* [PATCH] rcu/exp: Fix check for idle context in rcu_exp_handler
@ 2021-12-13 6:10 Neeraj Upadhyay
2021-12-13 11:34 ` Frederic Weisbecker
0 siblings, 1 reply; 3+ messages in thread
From: Neeraj Upadhyay @ 2021-12-13 6:10 UTC (permalink / raw)
To: paulmck, josh, rostedt, mathieu.desnoyers, jiangshanlai, joel
Cc: rcu, linux-kernel, urezki, frederic, boqun.feng, Neeraj Upadhyay
For PREEMPT_RCU, the rcu_exp_handler() function checks
whether the current CPU is in idle, by calling
rcu_dynticks_curr_cpu_in_eqs(). However, rcu_exp_handler()
is called in IPI handler context. So, it should be checking
the idle context using rcu_is_cpu_rrupt_from_idle(). Fix this
by using rcu_is_cpu_rrupt_from_idle() instead of
rcu_dynticks_curr_cpu_in_eqs(). Non-preempt configuration
already uses the correct check.
Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
---
kernel/rcu/tree_exp.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index 237a79989aba..1568c8ef185b 100644
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -656,7 +656,7 @@ static void rcu_exp_handler(void *unused)
*/
if (!depth) {
if (!(preempt_count() & (PREEMPT_MASK | SOFTIRQ_MASK)) ||
- rcu_dynticks_curr_cpu_in_eqs()) {
+ rcu_is_cpu_rrupt_from_idle()) {
rcu_report_exp_rdp(rdp);
} else {
WRITE_ONCE(rdp->cpu_no_qs.b.exp, true);
--
2.17.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] rcu/exp: Fix check for idle context in rcu_exp_handler
2021-12-13 6:10 [PATCH] rcu/exp: Fix check for idle context in rcu_exp_handler Neeraj Upadhyay
@ 2021-12-13 11:34 ` Frederic Weisbecker
2021-12-13 19:20 ` Paul E. McKenney
0 siblings, 1 reply; 3+ messages in thread
From: Frederic Weisbecker @ 2021-12-13 11:34 UTC (permalink / raw)
To: Neeraj Upadhyay
Cc: paulmck, josh, rostedt, mathieu.desnoyers, jiangshanlai, joel,
rcu, linux-kernel, urezki, boqun.feng
On Mon, Dec 13, 2021 at 11:40:24AM +0530, Neeraj Upadhyay wrote:
> For PREEMPT_RCU, the rcu_exp_handler() function checks
> whether the current CPU is in idle, by calling
> rcu_dynticks_curr_cpu_in_eqs(). However, rcu_exp_handler()
> is called in IPI handler context. So, it should be checking
> the idle context using rcu_is_cpu_rrupt_from_idle(). Fix this
> by using rcu_is_cpu_rrupt_from_idle() instead of
> rcu_dynticks_curr_cpu_in_eqs(). Non-preempt configuration
> already uses the correct check.
>
> Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
> ---
> kernel/rcu/tree_exp.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
> index 237a79989aba..1568c8ef185b 100644
> --- a/kernel/rcu/tree_exp.h
> +++ b/kernel/rcu/tree_exp.h
> @@ -656,7 +656,7 @@ static void rcu_exp_handler(void *unused)
> */
> if (!depth) {
> if (!(preempt_count() & (PREEMPT_MASK | SOFTIRQ_MASK)) ||
> - rcu_dynticks_curr_cpu_in_eqs()) {
> + rcu_is_cpu_rrupt_from_idle()) {
> rcu_report_exp_rdp(rdp);
> } else {
> WRITE_ONCE(rdp->cpu_no_qs.b.exp, true);
> --
> 2.17.1
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] rcu/exp: Fix check for idle context in rcu_exp_handler
2021-12-13 11:34 ` Frederic Weisbecker
@ 2021-12-13 19:20 ` Paul E. McKenney
0 siblings, 0 replies; 3+ messages in thread
From: Paul E. McKenney @ 2021-12-13 19:20 UTC (permalink / raw)
To: Frederic Weisbecker
Cc: Neeraj Upadhyay, josh, rostedt, mathieu.desnoyers, jiangshanlai,
joel, rcu, linux-kernel, urezki, boqun.feng
On Mon, Dec 13, 2021 at 12:34:55PM +0100, Frederic Weisbecker wrote:
> On Mon, Dec 13, 2021 at 11:40:24AM +0530, Neeraj Upadhyay wrote:
> > For PREEMPT_RCU, the rcu_exp_handler() function checks
> > whether the current CPU is in idle, by calling
> > rcu_dynticks_curr_cpu_in_eqs(). However, rcu_exp_handler()
> > is called in IPI handler context. So, it should be checking
> > the idle context using rcu_is_cpu_rrupt_from_idle(). Fix this
> > by using rcu_is_cpu_rrupt_from_idle() instead of
> > rcu_dynticks_curr_cpu_in_eqs(). Non-preempt configuration
> > already uses the correct check.
> >
> > Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
>
> Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Queued for further review and testing, thank you both!
Thanx, Paul
> > ---
> > kernel/rcu/tree_exp.h | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
> > index 237a79989aba..1568c8ef185b 100644
> > --- a/kernel/rcu/tree_exp.h
> > +++ b/kernel/rcu/tree_exp.h
> > @@ -656,7 +656,7 @@ static void rcu_exp_handler(void *unused)
> > */
> > if (!depth) {
> > if (!(preempt_count() & (PREEMPT_MASK | SOFTIRQ_MASK)) ||
> > - rcu_dynticks_curr_cpu_in_eqs()) {
> > + rcu_is_cpu_rrupt_from_idle()) {
> > rcu_report_exp_rdp(rdp);
> > } else {
> > WRITE_ONCE(rdp->cpu_no_qs.b.exp, true);
> > --
> > 2.17.1
> >
^ permalink raw reply [flat|nested] 3+ messages in thread
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2021-12-13 6:10 [PATCH] rcu/exp: Fix check for idle context in rcu_exp_handler Neeraj Upadhyay
2021-12-13 11:34 ` Frederic Weisbecker
2021-12-13 19:20 ` Paul E. McKenney
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