Merge branch 'rcu/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/urgent
Pull low probability CONFIG_RCU_BOOST=y deadlock fix from Paul E. McKenney. Signed-off-by: Ingo Molnar <mingo@kernel.org>
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commit
40b3c43f04
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@ -705,7 +705,6 @@ static void stack_proc(void *arg)
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struct task_struct *from = current, *to = arg;
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to->thread.saved_task = from;
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rcu_switch_from(from);
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switch_to(from, to, from);
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}
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@ -184,7 +184,6 @@ static inline int rcu_preempt_depth(void)
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/* Internal to kernel */
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extern void rcu_sched_qs(int cpu);
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extern void rcu_bh_qs(int cpu);
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extern void rcu_preempt_note_context_switch(void);
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extern void rcu_check_callbacks(int cpu, int user);
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struct notifier_block;
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extern void rcu_idle_enter(void);
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@ -87,6 +87,10 @@ static inline void kfree_call_rcu(struct rcu_head *head,
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#ifdef CONFIG_TINY_RCU
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static inline void rcu_preempt_note_context_switch(void)
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{
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}
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static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
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{
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*delta_jiffies = ULONG_MAX;
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@ -95,6 +99,7 @@ static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
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#else /* #ifdef CONFIG_TINY_RCU */
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void rcu_preempt_note_context_switch(void);
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int rcu_preempt_needs_cpu(void);
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static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
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@ -108,6 +113,7 @@ static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
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static inline void rcu_note_context_switch(int cpu)
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{
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rcu_sched_qs(cpu);
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rcu_preempt_note_context_switch();
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}
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/*
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@ -1871,22 +1871,12 @@ static inline void rcu_copy_process(struct task_struct *p)
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INIT_LIST_HEAD(&p->rcu_node_entry);
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}
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static inline void rcu_switch_from(struct task_struct *prev)
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{
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if (prev->rcu_read_lock_nesting != 0)
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rcu_preempt_note_context_switch();
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}
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#else
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static inline void rcu_copy_process(struct task_struct *p)
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{
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}
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static inline void rcu_switch_from(struct task_struct *prev)
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{
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}
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#endif
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#ifdef CONFIG_SMP
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@ -201,6 +201,7 @@ void rcu_note_context_switch(int cpu)
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{
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trace_rcu_utilization("Start context switch");
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rcu_sched_qs(cpu);
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rcu_preempt_note_context_switch(cpu);
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trace_rcu_utilization("End context switch");
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}
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EXPORT_SYMBOL_GPL(rcu_note_context_switch);
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@ -444,6 +444,7 @@ DECLARE_PER_CPU(char, rcu_cpu_has_work);
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/* Forward declarations for rcutree_plugin.h */
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static void rcu_bootup_announce(void);
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long rcu_batches_completed(void);
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static void rcu_preempt_note_context_switch(int cpu);
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static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp);
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#ifdef CONFIG_HOTPLUG_CPU
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static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp,
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@ -153,7 +153,7 @@ static void rcu_preempt_qs(int cpu)
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*
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* Caller must disable preemption.
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*/
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void rcu_preempt_note_context_switch(void)
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static void rcu_preempt_note_context_switch(int cpu)
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{
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struct task_struct *t = current;
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unsigned long flags;
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@ -164,7 +164,7 @@ void rcu_preempt_note_context_switch(void)
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(t->rcu_read_unlock_special & RCU_READ_UNLOCK_BLOCKED) == 0) {
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/* Possibly blocking in an RCU read-side critical section. */
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rdp = __this_cpu_ptr(rcu_preempt_state.rda);
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rdp = per_cpu_ptr(rcu_preempt_state.rda, cpu);
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rnp = rdp->mynode;
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raw_spin_lock_irqsave(&rnp->lock, flags);
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t->rcu_read_unlock_special |= RCU_READ_UNLOCK_BLOCKED;
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@ -228,7 +228,7 @@ void rcu_preempt_note_context_switch(void)
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* means that we continue to block the current grace period.
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*/
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local_irq_save(flags);
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rcu_preempt_qs(smp_processor_id());
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rcu_preempt_qs(cpu);
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local_irq_restore(flags);
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}
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@ -1001,6 +1001,14 @@ void rcu_force_quiescent_state(void)
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}
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EXPORT_SYMBOL_GPL(rcu_force_quiescent_state);
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/*
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* Because preemptible RCU does not exist, we never have to check for
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* CPUs being in quiescent states.
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*/
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static void rcu_preempt_note_context_switch(int cpu)
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{
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}
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/*
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* Because preemptible RCU does not exist, there are never any preempted
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* RCU readers.
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@ -2081,7 +2081,6 @@ context_switch(struct rq *rq, struct task_struct *prev,
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#endif
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/* Here we just switch the register state and the stack. */
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rcu_switch_from(prev);
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switch_to(prev, next, prev);
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barrier();
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