dma_resv Struct Reference

#include <dma-resv.h>

Public Attributes
struct ww_mutex	lock
struct dma_resv_list __rcu *	fences

Detailed Description

struct dma_resv - a reservation object manages fences for a buffer

This is a container for dma_fence objects which needs to handle multiple use cases.

One use is to synchronize cross-driver access to a struct dma_buf, either for dynamic buffer management or just to handle implicit synchronization between different users of the buffer in userspace. See &dma_buf.resv for a more in-depth discussion.

The other major use is to manage access and locking within a driver in a buffer based memory manager. struct ttm_buffer_object is the canonical example here, since this is where reservation objects originated from. But use in drivers is spreading and some drivers also manage struct drm_gem_object with the same scheme.

Member Data Documentation

fences

struct dma_resv_list __rcu* dma_resv::fences

@fences:

Array of fences which where added to the dma_resv object

A new fence is added by calling dma_resv_add_fence(). Since this often needs to be done past the point of no return in command submission it cannot fail, and therefore sufficient slots need to be reserved by calling dma_resv_reserve_fences().

lock

struct ww_mutex dma_resv::lock

@lock:

Update side lock. Don't use directly, instead use the wrapper functions like dma_resv_lock() and dma_resv_unlock().

Drivers which use the reservation object to manage memory dynamically also use this lock to protect buffer object state like placement, allocation policies or throughout command submission.

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The documentation for this struct was generated from the following file:

• XenevaOS/BaseHdr/linux/dma-resv.h