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Commit 86848966 authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Ingo Molnar
Browse files

rcu: Changes from reviews: avoid casts, fix/add warnings, improve comments 



Changes suggested by review comments from Josh Triplett and
Mathieu Desnoyers.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: default avatarJosh Triplett <josh@joshtriplett.org>
Acked-by: default avatarMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: akpm@linux-foundation.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
LKML-Reference: <20090827220012.GA30525@linux.vnet.ibm.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent dd5d19ba

include/linux/sched.h

+3 −1
Original line number Diff line number Diff line
@@ -1163,6 +1163,8 @@ struct sched_rt_entity { 
#endif

};



struct rcu_node;



struct task_struct {

	volatile long state;	/* -1 unrunnable, 0 runnable, >0 stopped */

	void *stack;
@@ -1208,7 +1210,7 @@ struct task_struct { 
#ifdef CONFIG_TREE_PREEMPT_RCU

	int rcu_read_lock_nesting;

	char rcu_read_unlock_special;

	void *rcu_blocked_node;

	struct rcu_node *rcu_blocked_node;

	struct list_head rcu_node_entry;

#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */

kernel/rcutree.c

+6 −7
Original line number Diff line number Diff line
@@ -229,7 +229,6 @@ static int rcu_implicit_offline_qs(struct rcu_data *rdp) 
#endif /* #ifdef CONFIG_SMP */



#ifdef CONFIG_NO_HZ

static DEFINE_RATELIMIT_STATE(rcu_rs, 10 * HZ, 5);



/**

 * rcu_enter_nohz - inform RCU that current CPU is entering nohz
@@ -249,7 +248,7 @@ void rcu_enter_nohz(void) 
	rdtp = &__get_cpu_var(rcu_dynticks);

	rdtp->dynticks++;

	rdtp->dynticks_nesting--;

	WARN_ON_RATELIMIT(rdtp->dynticks & 0x1, &rcu_rs);

	WARN_ON_ONCE(rdtp->dynticks & 0x1);

	local_irq_restore(flags);

}
@@ -268,7 +267,7 @@ void rcu_exit_nohz(void) 
	rdtp = &__get_cpu_var(rcu_dynticks);

	rdtp->dynticks++;

	rdtp->dynticks_nesting++;

	WARN_ON_RATELIMIT(!(rdtp->dynticks & 0x1), &rcu_rs);

	WARN_ON_ONCE(!(rdtp->dynticks & 0x1));

	local_irq_restore(flags);

	smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */

}
@@ -287,7 +286,7 @@ void rcu_nmi_enter(void) 
	if (rdtp->dynticks & 0x1)

		return;

	rdtp->dynticks_nmi++;

	WARN_ON_RATELIMIT(!(rdtp->dynticks_nmi & 0x1), &rcu_rs);

	WARN_ON_ONCE(!(rdtp->dynticks_nmi & 0x1));

	smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */

}
@@ -306,7 +305,7 @@ void rcu_nmi_exit(void) 
		return;

	smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */

	rdtp->dynticks_nmi++;

	WARN_ON_RATELIMIT(rdtp->dynticks_nmi & 0x1, &rcu_rs);

	WARN_ON_ONCE(rdtp->dynticks_nmi & 0x1);

}



/**
@@ -322,7 +321,7 @@ void rcu_irq_enter(void) 
	if (rdtp->dynticks_nesting++)

		return;

	rdtp->dynticks++;

	WARN_ON_RATELIMIT(!(rdtp->dynticks & 0x1), &rcu_rs);

	WARN_ON_ONCE(!(rdtp->dynticks & 0x1));

	smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */

}
@@ -341,7 +340,7 @@ void rcu_irq_exit(void) 
		return;

	smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */

	rdtp->dynticks++;

	WARN_ON_RATELIMIT(rdtp->dynticks & 0x1, &rcu_rs);

	WARN_ON_ONCE(rdtp->dynticks & 0x1);



	/* If the interrupt queued a callback, get out of dyntick mode. */

	if (__get_cpu_var(rcu_sched_data).nxtlist ||

kernel/rcutree.h

+2 −0
Original line number Diff line number Diff line
@@ -81,6 +81,8 @@ struct rcu_dynticks { 
struct rcu_node {

	spinlock_t lock;

	long	gpnum;		/* Current grace period for this node. */

				/*  This will either be equal to or one */

				/*  behind the root rcu_node's gpnum. */

	unsigned long qsmask;	/* CPUs or groups that need to switch in */

				/*  order for current grace period to proceed.*/

	unsigned long qsmaskinit;

kernel/rcutree_plugin.h

+6 −4
Original line number Diff line number Diff line
@@ -92,7 +92,7 @@ static void rcu_preempt_qs(int cpu) 
		rnp = rdp->mynode;

		spin_lock(&rnp->lock);

		t->rcu_read_unlock_special |= RCU_READ_UNLOCK_BLOCKED;

		t->rcu_blocked_node = (void *)rnp;

		t->rcu_blocked_node = rnp;



		/*

		 * If this CPU has already checked in, then this task
@@ -176,9 +176,9 @@ static void rcu_read_unlock_special(struct task_struct *t) 
		 * most one time.  So at most two passes through loop.

		 */

		for (;;) {

			rnp = (struct rcu_node *)t->rcu_blocked_node;

			rnp = t->rcu_blocked_node;

			spin_lock(&rnp->lock);

			if (rnp == (struct rcu_node *)t->rcu_blocked_node)

			if (rnp == t->rcu_blocked_node)

				break;

			spin_unlock(&rnp->lock);

		}
@@ -288,8 +288,10 @@ static void rcu_preempt_offline_tasks(struct rcu_state *rsp, 
	struct rcu_node *rnp_root = rcu_get_root(rsp);

	struct task_struct *tp;



	if (rnp == rnp_root)

	if (rnp == rnp_root) {

		WARN_ONCE(1, "Last CPU thought to be offlined?");

		return;  /* Shouldn't happen: at least one CPU online. */

	}



	/*

	 * Move tasks up to root rcu_node.  Rely on the fact that the