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rds_tcp_reset_callbacks() resolves a duelling SYN by storing RDS_CONN_RESETTING into cp_state unconditionally. Nothing serializes that store against the shutdown path: rds_tcp_accept_one() checks for RDS_CONN_CONNECTING or RDS_CONN_ERROR under t_conn_path_lock, but neither rds_conn_path_drop(), which forces RDS_CONN_ERROR, nor rds_conn_shutdown(), which moves the path to RDS_CONN_DISCONNECTING under cp_cm_lock, takes that lock. The store can therefore land on top of a shutdown that is already in progress, or that gets queued right after the accept-side check. When it does, the shutdown worker's final DISCONNECTING -> DOWN transition fails and the path goes through rds_conn_path_error() and a second drop/shutdown cycle instead of a clean reconnect, tearing down the socket the accept path has just installed. Before commitad22d24be6("net/rds: No shortcut out of RDS_CONN_ERROR") a path found in RDS_CONN_RESETTING even made rds_conn_shutdown() bail out altogether. Make the transition conditional: move CONNECTING -> RESETTING (or stay in RESETTING from an earlier duel), and drop the path in any other state. The drop has side effects of its own: it replaces the shutdown's RDS_CONN_DISCONNECTING (or RDS_CONN_ERROR) with RDS_CONN_ERROR and queues one more cp_down_w run. The difference is that rds_conn_shutdown() accepts RDS_CONN_ERROR in its final transition to RDS_CONN_DOWN, so the shutdown in flight completes normally instead of through rds_conn_path_error(); the extra down-work pass then finds the path already down and falls through to the reconnect check, or catches a reconnect that has already started and restarts it. The accept path still installs the new socket, rds_connect_path_complete() then fails its RESETTING -> UP transition and drops it: the raced socket ends up torn down as it does today. The comment at that call site, which promised that rds_connect_path_complete() marks the path RDS_CONN_UP, is updated to name this outcome as well. The state can change again between the failed transitions and the drop. That is inherent to rds_conn_path_drop(), which the socket state-change callbacks also call unconditionally, and costs at most one extra drop/reconnect cycle. Based on Oracle UEK commit "net/rds: Don't force state RDS_CONN_RESETTING" by Gerd Rausch. Fixes:9c79440e2c("RDS: TCP: fix race windows in send-path quiescence by rds_tcp_accept_one()") Signed-off-by: Gerd Rausch <gerd.rausch@oracle.com> [achender: port to net-next: use the two-argument rds_conn_path_transition()/rds_conn_path_drop() and rewrite the changelog for the upstream shutdown path] Signed-off-by: Allison Henderson <achender@kernel.org> Link: https://patch.msgid.link/20260828223921.202913-5-achender@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Linux kernel ============ The Linux kernel is the core of any Linux operating system. It manages hardware, system resources, and provides the fundamental services for all other software. Quick Start ----------- * Report a bug: See Documentation/admin-guide/reporting-issues.rst * Get the latest kernel: https://kernel.org * Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst * Join the community: https://lore.kernel.org/ Essential Documentation ----------------------- All users should be familiar with: * Building requirements: Documentation/process/changes.rst * Code of Conduct: Documentation/process/code-of-conduct.rst * License: See COPYING Documentation can be built with make htmldocs or viewed online at: https://www.kernel.org/doc/html/latest/ Who Are You? ============ Find your role below: * New Kernel Developer: Getting started with kernel development * Academic Researcher: Studying kernel internals and architecture * Security Expert: Hardening and vulnerability analysis * Backport/Maintenance Engineer: Maintaining stable kernels * System Administrator: Configuring and troubleshooting * Maintainer: Leading subsystems and reviewing patches * Hardware Vendor: Writing drivers for new hardware * Distribution Maintainer: Packaging kernels for distros * AI Coding Assistant: LLMs and AI-powered development tools For Specific Users ================== New Kernel Developer -------------------- Welcome! Start your kernel development journey here: * Getting Started: Documentation/process/development-process.rst * Your First Patch: Documentation/process/submitting-patches.rst * Coding Style: Documentation/process/coding-style.rst * Build System: Documentation/kbuild/index.rst * Development Tools: Documentation/dev-tools/index.rst * Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst * Core APIs: Documentation/core-api/index.rst Academic Researcher ------------------- Explore the kernel's architecture and internals: * Researcher Guidelines: Documentation/process/researcher-guidelines.rst * Memory Management: Documentation/mm/index.rst * Scheduler: Documentation/scheduler/index.rst * Networking Stack: Documentation/networking/index.rst * Filesystems: Documentation/filesystems/index.rst * RCU (Read-Copy Update): Documentation/RCU/index.rst * Locking Primitives: Documentation/locking/index.rst * Power Management: Documentation/power/index.rst Security Expert --------------- Security documentation and hardening guides: * Security Documentation: Documentation/security/index.rst * LSM Development: Documentation/security/lsm-development.rst * Self Protection: Documentation/security/self-protection.rst * Reporting Vulnerabilities: Documentation/process/security-bugs.rst * CVE Procedures: Documentation/process/cve.rst * Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst * Security Features: Documentation/userspace-api/seccomp_filter.rst Backport/Maintenance Engineer ----------------------------- Maintain and stabilize kernel versions: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * Backporting Guide: Documentation/process/backporting.rst * Applying Patches: Documentation/process/applying-patches.rst * Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git for Maintainers: Documentation/maintainer/configure-git.rst System Administrator -------------------- Configure, tune, and troubleshoot Linux systems: * Admin Guide: Documentation/admin-guide/index.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst * Tracing/Debugging: Documentation/trace/index.rst * Performance Security: Documentation/admin-guide/perf-security.rst * Hardware Monitoring: Documentation/hwmon/index.rst Maintainer ---------- Lead kernel subsystems and manage contributions: * Maintainer Handbook: Documentation/maintainer/index.rst * Pull Requests: Documentation/maintainer/pull-requests.rst * Managing Patches: Documentation/maintainer/modifying-patches.rst * Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst * Development Process: Documentation/process/maintainer-handbooks.rst * Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git Configuration: Documentation/maintainer/configure-git.rst Hardware Vendor --------------- Write drivers and support new hardware: * Driver API Guide: Documentation/driver-api/index.rst * Driver Model: Documentation/driver-api/driver-model/driver.rst * Device Drivers: Documentation/driver-api/infrastructure.rst * Bus Types: Documentation/driver-api/driver-model/bus.rst * Device Tree Bindings: Documentation/devicetree/bindings/ * Power Management: Documentation/driver-api/pm/index.rst * DMA API: Documentation/core-api/dma-api.rst Distribution Maintainer ----------------------- Package and distribute the kernel: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * ABI Documentation: Documentation/ABI/README * Kernel Configuration: Documentation/kbuild/kconfig.rst * Module Signing: Documentation/admin-guide/module-signing.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst AI Coding Assistant ------------------- CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and follow the AI coding assistants documentation before contributing to the Linux kernel: * Documentation/process/coding-assistants.rst This documentation contains essential requirements about licensing, attribution, and the Developer Certificate of Origin that all AI tools must comply with. Communication and Support ========================= * Mailing Lists: https://lore.kernel.org/ * IRC: #kernelnewbies on irc.oftc.net * Bugzilla: https://bugzilla.kernel.org/ * MAINTAINERS file: Lists subsystem maintainers and mailing lists * Email Clients: Documentation/process/email-clients.rst