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[PATCH] rcu: Skip additional checks if rcu_cpu_stall_suppress is set

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If rcu_kick_kthreads is set, and gp is in progress, check_cpu_stall()
does checks to figure out whether jiffies is past rsp->jiffies_stall,
doing ordered accesses to avoid any false positives for new grace
period initialization after a sufficiently large idle period. This
extra processing can be skipped if rcu_cpu_stall_suppress is set.

Fixes: 8c7c4829a81c ("rcu: Awaken grace-period kthread if too long since FQS")
Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org>
---
 kernel/rcu/tree.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 51d4c3a..91b7552 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1562,10 +1562,13 @@ static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
 	unsigned long js;
 	struct rcu_node *rnp;
 
-	if ((rcu_cpu_stall_suppress && !rcu_kick_kthreads) ||
-	    !rcu_gp_in_progress(rsp))
+	if (!rcu_gp_in_progress(rsp))
 		return;
 	rcu_stall_kick_kthreads(rsp);
+
+	if (rcu_cpu_stall_suppress)
+		return;
+
 	j = jiffies;
 
 	/*
-- 
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a
member of the Code Aurora Forum, hosted by The Linux Foundation

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[PATCH] rcu: Skip additional checks if rcu_cpu_stall_suppress is set Neeraj Upadhyay <neeraju@codeaurora.org> - 2017-08-08 19:30 +0200
  Re: [PATCH] rcu: Skip additional checks if rcu_cpu_stall_suppress is  set "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-08-08 20:10 +0200
    Re: [PATCH] rcu: Skip additional checks if rcu_cpu_stall_suppress is  set Neeraj Upadhyay <neeraju@codeaurora.org> - 2017-08-08 21:00 +0200
      Re: [PATCH] rcu: Skip additional checks if rcu_cpu_stall_suppress is  set "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-08-09 00:00 +0200

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