* [PATCH] rcu: don't use __this_cpu_* from preemptible context
@ 2014-12-28 16:49 Sasha Levin
2014-12-31 1:59 ` Paul E. McKenney
0 siblings, 1 reply; 2+ messages in thread
From: Sasha Levin @ 2014-12-28 16:49 UTC (permalink / raw)
To: linux-kernel
Cc: Sasha Levin, Paul E. McKenney, Josh Triplett, Steven Rostedt,
Mathieu Desnoyers, Lai Jiangshan
Commit "rcu: Make cond_resched_rcu_qs() apply to normal RCU flavors" has added
debug code which tries to read from __this_cpu in a preemptible code, which
doesn't work too well.
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
---
kernel/rcu/tree_trace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/rcu/tree_trace.c b/kernel/rcu/tree_trace.c
index a9b79ca..fbb6240 100644
--- a/kernel/rcu/tree_trace.c
+++ b/kernel/rcu/tree_trace.c
@@ -122,7 +122,7 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
cpu_is_offline(rdp->cpu) ? '!' : ' ',
ulong2long(rdp->completed), ulong2long(rdp->gpnum),
rdp->passed_quiesce,
- rdp->rcu_qs_ctr_snap == __this_cpu_read(rcu_qs_ctr),
+ rdp->rcu_qs_ctr_snap == per_cpu(rcu_qs_ctr, rdp->cpu),
rdp->qs_pending);
seq_printf(m, " dt=%d/%llx/%d df=%lu",
atomic_read(&rdp->dynticks->dynticks),
--
1.7.10.4
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] rcu: don't use __this_cpu_* from preemptible context
2014-12-28 16:49 [PATCH] rcu: don't use __this_cpu_* from preemptible context Sasha Levin
@ 2014-12-31 1:59 ` Paul E. McKenney
0 siblings, 0 replies; 2+ messages in thread
From: Paul E. McKenney @ 2014-12-31 1:59 UTC (permalink / raw)
To: Sasha Levin
Cc: linux-kernel, Josh Triplett, Steven Rostedt, Mathieu Desnoyers,
Lai Jiangshan
On Sun, Dec 28, 2014 at 11:49:40AM -0500, Sasha Levin wrote:
> Commit "rcu: Make cond_resched_rcu_qs() apply to normal RCU flavors" has added
> debug code which tries to read from __this_cpu in a preemptible code, which
> doesn't work too well.
>
> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Good catch, queued for 3.20 (same as the offending commit).
Thanx, Paul
> ---
> kernel/rcu/tree_trace.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/rcu/tree_trace.c b/kernel/rcu/tree_trace.c
> index a9b79ca..fbb6240 100644
> --- a/kernel/rcu/tree_trace.c
> +++ b/kernel/rcu/tree_trace.c
> @@ -122,7 +122,7 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
> cpu_is_offline(rdp->cpu) ? '!' : ' ',
> ulong2long(rdp->completed), ulong2long(rdp->gpnum),
> rdp->passed_quiesce,
> - rdp->rcu_qs_ctr_snap == __this_cpu_read(rcu_qs_ctr),
> + rdp->rcu_qs_ctr_snap == per_cpu(rcu_qs_ctr, rdp->cpu),
> rdp->qs_pending);
> seq_printf(m, " dt=%d/%llx/%d df=%lu",
> atomic_read(&rdp->dynticks->dynticks),
> --
> 1.7.10.4
>
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2014-12-31 12:35 UTC | newest]
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2014-12-28 16:49 [PATCH] rcu: don't use __this_cpu_* from preemptible context Sasha Levin
2014-12-31 1:59 ` Paul E. McKenney
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