From 0ae9942f03d0d034fdb0a4f44fc99f62a3107987 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 18 Aug 2023 08:53:58 -0700 Subject: [PATCH] rcu: Eliminate rcu_gp_slow_unregister() false positive When using rcutorture as a module, there are a number of conditions that can abort the modprobe operation, for example, when attempting to run both RCU CPU stall warning tests and forward-progress tests. This can cause rcu_torture_cleanup() to be invoked on the unwind path out of rcu_rcu_torture_init(), which will mean that rcu_gp_slow_unregister() is invoked without a matching rcu_gp_slow_register(). This will cause a splat because rcu_gp_slow_unregister() is passed rcu_fwd_cb_nodelay, which does not match a NULL pointer. This commit therefore forgives a mismatch involving a NULL pointer, thus avoiding this false-positive splat. Signed-off-by: Paul E. McKenney Signed-off-by: Frederic Weisbecker --- kernel/rcu/tree.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index aae515071ffd..a83ecab77917 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1260,7 +1260,7 @@ EXPORT_SYMBOL_GPL(rcu_gp_slow_register); /* Unregister a counter, with NULL for not caring which. */ void rcu_gp_slow_unregister(atomic_t *rgssp) { - WARN_ON_ONCE(rgssp && rgssp != rcu_gp_slow_suppress); + WARN_ON_ONCE(rgssp && rgssp != rcu_gp_slow_suppress && rcu_gp_slow_suppress != NULL); WRITE_ONCE(rcu_gp_slow_suppress, NULL); }