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SubjectRe: [PATCH tip/core/rcu 11/15] rcu: Avoid spurious RCU CPU stall warnings
On Thu, Aug 30, 2012 at 11:56:24AM -0700, Paul E. McKenney wrote:
> From: "Paul E. McKenney" <paul.mckenney@linaro.org>
>
> If a given CPU avoids the idle loop but also avoids starting a new
> RCU grace period for a full minute, RCU can issue spurious RCU CPU
> stall warnings. This commit fixes this issue by adding a check for
> ongoing grace period to avoid these spurious stall warnings.
>
> Reported-by: Becky Bruce <bgillbruce@gmail.com>
> Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

Reviewed-by: Josh Triplett <josh@joshtriplett.org>

> ---
> kernel/rcutree.c | 3 ++-
> 1 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/kernel/rcutree.c b/kernel/rcutree.c
> index fbe43b0..e58097b 100644
> --- a/kernel/rcutree.c
> +++ b/kernel/rcutree.c
> @@ -820,7 +820,8 @@ static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
> j = ACCESS_ONCE(jiffies);
> js = ACCESS_ONCE(rsp->jiffies_stall);
> rnp = rdp->mynode;
> - if ((ACCESS_ONCE(rnp->qsmask) & rdp->grpmask) && ULONG_CMP_GE(j, js)) {
> + if (rcu_gp_in_progress(rsp) &&
> + (ACCESS_ONCE(rnp->qsmask) & rdp->grpmask) && ULONG_CMP_GE(j, js)) {
>
> /* We haven't checked in, so go dump stack. */
> print_cpu_stall(rsp);
> --
> 1.7.8
>


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