From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca,
josh@joshtriplett.org, dvhltc@us.ibm.com, niv@us.ibm.com,
tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org,
Valdis.Kletnieks@vt.edu,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 3/3] Fix thinko in commit #de078d875, actually initialize full tree
Date: Fri, 18 Sep 2009 09:50:19 -0700 [thread overview]
Message-ID: <125329262011-git-send-email-> (raw)
In-Reply-To: <20090918164955.GA22272@linux.vnet.ibm.com>
From: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Commit #de078d875 repeatedly and incorrectly initializes the root rcu_node
structure's ->gpnum field rather than initializing the ->gpnum field of
each node in the tree. Fix this. Also add an additional consistency
check to catch this in the future.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcutree.c | 11 ++++-------
kernel/rcutree_plugin.h | 4 +++-
2 files changed, 7 insertions(+), 8 deletions(-)
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 30e0e91..dd6e743 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -596,8 +596,6 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
{
struct rcu_data *rdp = rsp->rda[smp_processor_id()];
struct rcu_node *rnp = rcu_get_root(rsp);
- struct rcu_node *rnp_cur;
- struct rcu_node *rnp_end;
if (!cpu_needs_another_gp(rsp, rdp)) {
spin_unlock_irqrestore(&rnp->lock, flags);
@@ -654,13 +652,12 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
* one corresponding to this CPU, due to the fact that we have
* irqs disabled.
*/
- rnp_end = &rsp->node[NUM_RCU_NODES];
- for (rnp_cur = &rsp->node[0]; rnp_cur < rnp_end; rnp_cur++) {
- spin_lock(&rnp_cur->lock); /* irqs already disabled. */
+ for (rnp = &rsp->node[0]; rnp < &rsp->node[NUM_RCU_NODES]; rnp++) {
+ spin_lock(&rnp->lock); /* irqs already disabled. */
rcu_preempt_check_blocked_tasks(rnp);
- rnp_cur->qsmask = rnp_cur->qsmaskinit;
+ rnp->qsmask = rnp->qsmaskinit;
rnp->gpnum = rsp->gpnum;
- spin_unlock(&rnp_cur->lock); /* irqs already disabled. */
+ spin_unlock(&rnp->lock); /* irqs already disabled. */
}
rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state now OK. */
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index a2d586c..55c6497 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -476,10 +476,12 @@ static void rcu_print_task_stall(struct rcu_node *rnp)
/*
* Because there is no preemptable RCU, there can be no readers blocked,
- * so there is no need to check for blocked tasks.
+ * so there is no need to check for blocked tasks. So check only for
+ * bogus qsmask values.
*/
static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp)
{
+ WARN_ON_ONCE(rnp->qsmask);
}
/*
--
1.5.2.5
next prev parent reply other threads:[~2009-09-18 16:50 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-18 16:49 [PATCH tip/core/rcu 0/3] Cleanups/bugfixes for large systems and TREE_PREEMPT_RCU Paul E. McKenney
2009-09-18 16:50 ` [PATCH tip/core/rcu 1/3] Add WARN_ON_ONCE() consistency checks covering state transitions Paul E. McKenney
2009-09-19 7:58 ` [tip:core/urgent] rcu: " tip-bot for Paul E. McKenney
2009-09-18 16:50 ` [PATCH tip/core/rcu 2/3] Apply results of code inspection of kernel/rcutree_plugin.h Paul E. McKenney
2009-09-18 16:58 ` Daniel Walker
2009-09-18 17:00 ` Peter Zijlstra
[not found] ` <1253293408.7060.47.camel@desktop>
2009-09-18 17:04 ` Peter Zijlstra
2009-09-18 17:08 ` Daniel Walker
2009-09-18 17:22 ` Paul E. McKenney
2009-09-18 17:56 ` Daniel Walker
2009-09-19 7:58 ` [tip:core/urgent] rcu: " tip-bot for Paul E. McKenney
2009-09-18 16:50 ` Paul E. McKenney [this message]
2009-09-19 7:59 ` [tip:core/urgent] rcu: Fix thinko, actually initialize full tree tip-bot for Paul E. McKenney
2009-09-19 6:55 ` [PATCH tip/core/rcu 0/3] Cleanups/bugfixes for large systems and TREE_PREEMPT_RCU Ingo Molnar
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