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rcu: Print human-readable message for schedule() in RCU reader

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The WARN_ON_ONCE() invocation within the CONFIG_PREEMPT=y version of
rcu_note_context_switch() triggers when there is a voluntary context
switch in an RCU read-side critical section, but there is quite a gap
between the output of that WARN_ON_ONCE() and this RCU-usage error.
This commit therefore converts the WARN_ON_ONCE() to a WARN_ONCE()
that explicitly describes the problem in its message.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Paul E. McKenney 2021-07-19 11:52:12 -07:00
parent 508958259b
commit 521c89b3a4
1 changed files with 1 additions and 1 deletions
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2
kernel/rcu/tree_plugin.h
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@ -346,7 +346,7 @@ void rcu_note_context_switch(bool preempt)
trace_rcu_utilization(TPS("Start context switch"));
lockdep_assert_irqs_disabled();
WARN_ON_ONCE(!preempt && rcu_preempt_depth() > 0);
WARN_ONCE(!preempt && rcu_preempt_depth() > 0, "Voluntary context switch within RCU read-side critical section!");
if (rcu_preempt_depth() > 0 &&
!t->rcu_read_unlock_special.b.blocked) {