sync: fix Notify to clone the waker before locking its waiter list #4129
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
|
rustfmt ci seems a bit upset? |
hawkw
approved these changes
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.
seanmonstar
force-pushed
the
sean/notify-waker-clone-before-lock
branch
from
a97d55b to
d91a448
Compare
|
Oh yea, |
Darksonn
approved these changes
Sep 23, 2021
suikammd
pushed a commit
to suikammd/tokio
that referenced
this pull request
Oct 7, 2021
…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.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
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.