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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2009-08-27 15:00:12 -0700
committerIngo Molnar <mingo@elte.hu>2009-08-29 15:34:40 +0200
commit868489660dabc0c28087cca3dbc1adbbc398c6fe (patch)
treecf991ec94ce29bccfef27213107748810c51a1ca
parentdd5d19bafd90d33043a4a14b2e2d98612caa293c (diff)
downloadop-kernel-dev-868489660dabc0c28087cca3dbc1adbbc398c6fe.zip
op-kernel-dev-868489660dabc0c28087cca3dbc1adbbc398c6fe.tar.gz
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: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Josh Triplett <josh@joshtriplett.org> Acked-by: Mathieu 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: Ingo Molnar <mingo@elte.hu>
-rw-r--r--include/linux/sched.h4
-rw-r--r--kernel/rcutree.c13
-rw-r--r--kernel/rcutree.h2
-rw-r--r--kernel/rcutree_plugin.h10
4 files changed, 17 insertions, 12 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 3fe0315..855fd0d 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -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 */
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index d903e2f..71bc797 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -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 ||
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index ca56036..bf8a6f9 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -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;
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index 04343be..4778936 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -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
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