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Three driver callbacks schedule a reset and wait for its completion: ndo_change_mtu(), ethtool set_ringparam(), and ethtool set_channels(). Waiting for reset in ndo_change_mtu() and set_ringparam() was added by commitc2ed2403f1("iavf: Wait for reset in callbacks which trigger it") to fix a race condition where adding an interface to bonding immediately after MTU or ring parameter change failed because the interface was still in __RESETTING state. The same commit also added waiting in iavf_set_priv_flags(), which was later removed by commit53844673d5("iavf: kill "legacy-rx" for good"). Waiting in set_channels() was introduced earlier by commit4e5e6b5d9d("iavf: Fix return of set the new channel count") to ensure the PF has enough time to complete the VF reset when changing channel count, and to return correct error codes to userspace. Commitef490bbb22("iavf: Add net_shaper_ops support") added net_shaper_ops to iavf, which required reset_task to use _locked NAPI variants (napi_enable_locked, napi_disable_locked) that need the netdev instance lock. Later, commit7e4d784f58("net: hold netdev instance lock during rtnetlink operations") and commit2bcf4772e4("net: ethtool: try to protect all callback with netdev instance lock") started holding the netdev instance lock during ndo and ethtool callbacks for drivers with net_shaper_ops. Finally, commit120f28a6f3("iavf: get rid of the crit lock") replaced the driver's crit_lock with netdev_lock in reset_task, causing incorrect behavior: the callback holds netdev_lock and waits for reset_task, but reset_task needs the same lock: Thread 1 (callback) Thread 2 (reset_task) ------------------- --------------------- netdev_lock() [blocked on workqueue] ndo_change_mtu() or ethtool op iavf_schedule_reset() iavf_wait_for_reset() iavf_reset_task() waiting... netdev_lock() <- blocked This does not strictly deadlock because iavf_wait_for_reset() uses wait_event_interruptible_timeout() with a 5-second timeout. The wait eventually times out, the callback returns an error to userspace, and after the lock is released reset_task completes the reset. This leads to incorrect behavior: userspace sees an error even though the configuration change silently takes effect after the timeout. Fix this by extracting the reset logic from iavf_reset_task() into a new iavf_reset_step() function that expects netdev_lock to be already held. The three callbacks now call iavf_reset_step() directly instead of scheduling the work and waiting, performing the reset synchronously in the caller's context which already holds netdev_lock. This eliminates both the incorrect error reporting and the need for iavf_wait_for_reset(), which is removed along with the now-unused reset_waitqueue. The workqueue-based iavf_reset_task() becomes a thin wrapper that acquires netdev_lock and calls iavf_reset_step(), preserving its use for PF-initiated resets. The callbacks may block for several seconds while iavf_reset_step() polls hardware registers, but this is acceptable since netdev_lock is a per-device mutex and only serializes operations on the same interface. v3: - Remove netif_running() guard from iavf_set_channels(). Unlike set_ringparam where descriptor counts are picked up by iavf_open() directly, num_req_queues is only consumed during iavf_reinit_interrupt_scheme() in the reset path. Skipping the reset on a down device would silently discard the channel count change. - Remove dead reset_waitqueue code (struct field, init, and all wake_up calls) since iavf_wait_for_reset() was the only consumer. Fixes:120f28a6f3("iavf: get rid of the crit lock") Reviewed-by: Jacob Keller <jacob.e.keller@intel.com> Signed-off-by: Petr Oros <poros@redhat.com> Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com> Tested-by: Rafal Romanowski <rafal.romanowski@intel.com> Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
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. 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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. 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