Commit 0ae9942f authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Frederic Weisbecker
Browse files

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: default avatarPaul E. McKenney <paulmck@kernel.org>
Signed-off-by: default avatarFrederic Weisbecker <frederic@kernel.org>
parent 2cbc482d

kernel/rcu/tree.c

+1 −1
Original line number Diff line number Diff line
@@ -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);

}