Commit 67c97fb7 authored by Christian König's avatar Christian König
Browse files

dma-buf: add reservation_object_fences helper 



Add a new helper to get a consistent set of pointers from the reservation
object. While at it group all access helpers together in the header file.

v2: correctly return shared_count as well

Signed-off-by: default avatarChristian König <christian.koenig@amd.com>
Reviewed-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/322378/?series=64837&rev=1
parent 0e2f733a

drivers/dma-buf/dma-buf.c

+5 −26
Original line number Diff line number Diff line
@@ -199,7 +199,7 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll) 
	struct reservation_object_list *fobj;

	struct dma_fence *fence_excl;

	__poll_t events;

	unsigned shared_count, seq;

	unsigned shared_count;



	dmabuf = file->private_data;

	if (!dmabuf || !dmabuf->resv)
@@ -213,21 +213,8 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll) 
	if (!events)

		return 0;



retry:

	seq = read_seqcount_begin(&resv->seq);

	rcu_read_lock();



	fobj = rcu_dereference(resv->fence);

	if (fobj)

		shared_count = fobj->shared_count;

	else

		shared_count = 0;

	fence_excl = rcu_dereference(resv->fence_excl);

	if (read_seqcount_retry(&resv->seq, seq)) {

		rcu_read_unlock();

		goto retry;

	}



	reservation_object_fences(resv, &fence_excl, &fobj, &shared_count);

	if (fence_excl && (!(events & EPOLLOUT) || shared_count == 0)) {

		struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_excl;

		__poll_t pevents = EPOLLIN;
@@ -1157,7 +1144,6 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused) 
	struct reservation_object *robj;

	struct reservation_object_list *fobj;

	struct dma_fence *fence;

	unsigned seq;

	int count = 0, attach_count, shared_count, i;

	size_t size = 0;
@@ -1188,16 +1174,9 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused) 
				buf_obj->name ?: "");



		robj = buf_obj->resv;

		while (true) {

			seq = read_seqcount_begin(&robj->seq);

		rcu_read_lock();

			fobj = rcu_dereference(robj->fence);

			shared_count = fobj ? fobj->shared_count : 0;

			fence = rcu_dereference(robj->fence_excl);

			if (!read_seqcount_retry(&robj->seq, seq))

				break;

		reservation_object_fences(robj, &fence, &fobj, &shared_count);

		rcu_read_unlock();

		}



		if (fence)

			seq_printf(s, "\tExclusive fence: %s %s %ssignalled\n",

drivers/dma-buf/reservation.c

+26 −56
Original line number Diff line number Diff line
@@ -317,17 +317,15 @@ int reservation_object_copy_fences(struct reservation_object *dst, 
{

	struct reservation_object_list *src_list, *dst_list;

	struct dma_fence *old, *new;

	unsigned i;

	unsigned int i, shared_count;



	reservation_object_assert_held(dst);



	rcu_read_lock();

	src_list = rcu_dereference(src->fence);



retry:

	if (src_list) {

		unsigned shared_count = src_list->shared_count;



	reservation_object_fences(src, &new, &src_list, &shared_count);

	if (shared_count) {

		rcu_read_unlock();



		dst_list = reservation_object_list_alloc(shared_count);
@@ -335,14 +333,14 @@ retry: 
			return -ENOMEM;



		rcu_read_lock();

		src_list = rcu_dereference(src->fence);

		if (!src_list || src_list->shared_count > shared_count) {

		reservation_object_fences(src, &new, &src_list, &shared_count);

		if (!src_list || shared_count > dst_list->shared_max) {

			kfree(dst_list);

			goto retry;

		}



		dst_list->shared_count = 0;

		for (i = 0; i < src_list->shared_count; ++i) {

		for (i = 0; i < shared_count; ++i) {

			struct dma_fence *fence;



			fence = rcu_dereference(src_list->shared[i]);
@@ -352,7 +350,6 @@ retry: 


			if (!dma_fence_get_rcu(fence)) {

				reservation_object_list_free(dst_list);

				src_list = rcu_dereference(src->fence);

				goto retry;

			}
@@ -367,7 +364,10 @@ retry: 
		dst_list = NULL;

	}



	new = dma_fence_get_rcu_safe(&src->fence_excl);

	if (new && !dma_fence_get_rcu(new)) {

		reservation_object_list_free(dst_list);

		goto retry;

