aleph/lkl_linux
1
0
Fork 0
mirror of https://github.com/lkl/linux.git synced 2025-12-19 16:13:19 +09:00
Code Issues Packages Projects Releases Wiki Activity

dma-buf: add dma_resv_for_each_fence_unlocked v8

Browse Source 
Abstract the complexity of iterating over all the fences
in a dma_resv object.

The new loop handles the whole RCU and retry dance and
returns only fences where we can be sure we grabbed the
right one.

v2: fix accessing the shared fences while they might be freed,
    improve kerneldoc, rename _cursor to _iter, add
    dma_resv_iter_is_exclusive, add dma_resv_iter_begin/end

v3: restructor the code, move rcu_read_lock()/unlock() into the
    iterator, add dma_resv_iter_is_restarted()

v4: fix NULL deref when no explicit fence exists, drop superflous
    rcu_read_lock()/unlock() calls.

v5: fix typos in the documentation

v6: fix coding error when excl fence is NULL

v7: one more logic fix

v8: fix index check in dma_resv_iter_is_exclusive()

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> (v7)
Link: https://patchwork.freedesktop.org/patch/msgid/20211005113742.1101-2-christian.koenig@amd.com
This commit is contained in:
Christian König
2021-06-15 15:10:03 +02:00
parent e7bd95a7ed
commit c921ff373b
2 changed files with 195 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

95
include/linux/dma-resv.h
View File

@@ -149,6 +149,101 @@ struct dma_resv {
struct dma_resv_list __rcu *fence;
};
/**
* struct dma_resv_iter - current position into the dma_resv fences
*
* Don't touch this directly in the driver, use the accessor function instead.
*/
struct dma_resv_iter {
/** @obj: The dma_resv object we iterate over */
struct dma_resv *obj;
/** @all_fences: If all fences should be returned */
bool all_fences;
/** @fence: the currently handled fence */
struct dma_fence *fence;
/** @seq: sequence number to check for modifications */
unsigned int seq;
/** @index: index into the shared fences */
unsigned int index;
/** @fences: the shared fences */
struct dma_resv_list *fences;
/** @is_restarted: true if this is the first returned fence */
bool is_restarted;
};
struct dma_fence *dma_resv_iter_first_unlocked(struct dma_resv_iter *cursor);
struct dma_fence *dma_resv_iter_next_unlocked(struct dma_resv_iter *cursor);
/**
* dma_resv_iter_begin - initialize a dma_resv_iter object
* @cursor: The dma_resv_iter object to initialize
* @obj: The dma_resv object which we want to iterate over
* @all_fences: If all fences should be returned or just the exclusive one
*/
static inline void dma_resv_iter_begin(struct dma_resv_iter *cursor,
struct dma_resv *obj,
bool all_fences)
{
cursor->obj = obj;
cursor->all_fences = all_fences;
cursor->fence = NULL;
}
/**
* dma_resv_iter_end - cleanup a dma_resv_iter object
* @cursor: the dma_resv_iter object which should be cleaned up
*
* Make sure that the reference to the fence in the cursor is properly
* dropped.
*/
static inline void dma_resv_iter_end(struct dma_resv_iter *cursor)
{
dma_fence_put(cursor->fence);
}
/**
* dma_resv_iter_is_exclusive - test if the current fence is the exclusive one
* @cursor: the cursor of the current position
*
* Returns true if the currently returned fence is the exclusive one.
*/
static inline bool dma_resv_iter_is_exclusive(struct dma_resv_iter *cursor)
{
return cursor->index == 0;
}
/**
* dma_resv_iter_is_restarted - test if this is the first fence after a restart
* @cursor: the cursor with the current position
*
* Return true if this is the first fence in an iteration after a restart.
*/
static inline bool dma_resv_iter_is_restarted(struct dma_resv_iter *cursor)
{
return cursor->is_restarted;
}
/**
* dma_resv_for_each_fence_unlocked - unlocked fence iterator
* @cursor: a struct dma_resv_iter pointer
* @fence: the current fence
*
* Iterate over the fences in a struct dma_resv object without holding the
* &dma_resv.lock and using RCU instead. The cursor needs to be initialized
* with dma_resv_iter_begin() and cleaned up with dma_resv_iter_end(). Inside
* the iterator a reference to the dma_fence is held and the RCU lock dropped.
* When the dma_resv is modified the iteration starts over again.
*/
#define dma_resv_for_each_fence_unlocked(cursor, fence) \
for (fence = dma_resv_iter_first_unlocked(cursor); \
fence; fence = dma_resv_iter_next_unlocked(cursor))
#define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base)
#define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)