diff options
| -rw-r--r-- | init/Kconfig | 12 | ||||
| -rw-r--r-- | kernel/rcutree.c | 21 | ||||
| -rw-r--r-- | kernel/rcutree.h | 6 |
3 files changed, 28 insertions, 11 deletions
diff --git a/init/Kconfig b/init/Kconfig index 4c93533da42..89e4cf672df 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -496,6 +496,12 @@ config RCU_USER_QS excluded from the global RCU state machine and thus doesn't to keep the timer tick on for RCU. + Unless you want to hack and help the development of the full + tickless feature, you shouldn't enable this option. It adds + unnecessary overhead. + + If unsure say N + config RCU_USER_QS_FORCE bool "Force userspace extended QS by default" depends on RCU_USER_QS @@ -504,6 +510,12 @@ config RCU_USER_QS_FORCE test this feature that treats userspace as an extended quiescent state until we have a real user like a full adaptive nohz option. + Unless you want to hack and help the development of the full + tickless feature, you shouldn't enable this option. It adds + unnecessary overhead. + + If unsure say N + config RCU_FANOUT int "Tree-based hierarchical RCU fanout value" range 2 64 if 64BIT diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 4fb2376ddf0..74df86bd920 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -74,6 +74,7 @@ static struct lock_class_key rcu_fqs_class[RCU_NUM_LVLS]; .orphan_nxttail = &sname##_state.orphan_nxtlist, \ .orphan_donetail = &sname##_state.orphan_donelist, \ .barrier_mutex = __MUTEX_INITIALIZER(sname##_state.barrier_mutex), \ + .onoff_mutex = __MUTEX_INITIALIZER(sname##_state.onoff_mutex), \ .name = #sname, \ } @@ -1197,7 +1198,7 @@ static int rcu_gp_init(struct rcu_state *rsp) raw_spin_unlock_irq(&rnp->lock); /* Exclude any concurrent CPU-hotplug operations. */ - get_online_cpus(); + mutex_lock(&rsp->onoff_mutex); /* * Set the quiescent-state-needed bits in all the rcu_node @@ -1234,7 +1235,7 @@ static int rcu_gp_init(struct rcu_state *rsp) cond_resched(); } - put_online_cpus(); + mutex_unlock(&rsp->onoff_mutex); return 1; } @@ -1700,6 +1701,7 @@ static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp) /* Remove the dead CPU from the bitmasks in the rcu_node hierarchy. */ /* Exclude any attempts to start a new grace period. */ + mutex_lock(&rsp->onoff_mutex); raw_spin_lock_irqsave(&rsp->onofflock, flags); /* Orphan the dead CPU's callbacks, and adopt them if appropriate. */ @@ -1744,6 +1746,7 @@ static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp) init_callback_list(rdp); /* Disallow further callbacks on this CPU. */ rdp->nxttail[RCU_NEXT_TAIL] = NULL; + mutex_unlock(&rsp->onoff_mutex); } #else /* #ifdef CONFIG_HOTPLUG_CPU */ @@ -2648,6 +2651,9 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptible) struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); struct rcu_node *rnp = rcu_get_root(rsp); + /* Exclude new grace periods. */ + mutex_lock(&rsp->onoff_mutex); + /* Set up local state, ensuring consistent view of global state. */ raw_spin_lock_irqsave(&rnp->lock, flags); rdp->beenonline = 1; /* We have now been online. */ @@ -2662,14 +2668,6 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptible) rcu_prepare_for_idle_init(cpu); raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ - /* - * A new grace period might start here. If so, we won't be part - * of it, but that is OK, as we are currently in a quiescent state. - */ - - /* Exclude any attempts to start a new GP on large systems. */ - raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */ - /* Add CPU to rcu_node bitmasks. */ rnp = rdp->mynode; mask = rdp->grpmask; @@ -2693,8 +2691,9 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptible) raw_spin_unlock(&rnp->lock); /* irqs already disabled. */ rnp = rnp->parent; } while (rnp != NULL && !(rnp->qsmaskinit & mask)); + local_irq_restore(flags); - raw_spin_unlock_irqrestore(&rsp->onofflock, flags); + mutex_unlock(&rsp->onoff_mutex); } static void __cpuinit rcu_prepare_cpu(int cpu) diff --git a/kernel/rcutree.h b/kernel/rcutree.h index 5faf05d6832..a240f032848 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -394,11 +394,17 @@ struct rcu_state { struct rcu_head **orphan_donetail; /* Tail of above. */ long qlen_lazy; /* Number of lazy callbacks. */ long qlen; /* Total number of callbacks. */ + /* End of fields guarded by onofflock. */ + + struct mutex onoff_mutex; /* Coordinate hotplug & GPs. */ + struct mutex barrier_mutex; /* Guards barrier fields. */ atomic_t barrier_cpu_count; /* # CPUs waiting on. */ struct completion barrier_completion; /* Wake at barrier end. */ unsigned long n_barrier_done; /* ++ at start and end of */ /* _rcu_barrier(). */ + /* End of fields guarded by barrier_mutex. */ + unsigned long jiffies_force_qs; /* Time at which to invoke */ /* force_quiescent_state(). */ unsigned long n_force_qs; /* Number of calls to */ |