rcutorture: Add test of holding scheduler locks across rcu_read_unlock() (52b1fc3f) · Commits · 戴 / test

Now that it should be safe to hold scheduler locks across rcu_read_unlock(), even in cases where the corresponding RCU read-side critical section might have been preempted and boosted, the commit adds a test of this capability to rcutorture. This has been tested on current mainline (which can deadlock in this situation), and lockdep duly reported the expected deadlock. On -rcu, lockdep is silent, thus far, anyway. Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by:

Paul E. McKenney <paulmck@kernel.org>

kernel/rcu/rcutorture.c

+9 −1

Original line number	Diff line number	Diff line
		@@ -1147,6 +1147,7 @@ static void rcutorture_one_extend(int *readstate, int newstate,
		struct torture_random_state *trsp,
		struct rt_read_seg *rtrsp)
		{
		unsigned long flags;
		int idxnew = -1;
		int idxold = *readstate;
		int statesnew = ~*readstate & newstate;
		@@ -1181,8 +1182,15 @@ static void rcutorture_one_extend(int *readstate, int newstate,
		rcu_read_unlock_bh();
		if (statesold & RCUTORTURE_RDR_SCHED)
		rcu_read_unlock_sched();
		if (statesold & RCUTORTURE_RDR_RCU)
		if (statesold & RCUTORTURE_RDR_RCU) {
		bool lockit = !statesnew && !(torture_random(trsp) & 0xffff);

		if (lockit)
		raw_spin_lock_irqsave(&current->pi_lock, flags);
		cur_ops->readunlock(idxold >> RCUTORTURE_RDR_SHIFT);
		if (lockit)
		raw_spin_unlock_irqrestore(&current->pi_lock, flags);
		}

		/* Delay if neither beginning nor end and there was a change. */
		if ((statesnew \|\| statesold) && *readstate && newstate)

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