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When connected to another host and then unplugging cable lockdep triggers following: ====================================================== WARNING: possible circular locking dependency detected 7.1.0-rc2+ #1775 Tainted: G U ------------------------------------------------------ kworker/u16:6/312 is trying to acquire lock: ffff8881179c70a8 ((work_completion)(&ring->work)){+.+.}-{0:0}, at: __flush_work+0x3cf/0xd10 but task is already holding lock: ffff8881a8b810b0 (&net->connection_lock){+.+.}-{4:4}, at: tbnet_tear_down+0x110/0x720 [thunderbolt_net] which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&net->connection_lock){+.+.}-{4:4}: __mutex_lock+0x19a/0x2490 mutex_lock_nested+0x1b/0x30 tbnet_handle_packet+0x74c/0xd70 [thunderbolt_net] tb_xdomain_handle_request+0x37c/0x4b0 [thunderbolt] tb_domain_event_cb+0xc9/0x140 [thunderbolt] tb_ctl_handle_event+0xd6/0x2c0 [thunderbolt] tb_ctl_rx_callback+0x22c/0xa10 [thunderbolt] ring_work+0x715/0xcb0 [thunderbolt] process_one_work+0x902/0x1790 worker_thread+0x5cd/0xfe0 kthread+0x339/0x420 ret_from_fork+0x79a/0x9d0 ret_from_fork_asm+0x1a/0x30 -> #0 ((work_completion)(&ring->work)){+.+.}-{0:0}: __lock_acquire+0x1592/0x2640 lock_acquire+0x1a3/0x300 __flush_work+0x3e9/0xd10 flush_work+0x21/0x30 tb_ring_stop+0x240/0x840 [thunderbolt] tbnet_tear_down+0x2ff/0x720 [thunderbolt_net] tbnet_stop+0x47/0x1a0 [thunderbolt_net] __dev_close_many+0x19e/0x4e0 netif_close_many+0x1e8/0x640 unregister_netdevice_many_notify+0x6d3/0x22d0 unregister_netdevice_queue+0x2b9/0x3a0 unregister_netdev+0x1c/0x70 tbnet_remove+0x52/0xb0 [thunderbolt_net] tb_service_remove+0x8a/0xe0 [thunderbolt] device_remove+0xc5/0x190 device_release_driver_internal+0x3db/0x590 device_release_driver+0x12/0x20 bus_remove_device+0x2c1/0x580 device_del+0x3d9/0x9f0 device_unregister+0x17/0xc0 unregister_service+0x46/0x60 [thunderbolt] device_for_each_child_reverse+0xfa/0x180 tb_xdomain_unregister+0x57/0xe0 [thunderbolt] unregister_unplugged_xdomain+0x101/0x1a0 [thunderbolt] bus_for_each_dev+0x111/0x1a0 tb_domain_unregister_unplugged_xdomains+0x98/0xe0 [thunderbolt] tb_handle_hotplug+0xc3/0x2bb0 [thunderbolt] process_one_work+0x902/0x1790 worker_thread+0x5cd/0xfe0 kthread+0x339/0x420 ret_from_fork+0x79a/0x9d0 ret_from_fork_asm+0x1a/0x30 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&net->connection_lock); lock((work_completion)(&ring->work)); lock(&net->connection_lock); lock((work_completion)(&ring->work)); This in fact is false positive because they involve unrelated rings (and unrelated work structures). In the first one it is ring 0 which is used for control traffic and in the second it is dealing with another ring used for the high-speed traffic. Fix this by using separate lock class for each ring worker. Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> |
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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