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authorPaul E. McKenney <paulmck@kernel.org>2020-08-11 10:33:39 -0700
committerPaul E. McKenney <paulmck@kernel.org>2020-08-24 18:45:36 -0700
commitd685514260e21aabd65a9aa8be045766bdaa0549 (patch)
tree376e37434d4e26cd06c879713f1d71e7bd10bb2e /kernel/rcu/rcutorture.c
parent299c7d94f635ab93ffb0468aec6b6e2176ec5cbf (diff)
downloadlinux-next-d685514260e21aabd65a9aa8be045766bdaa0549.tar.gz
rcutorture: Allow pointer leaks to test diagnostic code
This commit adds an rcutorture.leakpointer module parameter that intentionally leaks an RCU-protected pointer out of the RCU read-side critical section and checks to see if the corresponding grace period has elapsed, emitting a WARN_ON_ONCE() if so. This module parameter can be used to test facilities like CONFIG_RCU_STRICT_GRACE_PERIOD that end grace periods quickly. While in the area, also document rcutorture.irqreader, which was previously left out. Reported-by Jann Horn <jannh@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu/rcutorture.c')
-rw-r--r--kernel/rcu/rcutorture.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 983f82fccb18..916ea4f66e4b 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -87,6 +87,7 @@ torture_param(bool, gp_normal, false,
"Use normal (non-expedited) GP wait primitives");
torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
+torture_param(int, leakpointer, 0, "Leak pointer dereferences from readers");
torture_param(int, n_barrier_cbs, 0,
"# of callbacks/kthreads for barrier testing");
torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
@@ -1401,6 +1402,9 @@ static bool rcu_torture_one_read(struct torture_random_state *trsp)
preempt_enable();
rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
WARN_ON_ONCE(readstate & RCUTORTURE_RDR_MASK);
+ // This next splat is expected behavior if leakpointer, especially
+ // for CONFIG_RCU_STRICT_GRACE_PERIOD=y kernels.
+ WARN_ON_ONCE(leakpointer && READ_ONCE(p->rtort_pipe_count) > 1);
/* If error or close call, record the sequence of reader protections. */
if ((pipe_count > 1 || completed > 1) && !xchg(&err_segs_recorded, 1)) {