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If our exported dma-bufs are imported by another instance of our driver, that instance will typically have the imported dma-bufs locked during dma_buf_map_attachment(). But the exporter also locks the same reservation object in the map_dma_buf() callback, which leads to recursive locking. So taking the lock inside _pin_pages_unlocked() is incorrect. Additionally, the current pinning code path is contrary to the defined way that pinning should occur. Remove the explicit pin/unpin from the map/umap functions and move them to the attach/detach allowing correct locking to occur, and to match the static dma-buf drm_prime pattern. Add a live selftest to exercise both dynamic and non-dynamic exports. v2: - Extend the selftest with a fake dynamic importer. - Provide real pin and unpin callbacks to not abuse the interface. v3: (ruhl) - Remove the dynamic export support and move the pinning into the attach/detach path. v4: (ruhl) - Put pages does not need to assert on the dma-resv v5: (jason) - Lock around dma_buf_unmap_attachment() when emulating a dynamic importer in the subtests. - Use pin_pages_unlocked v6: (jason) - Use dma_buf_attach instead of dma_buf_attach_dynamic in the selftests v7: (mauld) - Use __i915_gem_object_get_pages (2 __underscores) instead of the 4 ____underscore version in the selftests v8: (mauld) - Drop the kernel doc from the static i915_gem_dmabuf_attach function - Add missing "err = PTR_ERR()" to a bunch of selftest error cases Reported-by: Michael J. Ruhl <michael.j.ruhl@intel.com> Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com> Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com> Signed-off-by: Jason Ekstrand <jason@jlekstrand.net> Reviewed-by: Jason Ekstrand <jason@jlekstrand.net> Signed-off-by: Matthew Auld <matthew.auld@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20210723172142.3273510-8-jason@jlekstrand.net
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 Restructured Text 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.