rls: Avoid missed config update from reentrancy #12546
Open
+29
−12
Conversation
This file contains hidden or 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
ejona86
added
the
TODO:backport
ejona86
force-pushed
the
rls-missed-update
branch
from
fb81bf3 to
eae4cae
Compare
Since ChildPolicyWrapper() called into the child before childPolicyMap.put(), it is possible for that child to call back into RLS and further update state without that child being known. When CDS is_dynamic=true (since ca99a8c), it registers the cluster with XdsDependencyManager, which adds a watch to XdsClient. If XdsClient already has the results cached then the watch callback can be enqueued immediately onto the syncContext and execute still within the constructor. Calling into the child with the lock held isn't great, as it allows for this type of reentrancy bug. But that'll take larger changes to fix. b/464116731
ejona86
force-pushed
the
rls-missed-update
branch
from
eae4cae to
7bf431e
Compare
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
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Outdated suggestions cannot be applied.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 ChildPolicyWrapper() called into the child before childPolicyMap.put(), it is possible for that child to call back into RLS and further update state without that child being known. When CDS is_dynamic=true (since ca99a8c), it registers the cluster with XdsDependencyManager, which adds a watch to XdsClient. If XdsClient already has the results cached then the watch callback can be enqueued immediately onto the syncContext and execute still within the constructor.
Calling into the child with the lock held isn't great, as it allows for this type of reentrancy bug. But that'll take larger changes to fix.
b/464116731