* [PATCH] rcu: Check the validity of the boost_kthread_task pointer
@ 2022-03-24 11:15 Zqiang
2022-03-24 16:00 ` Paul E. McKenney
0 siblings, 1 reply; 3+ messages in thread
From: Zqiang @ 2022-03-24 11:15 UTC (permalink / raw)
To: paulmck, frederic, quic_neeraju; +Cc: rcu, linux-kernel
The boost kthreads may spawn failed, although the probability of
creation failure is very low, in consideration of the robustness
of the code, add boost_kthread_task pointer detection.
Signed-off-by: Zqiang <qiang1.zhang@intel.com>
---
kernel/rcu/tree_plugin.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 6b9bcd45c7b2..fd642f14f31f 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1125,7 +1125,8 @@ static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags)
__releases(rnp->lock)
{
raw_lockdep_assert_held_rcu_node(rnp);
- if (!rcu_preempt_blocked_readers_cgp(rnp) && rnp->exp_tasks == NULL) {
+ if (!rnp->boost_kthread_task ||
+ (!rcu_preempt_blocked_readers_cgp(rnp) && rnp->exp_tasks == NULL)) {
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
return;
}
--
2.25.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] rcu: Check the validity of the boost_kthread_task pointer
2022-03-24 11:15 [PATCH] rcu: Check the validity of the boost_kthread_task pointer Zqiang
@ 2022-03-24 16:00 ` Paul E. McKenney
2022-03-25 0:00 ` Zhang, Qiang1
0 siblings, 1 reply; 3+ messages in thread
From: Paul E. McKenney @ 2022-03-24 16:00 UTC (permalink / raw)
To: Zqiang; +Cc: frederic, quic_neeraju, rcu, linux-kernel
On Thu, Mar 24, 2022 at 07:15:15PM +0800, Zqiang wrote:
> The boost kthreads may spawn failed, although the probability of
> creation failure is very low, in consideration of the robustness
> of the code, add boost_kthread_task pointer detection.
>
> Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Good catch! As you say, rare, but definitely worth fixing.
I could not resist a bit of wordsmithing. Could you please check
to see if I messed something up?
Thanx, Paul
------------------------------------------------------------------------
commit ad3c438e248cbc41fe30a41287621c3dbfcdf51c
Author: Zqiang <qiang1.zhang@intel.com>
Date: Thu Mar 24 19:15:15 2022 +0800
rcu: Check for successful spawn of ->boost_kthread_task
For the spawning of the priority-boost kthreads can fail, improbable
though this might seem. This commit therefore refrains from attemoting
to initiate RCU priority boosting when The ->boost_kthread_task pointer
is NULL.
Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 6b9bcd45c7b2..d58f6d6073bf 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1125,7 +1125,8 @@ static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags)
__releases(rnp->lock)
{
raw_lockdep_assert_held_rcu_node(rnp);
- if (!rcu_preempt_blocked_readers_cgp(rnp) && rnp->exp_tasks == NULL) {
+ if (!rnp->boost_kthread_task ||
+ (!rcu_preempt_blocked_readers_cgp(rnp) && !rnp->exp_tasks)) {
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
return;
}
^ permalink raw reply related [flat|nested] 3+ messages in thread
* RE: [PATCH] rcu: Check the validity of the boost_kthread_task pointer
2022-03-24 16:00 ` Paul E. McKenney
@ 2022-03-25 0:00 ` Zhang, Qiang1
0 siblings, 0 replies; 3+ messages in thread
From: Zhang, Qiang1 @ 2022-03-25 0:00 UTC (permalink / raw)
To: paulmck; +Cc: frederic, quic_neeraju, rcu, linux-kernel
On Thu, Mar 24, 2022 at 07:15:15PM +0800, Zqiang wrote:
> The boost kthreads may spawn failed, although the probability of
> creation failure is very low, in consideration of the robustness of
> the code, add boost_kthread_task pointer detection.
>
> Signed-off-by: Zqiang <qiang1.zhang@intel.com>
>
>Good catch! As you say, rare, but definitely worth fixing.
>
>I could not resist a bit of wordsmithing. Could you please check to see if I messed something up?
Thanks wordsmithing, I think it's ok.
Thanks,
Zqiang
>
> Thanx, Paul
>
>------------------------------------------------------------------------
>
>commit ad3c438e248cbc41fe30a41287621c3dbfcdf51c
>Author: Zqiang <qiang1.zhang@intel.com>
>Date: Thu Mar 24 19:15:15 2022 +0800
>
> rcu: Check for successful spawn of ->boost_kthread_task
>
> For the spawning of the priority-boost kthreads can fail, improbable
> though this might seem. This commit therefore refrains from attemoting
> to initiate RCU priority boosting when The ->boost_kthread_task pointer
> is NULL.
>
> Signed-off-by: Zqiang <qiang1.zhang@intel.com>
> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
>
>diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 6b9bcd45c7b2..d58f6d6073bf 100644
>--- a/kernel/rcu/tree_plugin.h
>+++ b/kernel/rcu/tree_plugin.h
>@@ -1125,7 +1125,8 @@ static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags)
> __releases(rnp->lock)
> {
> raw_lockdep_assert_held_rcu_node(rnp);
>- if (!rcu_preempt_blocked_readers_cgp(rnp) && rnp->exp_tasks == NULL) {
>+ if (!rnp->boost_kthread_task ||
>+ (!rcu_preempt_blocked_readers_cgp(rnp) && !rnp->exp_tasks)) {
> raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
> return;
> }
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-03-24 11:15 [PATCH] rcu: Check the validity of the boost_kthread_task pointer Zqiang
2022-03-24 16:00 ` Paul E. McKenney
2022-03-25 0:00 ` Zhang, Qiang1
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