases(rnp->lock) { int cpu; - unsigned long flags; + unsigned long mask; struct rcu_data *rdp; - raw_spin_lock_irqsave_rcu_node(rnp, flags); - if (!(rnp->expmask & mask)) { + raw_lockdep_assert_held_rcu_node(rnp); + if (!(rnp->expmask & mask_in)) { raw_spin_unlock_irqrestore_rcu_node(rnp, flags); return; } + mask = mask_in & rnp->expmask; WRITE_ONCE(rnp->expmask, rnp->expmask & ~mask); for_each_leaf_node_cpu_mask(rnp, cpu, mask) { rdp = per_cpu_ptr(&rcu_data, cpu); @@ -257,8 +259,13 @@ static void rcu_report_exp_cpu_mult(struct rcu_node *rnp, */ static void rcu_report_exp_rdp(struct rcu_data *rdp) { + unsigned long flags; + struct rcu_node *rnp = rdp->mynode; + + raw_spin_lock_irqsave_rcu_node(rnp, flags); WRITE_ONCE(rdp->cpu_no_qs.b.exp, false); - rcu_report_exp_cpu_mult(rdp->mynode, rdp->grpmask, true); + ASSERT_EXCLUSIVE_WRITER(rdp->cpu_no_qs.b.exp); + rcu_report_exp_cpu_mult(rnp, flags, rdp->grpmask, true); } /* Common code for work-done checking. */ @@ -432,8 +439,10 @@ retry_ipi: raw_spin_unlock_irqrestore_rcu_node(rnp, flags); } /* Report quiescent states for those that went offline. */ - if (mask_ofl_test) - rcu_report_exp_cpu_mult(rnp, mask_ofl_test, false); + if (mask_ofl_test) { + raw_spin_lock_irqsave_rcu_node(rnp, flags); + rcu_report_exp_cpu_mult(rnp, flags, mask_ofl_test, false); + } } static void rcu_exp_sel_wait_wake(unsigned long s); @@ -712,6 +721,18 @@ static void rcu_exp_sel_wait_wake(unsigned long s) rcu_exp_wait_wake(s); } +/* Request an expedited quiescent state. */ +static void rcu_exp_need_qs(void) +{ + lockdep_assert_irqs_disabled(); + ASSERT_EXCLUSIVE_WRITER_SCOPED(*this_cpu_ptr(&rcu_data.cpu_no_qs.b.exp)); + __this_cpu_write(rcu_data.cpu_no_qs.b.exp, true); + /* Store .exp before .rcu_urgent_qs. */ + smp_store_release(this_cpu_ptr(&rcu_data.rcu_urgent_qs), true); + set_tsk_need_resched(current); + set_preempt_need_resched(); +} + #ifdef CONFIG_PREEMPT_RCU /* @@ -730,24 +751,34 @@ static void rcu_exp_handler(void *unused) struct task_struct *t = current; /* - * First, the common case of not being in an RCU read-side + * First, is there no need for a quiescent state from this CPU, + * or is this CPU already looking for a quiescent state for the + * current grace period? If either is the case, just leave. + * However, this should not happen due to the preemptible + * sync_sched_exp_online_cleanup() implementation being a no-op, + * so warn if this does happen. + */ + ASSERT_EXCLUSIVE_WRITER_SCOPED(rdp->cpu_no_qs.b.exp); + if (WARN_ON_ONCE(!(READ_ONCE(rnp->expmask) & rdp->grpmask) || + READ_ONCE(rdp->cpu_no_qs.b.exp))) + return; + + /* + * Second, the common case of not being in an RCU read-side * critical section. If also enabled or idle, immediately * report the quiescent state, otherwise defer. */ if (!depth) { if (!(preempt_count() & (PREEMPT_MASK | SOFTIRQ_MASK)) || - rcu_is_cpu_rrupt_from_idle()) { + rcu_is_cpu_rrupt_from_idle()) rcu_report_exp_rdp(rdp); - } else { - WRITE_ONCE(rdp->cpu_no_qs.b.exp, true); - set_tsk_need_resched(t); - set_preempt_need_resched(); - } + else + rcu_exp_need_qs(); return; } /* - * Second, the less-common case of being in an RCU read-side + * Third, the less-common case of being in an RCU read-side * critical section. In this case we can count on a future * rcu_read_unlock(). However, this rcu_read_unlock() might * execute on some other CPU, but in that case there will be @@ -768,7 +799,7 @@ static void rcu_exp_handler(void *unused) return; } - // Finally, negative nesting depth should not happen. + // Fourth and finally, negative nesting depth should not happen. WARN_ON_ONCE(1); } @@ -835,16 +866,6 @@ static void rcu_exp_print_detail_task_stall_rnp(struct rcu_node *rnp) #else /* #ifdef CONFIG_PREEMPT_RCU */ -/* Request an expedited quiescent state. */ -static void rcu_exp_need_qs(void) -{ - __this_cpu_write(rcu_data.cpu_no_qs.b.exp, true); - /* Store .exp before .rcu_urgent_qs. */ - smp_store_release(this_cpu_ptr(&rcu_data.rcu_urgent_qs), true); - set_tsk_need_resched(current); - set_preempt_need_resched(); -} - /* Invoked on each online non-idle CPU for expedited quiescent state. */ static void rcu_exp_handler(void *unused) { @@ -852,6 +873,7 @@ static void rcu_exp_handler(void *unused) struct rcu_node *rnp = rdp->mynode; bool preempt_bh_enabled = !(preempt_count() & (PREEMPT_MASK | SOFTIRQ_MASK)); + ASSERT_EXCLUSIVE_WRITER_SCOPED(rdp->cpu_no_qs.b.exp); if (!(READ_ONCE(rnp->expmask) & rdp->grpmask) || __this_cpu_read(rcu_data.cpu_no_qs.b.exp)) return; |