rculist: add list_splice_rcu() for private lists

This patch adds a helper function, list_splice_rcu(), to safely splice
a private (non-RCU-protected) list into an RCU-protected list.

The function ensures that only the pointer visible to RCU readers
(prev->next) is updated using rcu_assign_pointer(), while the rest of
the list manipulations are performed with regular assignments, as the
source list is private and not visible to concurrent RCU readers.

This is useful for moving elements from a private list into a global
RCU-protected list, ensuring safe publication for RCU readers.
Subsystems with some sort of batching mechanism from userspace can
benefit from this new function.

The function __list_splice_rcu() has been added for clarity and to
follow the same pattern as in the existing list_splice*() interfaces,
where there is a check to ensure that the list to splice is not
empty. Note that __list_splice_rcu() has no documentation for this
reason.

Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

0 files changed, 0 insertions, 0 deletions