From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932285AbZKNDvR (ORCPT ); Fri, 13 Nov 2009 22:51:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757338AbZKNDvP (ORCPT ); Fri, 13 Nov 2009 22:51:15 -0500 Received: from e3.ny.us.ibm.com ([32.97.182.143]:50634 "EHLO e3.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756782AbZKNDvP (ORCPT ); Fri, 13 Nov 2009 22:51:15 -0500 From: "Paul E. McKenney" 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" Subject: [PATCH tip/core/rcu 1/2] rcu: further cleanups of use of lastcomp Date: Fri, 13 Nov 2009 19:51:38 -0800 Message-Id: <1258170699933-git-send-email-> X-Mailer: git-send-email 1.5.2.5 In-Reply-To: <20091114035100.GA9599@linux.vnet.ibm.com> References: <20091114035100.GA9599@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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