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SubjectRe: [PATCH 04/13] module: use RCU to synchronize find_module
On Fri, Jan 29, 2021 at 04:29:02PM +0100, Miroslav Benes wrote:
> >
> > - mutex_lock(&module_mutex);
> > + rcu_read_lock_sched();
> > /*
> > * We do not want to block removal of patched modules and therefore
> > * we do not take a reference here. The patches are removed by
> > @@ -74,7 +75,7 @@ static void klp_find_object_module(struct klp_object *obj)
> > if (mod && mod->klp_alive)
>
> RCU always baffles me a bit, so I'll ask. Don't we need
> rcu_dereference_sched() here? "mod" comes from a RCU-protected list, so I
> wonder.

rcu_dereference* is only used for dereferencing points where that
reference itself is RCU protected, that is the lookup of mod itself down
in find_module_all in this case.

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