10.12.2021 22:33, Dmitry Osipenko пишет:
Not really, they only prevent the race from occurring while
notifier_has_unique_priority() is running.
If anyone depends on this check for correctness, they need to lock the
rwsem, do the check, do the thing depending on the check while holding
the rwsem and then release the rwsem. Otherwise it is racy.
It's fine that it's a bit "racy" since in the context of this series. We
always do the check after adding new entry, so it's not a problem.
There are two options:
1. Use blocking_notifier_has_unique_priority() like it's done in this
patchset. Remove it after all drivers are converted to the new API and
add blocking_notifier_chain_register_unique().
2. Add blocking_notifier_chain_register_unique(), but don't let it fail
the registration of non-unique entries until all drivers are converted
to the new API.
There is third, perhaps the best option:
3. Add blocking_notifier_chain_register_unique() and fall back to
blocking_notifier_chain_register() if unique fails, do it until all
drivers are converted to the new API.
