Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU fixes from Ingo Molnar: "This tree includes a shutdown/cpu-hotplug deadlock fix and a documentation fix." * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: rcu: Advise most users not to enable RCU user mode rcu: Grace-period initialization excludes only RCU notifier
This commit is contained in:
Linus Torvalds
commit
9d55ab71b7
12
init/Kconfig
12
init/Kconfig
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@ -496,6 +496,12 @@ config RCU_USER_QS
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excluded from the global RCU state machine and thus doesn't
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to keep the timer tick on for RCU.
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Unless you want to hack and help the development of the full
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tickless feature, you shouldn't enable this option. It adds
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unnecessary overhead.
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If unsure say N
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config RCU_USER_QS_FORCE
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bool "Force userspace extended QS by default"
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depends on RCU_USER_QS
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@ -504,6 +510,12 @@ config RCU_USER_QS_FORCE
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test this feature that treats userspace as an extended quiescent
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state until we have a real user like a full adaptive nohz option.
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Unless you want to hack and help the development of the full
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tickless feature, you shouldn't enable this option. It adds
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unnecessary overhead.
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If unsure say N
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config RCU_FANOUT
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int "Tree-based hierarchical RCU fanout value"
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range 2 64 if 64BIT
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@ -74,6 +74,7 @@ static struct lock_class_key rcu_fqs_class[RCU_NUM_LVLS];
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.orphan_nxttail = &sname##_state.orphan_nxtlist, \
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.orphan_donetail = &sname##_state.orphan_donelist, \
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.barrier_mutex = __MUTEX_INITIALIZER(sname##_state.barrier_mutex), \
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.onoff_mutex = __MUTEX_INITIALIZER(sname##_state.onoff_mutex), \
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.name = #sname, \
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}
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@ -1197,7 +1198,7 @@ static int rcu_gp_init(struct rcu_state *rsp)
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raw_spin_unlock_irq(&rnp->lock);
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/* Exclude any concurrent CPU-hotplug operations. */
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get_online_cpus();
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mutex_lock(&rsp->onoff_mutex);
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/*
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* Set the quiescent-state-needed bits in all the rcu_node
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@ -1234,7 +1235,7 @@ static int rcu_gp_init(struct rcu_state *rsp)
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cond_resched();
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}
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put_online_cpus();
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mutex_unlock(&rsp->onoff_mutex);
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return 1;
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}
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@ -1700,6 +1701,7 @@ static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
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/* Remove the dead CPU from the bitmasks in the rcu_node hierarchy. */
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/* Exclude any attempts to start a new grace period. */
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mutex_lock(&rsp->onoff_mutex);
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raw_spin_lock_irqsave(&rsp->onofflock, flags);
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/* Orphan the dead CPU's callbacks, and adopt them if appropriate. */
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@ -1744,6 +1746,7 @@ static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
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init_callback_list(rdp);
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/* Disallow further callbacks on this CPU. */
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rdp->nxttail[RCU_NEXT_TAIL] = NULL;
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mutex_unlock(&rsp->onoff_mutex);
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}
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#else /* #ifdef CONFIG_HOTPLUG_CPU */
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@ -2648,6 +2651,9 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptible)
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struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
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struct rcu_node *rnp = rcu_get_root(rsp);
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/* Exclude new grace periods. */
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mutex_lock(&rsp->onoff_mutex);
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/* Set up local state, ensuring consistent view of global state. */
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raw_spin_lock_irqsave(&rnp->lock, flags);
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rdp->beenonline = 1; /* We have now been online. */
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@ -2662,14 +2668,6 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptible)
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rcu_prepare_for_idle_init(cpu);
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raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
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/*
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* A new grace period might start here. If so, we won't be part
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* of it, but that is OK, as we are currently in a quiescent state.
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*/
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/* Exclude any attempts to start a new GP on large systems. */
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raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */
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/* Add CPU to rcu_node bitmasks. */
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rnp = rdp->mynode;
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mask = rdp->grpmask;
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@ -2693,8 +2691,9 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptible)
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raw_spin_unlock(&rnp->lock); /* irqs already disabled. */
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rnp = rnp->parent;
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} while (rnp != NULL && !(rnp->qsmaskinit & mask));
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local_irq_restore(flags);
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raw_spin_unlock_irqrestore(&rsp->onofflock, flags);
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mutex_unlock(&rsp->onoff_mutex);
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}
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static void __cpuinit rcu_prepare_cpu(int cpu)
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@ -394,11 +394,17 @@ struct rcu_state {
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struct rcu_head **orphan_donetail; /* Tail of above. */
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long qlen_lazy; /* Number of lazy callbacks. */
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long qlen; /* Total number of callbacks. */
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/* End of fields guarded by onofflock. */
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struct mutex onoff_mutex; /* Coordinate hotplug & GPs. */
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struct mutex barrier_mutex; /* Guards barrier fields. */
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atomic_t barrier_cpu_count; /* # CPUs waiting on. */
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struct completion barrier_completion; /* Wake at barrier end. */
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unsigned long n_barrier_done; /* ++ at start and end of */
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/* _rcu_barrier(). */
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/* End of fields guarded by barrier_mutex. */
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unsigned long jiffies_force_qs; /* Time at which to invoke */
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/* force_quiescent_state(). */
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unsigned long n_force_qs; /* Number of calls to */
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