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[RFC,tip/core/rcu,11/13] rcu: Identify dyntick-idle CPUs on first force_quiescent_state() pass

Message ID 1322523185-456-11-git-send-email-paulmck@linux.vnet.ibm.com
State Accepted
Commit f0e7c19db8798b4b991a2c71911e71f5dfdb348f
Headers show

Commit Message

Paul E. McKenney Nov. 28, 2011, 11:33 p.m. UTC 
From: Paul E. McKenney <paul.mckenney@linaro.org>

Fixes and workarounds for a number of issues (for example, that in
df4012edc) make it safe to once again detect dyntick-idle CPUs on the
first pass of force_quiescent_state(), so this commit makes that change.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 kernel/rcutree.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
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Patch

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index aab9ed5..69bb372 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -607,7 +607,7 @@  int rcu_is_cpu_rrupt_from_idle(void)
 static int dyntick_save_progress_counter(struct rcu_data *rdp)
 {
 	rdp->dynticks_snap = atomic_add_return(0, &rdp->dynticks->dynticks);
-	return 0;
+	return (rdp->dynticks_snap & 0x1) == 0;
 }
 
 /*