diff options
| -rw-r--r-- | kernel/rcu/tree.c | 41 | ||||
| -rw-r--r-- | kernel/rcu/tree.h | 1 |
2 files changed, 15 insertions, 27 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index a2147d7b51c0..ae39a49daa58 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -103,6 +103,7 @@ struct rcu_state sname##_state = { \ .orphan_nxttail = &sname##_state.orphan_nxtlist, \ .orphan_donetail = &sname##_state.orphan_donelist, \ .barrier_mutex = __MUTEX_INITIALIZER(sname##_state.barrier_mutex), \ + .expedited_mutex = __MUTEX_INITIALIZER(sname##_state.expedited_mutex), \ .name = RCU_STATE_NAME(sname), \ .abbr = sabbr, \ } @@ -3305,8 +3306,6 @@ static int synchronize_sched_expedited_cpu_stop(void *data) */ void synchronize_sched_expedited(void) { - cpumask_var_t cm; - bool cma = false; int cpu; long firstsnap, s, snap; int trycount = 0; @@ -3342,28 +3341,11 @@ void synchronize_sched_expedited(void) } WARN_ON_ONCE(cpu_is_offline(raw_smp_processor_id())); - /* Offline CPUs, idle CPUs, and any CPU we run on are quiescent. */ - cma = zalloc_cpumask_var(&cm, GFP_KERNEL); - if (cma) { - cpumask_copy(cm, cpu_online_mask); - cpumask_clear_cpu(raw_smp_processor_id(), cm); - for_each_cpu(cpu, cm) { - struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu); - - if (!(atomic_add_return(0, &rdtp->dynticks) & 0x1)) - cpumask_clear_cpu(cpu, cm); - } - if (cpumask_weight(cm) == 0) - goto all_cpus_idle; - } - /* * Each pass through the following loop attempts to force a * context switch on each CPU. */ - while (try_stop_cpus(cma ? cm : cpu_online_mask, - synchronize_sched_expedited_cpu_stop, - NULL) == -EAGAIN) { + while (!mutex_trylock(&rsp->expedited_mutex)) { put_online_cpus(); atomic_long_inc(&rsp->expedited_tryfail); @@ -3373,7 +3355,6 @@ void synchronize_sched_expedited(void) /* ensure test happens before caller kfree */ smp_mb__before_atomic(); /* ^^^ */ atomic_long_inc(&rsp->expedited_workdone1); - free_cpumask_var(cm); return; } @@ -3383,7 +3364,6 @@ void synchronize_sched_expedited(void) } else { wait_rcu_gp(call_rcu_sched); atomic_long_inc(&rsp->expedited_normal); - free_cpumask_var(cm); return; } @@ -3393,7 +3373,6 @@ void synchronize_sched_expedited(void) /* ensure test happens before caller kfree */ smp_mb__before_atomic(); /* ^^^ */ atomic_long_inc(&rsp->expedited_workdone2); - free_cpumask_var(cm); return; } @@ -3408,16 +3387,23 @@ void synchronize_sched_expedited(void) /* CPU hotplug operation in flight, use normal GP. */ wait_rcu_gp(call_rcu_sched); atomic_long_inc(&rsp->expedited_normal); - free_cpumask_var(cm); return; } snap = atomic_long_read(&rsp->expedited_start); smp_mb(); /* ensure read is before try_stop_cpus(). */ } - atomic_long_inc(&rsp->expedited_stoppedcpus); -all_cpus_idle: - free_cpumask_var(cm); + /* Stop each CPU that is online, non-idle, and not us. */ + for_each_online_cpu(cpu) { + struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu); + + /* Skip our CPU and any idle CPUs. */ + if (raw_smp_processor_id() == cpu || + !(atomic_add_return(0, &rdtp->dynticks) & 0x1)) + continue; + stop_one_cpu(cpu, synchronize_sched_expedited_cpu_stop, NULL); + } + atomic_long_inc(&rsp->expedited_stoppedcpus); /* * Everyone up to our most recent fetch is covered by our grace @@ -3436,6 +3422,7 @@ all_cpus_idle: } } while (atomic_long_cmpxchg(&rsp->expedited_done, s, snap) != s); atomic_long_inc(&rsp->expedited_done_exit); + mutex_unlock(&rsp->expedited_mutex); put_online_cpus(); } diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index 7c0b09d754a1..7c25fe473ad9 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -480,6 +480,7 @@ struct rcu_state { /* _rcu_barrier(). */ /* End of fields guarded by barrier_mutex. */ + struct mutex expedited_mutex; /* Serializes expediting. */ atomic_long_t expedited_start; /* Starting ticket. */ atomic_long_t expedited_done; /* Done ticket. */ atomic_long_t expedited_wrap; /* # near-wrap incidents. */ |