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| author | Paul E. McKenney <paulmck@kernel.org> | 2020-03-28 18:53:25 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2020-04-27 11:03:50 -0700 |
| commit | 52b1fc3f798d02a3a9d1cf7a84e98a795223410a (patch) | |
| tree | 1b8f8f588009bf7d08e9d7eaef4512138cd3d84b /kernel/rcu | |
| parent | 5f5fa7ea89dc82d34ed458f4d7a8634e8e9eefce (diff) | |
| download | linux-52b1fc3f798d02a3a9d1cf7a84e98a795223410a.tar.bz2 | |
rcutorture: Add test of holding scheduler locks across rcu_read_unlock()
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>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/rcutorture.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index 5453bd557f43..b348cf816d89 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -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(¤t->pi_lock, flags); cur_ops->readunlock(idxold >> RCUTORTURE_RDR_SHIFT); + if (lockit) + raw_spin_unlock_irqrestore(¤t->pi_lock, flags); + } /* Delay if neither beginning nor end and there was a change. */ if ((statesnew || statesold) && *readstate && newstate) |