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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2010-01-04 15:09:01 -0800
committerIngo Molnar <mingo@elte.hu>2010-01-13 09:06:01 +0100
commit559569acf94f538b56bd6eead80b439d6a78cdff (patch)
tree36ff850b4bfd45cdeb102092f4cf00c48ca86434 /kernel/rcutree.c
parentf96e9232e04856c781d4f71923a46dd3f7b429fa (diff)
downloadblackbird-op-linux-559569acf94f538b56bd6eead80b439d6a78cdff.tar.gz
blackbird-op-linux-559569acf94f538b56bd6eead80b439d6a78cdff.zip
rcu: Adjust force_quiescent_state() locking, step 2
This patch releases rnp->lock after the end of force_quiescent_state()'s switch statement. This is a second step towards prohibiting starting grace periods while force_quiescent_state() is executing, which will reduce the number and complexity of races that force_quiescent_state() is involved in. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <12626465501994-git-send-email-> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/rcutree.c')
-rw-r--r--kernel/rcutree.c13
1 files changed, 3 insertions, 10 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index eae331da6bee..d42ad30c4d70 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1219,7 +1219,6 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
case RCU_GP_IDLE:
case RCU_GP_INIT:
- spin_unlock(&rnp->lock);
break; /* grace period idle or initializing, ignore. */
case RCU_SAVE_DYNTICK:
@@ -1246,10 +1245,8 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
rsp->completed_fqs = lastcomp;
forcenow = signaled == RCU_SAVE_COMPLETED;
}
- if (!forcenow) {
- spin_unlock(&rnp->lock);
+ if (!forcenow)
break;
- }
/* fall into next case. */
case RCU_FORCE_QS:
@@ -1262,14 +1259,10 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
/* Leave state in case more forcing is required. */
- break;
-
- default:
-
- spin_unlock(&rnp->lock);
- WARN_ON_ONCE(1);
+ spin_lock(&rnp->lock);
break;
}
+ spin_unlock(&rnp->lock);
unlock_fqs_ret:
spin_unlock_irqrestore(&rsp->fqslock, flags);
}
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