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Commit 33f76148 authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Ingo Molnar
Browse files

rcu: Add CPU-offline processing for single-node configurations 



Add preemptable-RCU plugin to handle the CPU-offline
processing.

An additional plugin is forthcoming to handle multinode RCU
trees, but this current plugin works for configurations up to
32 CPUs (64 CPUs for 64-bit kernels).

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: akpm@linux-foundation.org
Cc: mathieu.desnoyers@polymtl.ca
Cc: josht@linux.vnet.ibm.com
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
LKML-Reference: <12511321213336-git-send-email->
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 7c614d64

kernel/rcutree.c

+2 −0
Original line number Diff line number Diff line
@@ -84,6 +84,7 @@ extern long rcu_batches_completed_sched(void); 
static void cpu_quiet_msk(unsigned long mask, struct rcu_state *rsp,

			  struct rcu_node *rnp, unsigned long flags);

static void cpu_quiet_msk_finish(struct rcu_state *rsp, unsigned long flags);

static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp);

static void __rcu_process_callbacks(struct rcu_state *rsp,

				    struct rcu_data *rdp);

static void __call_rcu(struct rcu_head *head,
@@ -920,6 +921,7 @@ static void rcu_offline_cpu(int cpu) 
{

	__rcu_offline_cpu(cpu, &rcu_sched_state);

	__rcu_offline_cpu(cpu, &rcu_bh_state);

	rcu_preempt_offline_cpu(cpu);

}



#else /* #ifdef CONFIG_HOTPLUG_CPU */

kernel/rcutree_plugin.h

+24 −0
Original line number Diff line number Diff line
@@ -259,6 +259,18 @@ static int rcu_preempted_readers(struct rcu_node *rnp) 
	return !list_empty(&rnp->blocked_tasks[rnp->gpnum & 0x1]);

}



#ifdef CONFIG_HOTPLUG_CPU



/*

 * Do CPU-offline processing for preemptable RCU.

 */

static void rcu_preempt_offline_cpu(int cpu)

{

	__rcu_offline_cpu(cpu, &rcu_preempt_state);

}



#endif /* #ifdef CONFIG_HOTPLUG_CPU */



/*

 * Check for a quiescent state from the current CPU.  When a task blocks,

 * the task is recorded in the corresponding CPU's rcu_node structure,
@@ -395,6 +407,18 @@ static int rcu_preempted_readers(struct rcu_node *rnp) 
	return 0;

}



#ifdef CONFIG_HOTPLUG_CPU



/*

 * Because preemptable RCU does not exist, it never needs CPU-offline

 * processing.

 */

static void rcu_preempt_offline_cpu(int cpu)

{

}



#endif /* #ifdef CONFIG_HOTPLUG_CPU */



/*

 * Because preemptable RCU does not exist, it never has any callbacks

 * to check.