319c933c71
The export dma-buf cache is semantically similar to an flink name. So semantically it makes sense to treat it the same and remove the name (i.e. the dma_buf pointer) and its references when the last gem handle disappears. Again we need to be careful, but double so: Not just could someone race and export with a gem close ioctl (so we need to recheck obj->handle_count again when assigning the new name), but multiple exports can also race against each another. This is prevented by holding the dev->object_name_lock across the entire section which touches obj->dma_buf. With the new scheme we also need to reinstate the obj->dma_buf link at import time (in case the only reference userspace has held in-between was through the dma-buf fd and not through any native gem handle). For simplicity we don't check whether it's a native object but unconditionally set up that link - with the new scheme of removing the obj->dma_buf reference when the last handle disappears we can do that. To make it clear that this is not just for exported buffers anymore als rename it from export_dma_buf to dma_buf. To make sure that now one can race a fd_to_handle or handle_to_fd with gem_close we use the same tricks as in flink of extending the dev->object_name_locking critical section. With this change we finally have a guaranteed 1:1 relationship (at least for native objects) between gem objects and dma-bufs, even accounting for races (which can happen since the dma-buf itself holds a reference while in-flight). This prevent igt/prime_self_import/export-vs-gem_close-race from Oopsing the kernel. There is still a leak though since the per-file priv dma-buf/handle cache handling is racy. That will be fixed in a later patch. v2: Remove the bogus dma_buf_put from the export_and_register_object failure path if we've raced with the handle count dropping to 0. Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Dave Airlie <airlied@redhat.com> |
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.. | ||
i2c | ||
ttm | ||
drm_agpsupport.h | ||
drm_buffer.h | ||
drm_cache.h | ||
drm_core.h | ||
drm_crtc.h | ||
drm_crtc_helper.h | ||
drm_dp_helper.h | ||
drm_edid.h | ||
drm_encoder_slave.h | ||
drm_fb_cma_helper.h | ||
drm_fb_helper.h | ||
drm_fixed.h | ||
drm_flip_work.h | ||
drm_gem_cma_helper.h | ||
drm_global.h | ||
drm_hashtab.h | ||
drm_mem_util.h | ||
drm_memory.h | ||
drm_mm.h | ||
drm_os_linux.h | ||
drm_pciids.h | ||
drm_rect.h | ||
drm_sysfs.h | ||
drm_usb.h | ||
drm_vma_manager.h | ||
drmP.h | ||
exynos_drm.h | ||
gma_drm.h | ||
i915_drm.h | ||
i915_powerwell.h | ||
intel-gtt.h |