Commit 4569c5ee authored Aug 05, 2020 by Paul E. McKenney

rcu/nocb: Add a warning for non-GP kthread running GP code

This commit increases RCU's ability to defend itself by emitting a warning
if one of the nocb CB kthreads invokes the GP kthread's wait function.
This warning augments a similar check that is carried out at the end
of rcutorture testing and when RCU CPU stall warnings are emitted.
The problem with those checks is that the miscreants have long since
departed and disposed of any and all evidence.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

parent c0f97f20

kernel/rcu/tree_plugin.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -1926,6 +1926,7 @@ static void nocb_gp_wait(struct rcu_data *my_rdp)
		* nearest grace period (if any) to wait for next. The CB kthreads
		* and the global grace-period kthread are awakened if needed.
		*/
		WARN_ON_ONCE(my_rdp->nocb_gp_rdp != my_rdp);
		for (rdp = my_rdp; rdp; rdp = rdp->nocb_next_cb_rdp) {
		trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("Check"));
		rcu_nocb_lock_irqsave(rdp, flags);

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