diff options
Diffstat (limited to 'kernel/rcu/tree_exp.h')
| -rw-r--r-- | kernel/rcu/tree_exp.h | 53 |
1 files changed, 39 insertions, 14 deletions
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index 9c990df880d1..af7e7b9c86af 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -250,7 +250,7 @@ static void rcu_report_exp_cpu_mult(struct rcu_node *rnp, */ static void rcu_report_exp_rdp(struct rcu_data *rdp) { - WRITE_ONCE(rdp->deferred_qs, false); + WRITE_ONCE(rdp->exp_deferred_qs, false); rcu_report_exp_cpu_mult(rdp->mynode, rdp->grpmask, true); } @@ -259,8 +259,7 @@ static bool sync_exp_work_done(unsigned long s) { if (rcu_exp_gp_seq_done(s)) { trace_rcu_exp_grace_period(rcu_state.name, s, TPS("done")); - /* Ensure test happens before caller kfree(). */ - smp_mb__before_atomic(); /* ^^^ */ + smp_mb(); /* Ensure test happens before caller kfree(). */ return true; } return false; @@ -384,7 +383,12 @@ retry_ipi: mask_ofl_test |= mask; continue; } + if (get_cpu() == cpu) { + put_cpu(); + continue; + } ret = smp_call_function_single(cpu, rcu_exp_handler, NULL, 0); + put_cpu(); if (!ret) { mask_ofl_ipi &= ~mask; continue; @@ -611,7 +615,7 @@ static void rcu_exp_handler(void *unused) rcu_dynticks_curr_cpu_in_eqs()) { rcu_report_exp_rdp(rdp); } else { - rdp->deferred_qs = true; + rdp->exp_deferred_qs = true; set_tsk_need_resched(t); set_preempt_need_resched(); } @@ -633,7 +637,7 @@ static void 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) { - rdp->deferred_qs = true; + rdp->exp_deferred_qs = true; t->rcu_read_unlock_special.b.exp_hint = true; } raw_spin_unlock_irqrestore_rcu_node(rnp, flags); @@ -656,7 +660,7 @@ static void rcu_exp_handler(void *unused) * * Otherwise, force a context switch after the CPU enables everything. */ - rdp->deferred_qs = true; + rdp->exp_deferred_qs = true; if (!(preempt_count() & (PREEMPT_MASK | SOFTIRQ_MASK)) || WARN_ON_ONCE(rcu_dynticks_curr_cpu_in_eqs())) { rcu_preempt_deferred_qs(t); @@ -694,6 +698,16 @@ static int rcu_print_task_exp_stall(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) { @@ -709,25 +723,38 @@ static void rcu_exp_handler(void *unused) rcu_report_exp_rdp(this_cpu_ptr(&rcu_data)); return; } - __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(); + rcu_exp_need_qs(); } /* Send IPI for expedited cleanup if needed at end of CPU-hotplug operation. */ static void sync_sched_exp_online_cleanup(int cpu) { + unsigned long flags; + int my_cpu; struct rcu_data *rdp; int ret; struct rcu_node *rnp; rdp = per_cpu_ptr(&rcu_data, cpu); rnp = rdp->mynode; - if (!(READ_ONCE(rnp->expmask) & rdp->grpmask)) + my_cpu = get_cpu(); + /* Quiescent state either not needed or already requested, leave. */ + if (!(READ_ONCE(rnp->expmask) & rdp->grpmask) || + __this_cpu_read(rcu_data.cpu_no_qs.b.exp)) { + put_cpu(); + return; + } + /* Quiescent state needed on current CPU, so set it up locally. */ + if (my_cpu == cpu) { + local_irq_save(flags); + rcu_exp_need_qs(); + local_irq_restore(flags); + put_cpu(); return; + } + /* Quiescent state needed on some other CPU, send IPI. */ ret = smp_call_function_single(cpu, rcu_exp_handler, NULL, 0); + put_cpu(); WARN_ON_ONCE(ret); } @@ -765,7 +792,6 @@ static int rcu_print_task_exp_stall(struct rcu_node *rnp) */ void synchronize_rcu_expedited(void) { - struct rcu_data *rdp; struct rcu_exp_work rew; struct rcu_node *rnp; unsigned long s; @@ -802,7 +828,6 @@ void synchronize_rcu_expedited(void) } /* Wait for expedited grace period to complete. */ - rdp = per_cpu_ptr(&rcu_data, raw_smp_processor_id()); rnp = rcu_get_root(); wait_event(rnp->exp_wq[rcu_seq_ctr(s) & 0x3], sync_exp_work_done(s)); |