	}

	rcu_read_unlock();



	src_list = reservation_object_get_list(dst);
@@ -413,19 +413,18 @@ int reservation_object_get_fences_rcu(struct reservation_object *obj, 


	do {

		struct reservation_object_list *fobj;

		unsigned int i, seq;

		unsigned int i;

		size_t sz = 0;



		shared_count = i = 0;

		i = 0;



		rcu_read_lock();

		seq = read_seqcount_begin(&obj->seq);

		reservation_object_fences(obj, &fence_excl, &fobj,

					  &shared_count);



		fence_excl = rcu_dereference(obj->fence_excl);

		if (fence_excl && !dma_fence_get_rcu(fence_excl))

			goto unlock;



		fobj = rcu_dereference(obj->fence);

		if (fobj)

			sz += sizeof(*shared) * fobj->shared_max;
@@ -453,7 +452,6 @@ int reservation_object_get_fences_rcu(struct reservation_object *obj, 
				break;

			}

			shared = nshared;

			shared_count = fobj ? fobj->shared_count : 0;

			for (i = 0; i < shared_count; ++i) {

				shared[i] = rcu_dereference(fobj->shared[i]);

				if (!dma_fence_get_rcu(shared[i]))
@@ -461,7 +459,7 @@ int reservation_object_get_fences_rcu(struct reservation_object *obj, 
			}

		}



		if (i != shared_count || read_seqcount_retry(&obj->seq, seq)) {

		if (i != shared_count) {

			while (i--)

				dma_fence_put(shared[i]);

			dma_fence_put(fence_excl);
@@ -505,18 +503,17 @@ long reservation_object_wait_timeout_rcu(struct reservation_object *obj, 
					 bool wait_all, bool intr,

					 unsigned long timeout)

{

	struct reservation_object_list *fobj;

	struct dma_fence *fence;

	unsigned seq, shared_count;

	unsigned shared_count;

	long ret = timeout ? timeout : 1;

	int i;



retry:

	shared_count = 0;

	seq = read_seqcount_begin(&obj->seq);

	rcu_read_lock();

	i = -1;



	fence = rcu_dereference(obj->fence_excl);

	reservation_object_fences(obj, &fence, &fobj, &shared_count);

	if (fence && !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {

		if (!dma_fence_get_rcu(fence))

			goto unlock_retry;
@@ -531,12 +528,6 @@ retry: 
	}



	if (wait_all) {

		struct reservation_object_list *fobj =

						rcu_dereference(obj->fence);



		if (fobj)

			shared_count = fobj->shared_count;



		for (i = 0; !fence && i < shared_count; ++i) {

			struct dma_fence *lfence = rcu_dereference(fobj->shared[i]);
@@ -559,11 +550,6 @@ retry: 


	rcu_read_unlock();

	if (fence) {

		if (read_seqcount_retry(&obj->seq, seq)) {

			dma_fence_put(fence);

			goto retry;

		}



		ret = dma_fence_wait_timeout(fence, intr, ret);

		dma_fence_put(fence);

		if (ret > 0 && wait_all && (i + 1 < shared_count))
@@ -608,24 +594,19 @@ reservation_object_test_signaled_single(struct dma_fence *passed_fence) 
bool reservation_object_test_signaled_rcu(struct reservation_object *obj,

					  bool test_all)

{

	unsigned seq, shared_count;

	struct reservation_object_list *fobj;

	struct dma_fence *fence_excl;

	unsigned shared_count;

	int ret;



	rcu_read_lock();

retry:

	ret = true;

	shared_count = 0;

	seq = read_seqcount_begin(&obj->seq);



	reservation_object_fences(obj, &fence_excl, &fobj, &shared_count);

	if (test_all) {

		unsigned i;



		struct reservation_object_list *fobj =

						rcu_dereference(obj->fence);



		if (fobj)

			shared_count = fobj->shared_count;



		for (i = 0; i < shared_count; ++i) {

			struct dma_fence *fence = rcu_dereference(fobj->shared[i]);
@@ -635,23 +616,12 @@ retry: 
			else if (!ret)

				break;

		}



		if (read_seqcount_retry(&obj->seq, seq))

			goto retry;

	}



	if (!shared_count) {

		struct dma_fence *fence_excl = rcu_dereference(obj->fence_excl);



		if (fence_excl) {

			ret = reservation_object_test_signaled_single(

								fence_excl);

	if (!shared_count && fence_excl) {

		ret = reservation_object_test_signaled_single(fence_excl);

		if (ret < 0)

			goto retry;



			if (read_seqcount_retry(&obj->seq, seq))

				goto retry;

