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rcu-tasks: RCU Tasks Trace grace-period kthread has implicit QS

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Because the task driving the grace-period kthread is in quiescent state
throughout, this commit excludes it from the list of tasks from which
a quiescent state is needed.

This does mean that attaching a sleepable BPF program to function in
kernel/rcu/tasks.h is a bad idea, by the way.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: KP Singh <kpsingh@kernel.org>
This commit is contained in:
Paul E. McKenney 2022-05-24 18:19:17 -07:00
parent 897ba84dc5
commit 5d4c90d755
1 changed files with 3 additions and 2 deletions
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5
kernel/rcu/tasks.h
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@ -1433,8 +1433,9 @@ static void rcu_tasks_trace_pertask(struct task_struct *t,
struct list_head *hop)
{
// During early boot when there is only the one boot CPU, there
// is no idle task for the other CPUs. Just return.
if (unlikely(t == NULL))
// is no idle task for the other CPUs. Also, the grace-period
// kthread is always in a quiescent state. Either way, just return.
if (unlikely(t == NULL) || t == current)
return;
rcu_st_need_qs(t, 0);