sync: fix Notify to clone the waker before locking its waiter list #4129
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rustfmt ci seems a bit upset? |
hawkw
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Sep 22, 2021
Since a waker can trigger arbitrary code, such as with a custom waker, and even more so now that it can emit a tracing event that could do respond, we must be careful about the internal state when that code is triggered. The clone method of a waker is one of those instances. This changes the internals of `Notify` so that the waker is cloned *before* locking the waiter list. While this does mean that in some contended cases, we'll have made an optimistic clone, it makes `Notify` more robust and correct. Note that the included test case is built from an instance that did happen naturally in another project, see tokio-rs/console#133.
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Oh yea, |
Darksonn
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Sep 23, 2021
suikammd
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…okio-rs#4129) Since a waker can trigger arbitrary code, such as with a custom waker, and even more so now that it can emit a tracing event that could do respond, we must be careful about the internal state when that code is triggered. The clone method of a waker is one of those instances. This changes the internals of `Notify` so that the waker is cloned *before* locking the waiter list. While this does mean that in some contended cases, we'll have made an optimistic clone, it makes `Notify` more robust and correct. Note that the included test case is built from an instance that did happen naturally in another project, see tokio-rs/console#133.
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Since a waker can trigger arbitrary code, such as with a custom waker,
and even more so now that it can emit a tracing event that could do
respond, we must be careful about the internal state when that code is
triggered. The clone method of a waker is one of those instances.
This changes the internals of
Notifyso that the waker is clonedbefore locking the waiter list. While this does mean that in some
contended cases, we'll have made an optimistic clone, it makes
Notifymore robust and correct.
Note that the included test case is built from an instance that did
happen naturally in another project, see
tokio-rs/console#133.