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rcu: Eliminate rcu_gp_slow_unregister() false positive 

[ Upstream commit 0ae9942f03d0d034fdb0a4f44fc99f62a3107987 ]

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 <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Paul E. McKenney 2023-08-18 08:53:58 -07:00 committed by Greg Kroah-Hartman
parent e160de344f
commit 81ba4dd37a
1 changed files with 1 additions and 1 deletions
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2
kernel/rcu/tree.c
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@ -1298,7 +1298,7 @@ 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);
}