* [PATCH AUTOSEL 5.10] rcu: Mark rcu_cpu_kthread() accesses to ->rcu_cpu_has_work
@ 2023-07-02 19:58 Sasha Levin
2023-07-12 10:11 ` Pavel Machek
0 siblings, 1 reply; 3+ messages in thread
From: Sasha Levin @ 2023-07-02 19:58 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Paul E. McKenney, Sasha Levin, frederic, quic_neeraju, joel, josh,
boqun.feng, rcu
From: "Paul E. McKenney" <paulmck@kernel.org>
[ Upstream commit a24c1aab652ebacf9ea62470a166514174c96fe1 ]
The rcu_data structure's ->rcu_cpu_has_work field can be modified by
any CPU attempting to wake up the rcuc kthread. Therefore, this commit
marks accesses to this field from the rcu_cpu_kthread() function.
This data race was reported by KCSAN. Not appropriate for backporting
due to failure being unlikely.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/rcu/tree.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index eec8e2f7537eb..b2c1ab260ed56 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2810,12 +2810,12 @@ static void rcu_cpu_kthread(unsigned int cpu)
*statusp = RCU_KTHREAD_RUNNING;
local_irq_disable();
work = *workp;
- *workp = 0;
+ WRITE_ONCE(*workp, 0);
local_irq_enable();
if (work)
rcu_core();
local_bh_enable();
- if (*workp == 0) {
+ if (!READ_ONCE(*workp)) {
trace_rcu_utilization(TPS("End CPU kthread@rcu_wait"));
*statusp = RCU_KTHREAD_WAITING;
return;
--
2.39.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH AUTOSEL 5.10] rcu: Mark rcu_cpu_kthread() accesses to ->rcu_cpu_has_work
@ 2023-07-09 14:55 Sasha Levin
0 siblings, 0 replies; 3+ messages in thread
From: Sasha Levin @ 2023-07-09 14:55 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Paul E. McKenney, Sasha Levin, frederic, quic_neeraju, joel, josh,
boqun.feng, rcu
From: "Paul E. McKenney" <paulmck@kernel.org>
[ Upstream commit a24c1aab652ebacf9ea62470a166514174c96fe1 ]
The rcu_data structure's ->rcu_cpu_has_work field can be modified by
any CPU attempting to wake up the rcuc kthread. Therefore, this commit
marks accesses to this field from the rcu_cpu_kthread() function.
This data race was reported by KCSAN. Not appropriate for backporting
due to failure being unlikely.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/rcu/tree.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index eec8e2f7537eb..b2c1ab260ed56 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2810,12 +2810,12 @@ static void rcu_cpu_kthread(unsigned int cpu)
*statusp = RCU_KTHREAD_RUNNING;
local_irq_disable();
work = *workp;
- *workp = 0;
+ WRITE_ONCE(*workp, 0);
local_irq_enable();
if (work)
rcu_core();
local_bh_enable();
- if (*workp == 0) {
+ if (!READ_ONCE(*workp)) {
trace_rcu_utilization(TPS("End CPU kthread@rcu_wait"));
*statusp = RCU_KTHREAD_WAITING;
return;
--
2.39.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH AUTOSEL 5.10] rcu: Mark rcu_cpu_kthread() accesses to ->rcu_cpu_has_work
2023-07-02 19:58 Sasha Levin
@ 2023-07-12 10:11 ` Pavel Machek
0 siblings, 0 replies; 3+ messages in thread
From: Pavel Machek @ 2023-07-12 10:11 UTC (permalink / raw)
To: Sasha Levin
Cc: linux-kernel, stable, Paul E. McKenney, frederic, quic_neeraju,
joel, josh, boqun.feng, rcu
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On Sun 2023-07-02 15:58:06, Sasha Levin wrote:
> From: "Paul E. McKenney" <paulmck@kernel.org>
>
> [ Upstream commit a24c1aab652ebacf9ea62470a166514174c96fe1 ]
>
> The rcu_data structure's ->rcu_cpu_has_work field can be modified by
> any CPU attempting to wake up the rcuc kthread. Therefore, this commit
> marks accesses to this field from the rcu_cpu_kthread() function.
>
> This data race was reported by KCSAN. Not appropriate for backporting
> due to failure being unlikely.
Please drop.
Best regards,
Pavel
--
People of Russia, stop Putin before his war on Ukraine escalates.
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