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, dhowells@redhat.com,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 1/2] rcu: further cleanups of use of lastcomp
Date: Fri, 13 Nov 2009 19:51:38 -0800 [thread overview]
Message-ID: <1258170699933-git-send-email-> (raw)
In-Reply-To: <20091114035100.GA9599@linux.vnet.ibm.com>
Now that a copy of the rsp->completed flag is available in all rcu_node
structures, make full use of it. It is still legitimate to access
rsp->completed while holding the root rcu_node structure's lock, however.
Also, tighten up force_quiescent_state()'s checks for end of current
grace period.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcutree.c | 13 ++++++-------
1 files changed, 6 insertions(+), 7 deletions(-)
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index f93f0e2..1089d08 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -817,7 +817,7 @@ cpu_quiet(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastcomp)
rnp = rdp->mynode;
spin_lock_irqsave(&rnp->lock, flags);
- if (lastcomp != ACCESS_ONCE(rsp->completed)) {
+ if (lastcomp != rnp->completed) {
/*
* Someone beat us to it for this grace period, so leave.
@@ -935,7 +935,6 @@ static void rcu_adopt_orphan_cbs(struct rcu_state *rsp)
static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
{
unsigned long flags;
- long lastcomp;
unsigned long mask;
struct rcu_data *rdp = rsp->rda[cpu];
struct rcu_node *rnp;
@@ -958,7 +957,6 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
spin_unlock(&rnp->lock); /* irqs remain disabled. */
rnp = rnp->parent;
} while (rnp != NULL);
- lastcomp = rsp->completed;
spin_unlock_irqrestore(&rsp->onofflock, flags);
@@ -1132,7 +1130,7 @@ static int rcu_process_dyntick(struct rcu_state *rsp, long lastcomp,
rcu_for_each_leaf_node(rsp, rnp) {
mask = 0;
spin_lock_irqsave(&rnp->lock, flags);
- if (rsp->completed != lastcomp) {
+ if (rnp->completed != lastcomp) {
spin_unlock_irqrestore(&rnp->lock, flags);
return 1;
}
@@ -1146,7 +1144,7 @@ static int rcu_process_dyntick(struct rcu_state *rsp, long lastcomp,
if ((rnp->qsmask & bit) != 0 && f(rsp->rda[cpu]))
mask |= bit;
}
- if (mask != 0 && rsp->completed == lastcomp) {
+ if (mask != 0 && rnp->completed == lastcomp) {
/* cpu_quiet_msk() releases rnp->lock. */
cpu_quiet_msk(mask, rsp, rnp, flags);
@@ -1183,7 +1181,7 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
lastcomp = rsp->gpnum - 1;
signaled = rsp->signaled;
rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS;
- if (lastcomp == rsp->gpnum) {
+ if(!rcu_gp_in_progress(rsp)) {
rsp->n_force_qs_ngp++;
spin_unlock(&rnp->lock);
goto unlock_ret; /* no GP in progress, time updated. */
@@ -1211,7 +1209,8 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
/* Update state, record completion counter. */
forcenow = 0;
spin_lock(&rnp->lock);
- if (lastcomp == rsp->completed &&
+ if (lastcomp + 1 == rsp->gpnum &&
+ lastcomp == rsp->completed &&
rsp->signaled == signaled) {
rsp->signaled = RCU_FORCE_QS;
rsp->completed_fqs = lastcomp;
--
1.5.2.5
next prev parent reply other threads:[~2009-11-14 3:51 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-14 3:51 [PATCH tip/core/rcu 0/2] rcu: lastcomp cleanups, fix rcu_pending() false positives Paul E. McKenney
2009-11-14 3:51 ` Paul E. McKenney [this message]
2009-11-14 10:18 ` [tip:core/rcu] rcu: Further cleanups of use of lastcomp tip-bot for Paul E. McKenney
2009-11-14 3:51 ` [PATCH tip/core/rcu 2/2] rcu: eliminate __rcu_pending() false positives Paul E. McKenney
2009-11-14 10:19 ` [tip:core/rcu] rcu: Eliminate " tip-bot for Paul E. McKenney
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