		}

	}



	rcu_read_unlock();

include/linux/reservation.h

+70 −45
Original line number Diff line number Diff line
@@ -81,6 +81,25 @@ struct reservation_object { 
#define reservation_object_assert_held(obj) \

	lockdep_assert_held(&(obj)->lock.base)



/**

 * reservation_object_get_excl - get the reservation object's

 * exclusive fence, with update-side lock held

 * @obj: the reservation object

 *

 * Returns the exclusive fence (if any).  Does NOT take a

 * reference. Writers must hold obj->lock, readers may only

 * hold a RCU read side lock.

 *

 * RETURNS

 * The exclusive fence or NULL

 */

static inline struct dma_fence *

reservation_object_get_excl(struct reservation_object *obj)

{

	return rcu_dereference_protected(obj->fence_excl,

					 reservation_object_held(obj));

}



/**

 * reservation_object_get_list - get the reservation object's

 * shared fence list, with update-side lock held
@@ -96,6 +115,57 @@ reservation_object_get_list(struct reservation_object *obj) 
					 reservation_object_held(obj));

}



/**

 * reservation_object_fences - read consistent fence pointers

 * @obj: reservation object where we get the fences from

 * @excl: pointer for the exclusive fence

 * @list: pointer for the shared fence list

 *

 * Make sure we have a consisten exclusive fence and shared fence list.

 * Must be called with rcu read side lock held.

 */

static inline void

reservation_object_fences(struct reservation_object *obj,

			  struct dma_fence **excl,

			  struct reservation_object_list **list,

			  u32 *shared_count)

{

	unsigned int seq;



	do {

		seq = read_seqcount_begin(&obj->seq);

		*excl = rcu_dereference(obj->fence_excl);

		*list = rcu_dereference(obj->fence);

		*shared_count = *list ? (*list)->shared_count : 0;

	} while (read_seqcount_retry(&obj->seq, seq));

}



/**

 * reservation_object_get_excl_rcu - get the reservation object's

 * exclusive fence, without lock held.

 * @obj: the reservation object

 *

 * If there is an exclusive fence, this atomically increments it's

 * reference count and returns it.

 *

 * RETURNS

 * The exclusive fence or NULL if none

 */

static inline struct dma_fence *

reservation_object_get_excl_rcu(struct reservation_object *obj)

{

	struct dma_fence *fence;



	if (!rcu_access_pointer(obj->fence_excl))

		return NULL;



	rcu_read_lock();

	fence = dma_fence_get_rcu_safe(&obj->fence_excl);

	rcu_read_unlock();



	return fence;

}



/**

 * reservation_object_lock - lock the reservation object

 * @obj: the reservation object
@@ -239,51 +309,6 @@ reservation_object_unlock(struct reservation_object *obj) 
	ww_mutex_unlock(&obj->lock);

}



/**

 * reservation_object_get_excl - get the reservation object's

 * exclusive fence, with update-side lock held

 * @obj: the reservation object

 *

 * Returns the exclusive fence (if any).  Does NOT take a

 * reference. Writers must hold obj->lock, readers may only

 * hold a RCU read side lock.

 *

 * RETURNS

 * The exclusive fence or NULL

 */

static inline struct dma_fence *

reservation_object_get_excl(struct reservation_object *obj)

{

	return rcu_dereference_protected(obj->fence_excl,

					 reservation_object_held(obj));

}



/**

 * reservation_object_get_excl_rcu - get the reservation object's

 * exclusive fence, without lock held.

 * @obj: the reservation object

 *

 * If there is an exclusive fence, this atomically increments it's

 * reference count and returns it.

 *

 * RETURNS

 * The exclusive fence or NULL if none

 */

static inline struct dma_fence *

reservation_object_get_excl_rcu(struct reservation_object *obj)

{

	struct dma_fence *fence;



	if (!rcu_access_pointer(obj->fence_excl))

		return NULL;



	rcu_read_lock();

	fence = dma_fence_get_rcu_safe(&obj->fence_excl);

	rcu_read_unlock();



	return fence;

}



void reservation_object_init(struct reservation_object *obj);

void reservation_object_fini(struct reservation_object *obj);

int reservation_object_reserve_shared(struct reservation_object *obj,