Reject stale CQ callbacks after socket revival - #3412
Open
legionxiong wants to merge 1 commit into
Open
Conversation
A CQ callback can remain queued across Reset() and run after the main socket has been revived with a different CQ. Verify that the callback's CQ SocketId still matches the endpoint before accessing RDMA resources. Add a regression test covering a stale callback from an older generation. Signed-off-by: Lijin Xiong <legion.xiong@gmail.com>
legionxiong
force-pushed
the
fix-rdma-stale-cq-callback
branch
from
July 27, 2026 05:29
831b4fc to
010a3e1
Compare
legionxiong
changed the title
Contributor
There was a problem hiding this comment.
Pull request overview
This PR hardens RDMA completion-queue (CQ) polling against “stale” queued callbacks that can survive an endpoint Reset/Revive cycle and inadvertently operate on a new CQ/resource generation. It does so by validating that the CQ socket invoking RdmaEndpoint::PollCq is still the endpoint’s current CQ socket, and adds a regression test to prevent reintroducing the crash class described in #3410.
Changes:
- Add a guard in
RdmaEndpoint::PollCqto immediately return when the callback’s CQ socket ID does not match the endpoint’s current_cq_sid. - Add a unit test that exercises
PollCqwith a “stale” CQ socket to ensure it does not touch the new/current generation.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| test/brpc_rdma_unittest.cpp | Adds a regression test for stale CQ callbacks not polling a new generation. |
| src/brpc/rdma/rdma_endpoint.cpp | Rejects PollCq execution when invoked by a non-current CQ socket (m->id() != ep->_cq_sid). |
💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.
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
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.
What problem does this PR solve?
Issue Number: resolves #3410
Problem Summary:
An RDMA completion-queue callback may remain queued after its endpoint is
reset. If the main socket is later revived with a new CQ, the stale callback
can successfully acquire the revived socket and continue operating on the
endpoint's new generation.
This may cause the stale callback to access invalid or mismatched RDMA
resources in
RdmaEndpoint::PollCq, potentially resulting in a crash.What is changed and the side effects?
Changed:
RdmaEndpoint::PollCqstill matches theendpoint's current
_cq_sid.has switched to a new CQ.
Side effects:
Performance effects: One
SocketIdcomparison is added to eachPollCqinvocation. The overhead is negligible.
Breaking backward compatibility: No.