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Jesse.Zhang
648a0dc0d7
This resolves a deadlock between user queue management and GPU reset
paths by enforcing consistent lock ordering.
The deadlock occurred when:
1. Process exit path (amdgpu_userq_mgr_fini) would:
- Take uqm->userq_mutex
- Then try to take adev->userq_mutex for list operations
2. GPU reset path (amdgpu_userq_pre_reset) would:
- Take adev->userq_mutex first (for list traversal)
- Then take uqm->userq_mutex
The solution establishes a strict top-down locking order:
1. Always take adev->userq_mutex before any uqm->userq_mutex
2. Maintain this order consistently across all code paths
Changes made:
- Reordered locking in amdgpu_userq_mgr_fini() to take device lock first
- Kept existing proper order in amdgpu_userq_pre_reset()
- Simplified the fini flow by removing redundant operations
This prevents circular dependencies while maintaining thread safety
during both normal operation and GPU reset scenarios.
Fixes: 4ce60dbada ("drm/amdgpu: store userq_managers in a list in adev")
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Arvind Yadav <Arvind.Yadav@amd.com>
Signed-off-by: Jesse Zhang <Jesse.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.