On Mon, Mar 21, 2022 at 2:59 PM Christian König
<ckoenig.leichtzumerken@xxxxxxxxx> wrote:
>
> Instead of distingting between shared and exclusive fences specify
> the fence usage while adding fences.
>
> Rework all drivers to use this interface instead and deprecate the old one.
>
> v2: some kerneldoc comments suggested by Daniel
> v3: fix a missing case in radeon
> v4: rebase on nouveau changes, fix lockdep and temporary disable warning
> v5: more documentation updates
>
> Signed-off-by: Christian König <christian.koenig@xxxxxxx>
> ---
> drivers/dma-buf/dma-resv.c | 345 ++++++++----------
> drivers/dma-buf/st-dma-resv.c | 101 ++---
> .../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 2 +-
> drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 6 +-
> drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 6 +-
> drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c | 10 +-
> drivers/gpu/drm/i915/gem/i915_gem_busy.c | 13 +-
> drivers/gpu/drm/i915/gem/i915_gem_clflush.c | 3 +-
> drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c | 5 +-
> drivers/gpu/drm/i915/i915_vma.c | 6 +-
> drivers/gpu/drm/lima/lima_gem.c | 2 +-
> drivers/gpu/drm/msm/msm_gem_submit.c | 2 +-
> drivers/gpu/drm/nouveau/nouveau_bo.c | 9 +-
> drivers/gpu/drm/nouveau/nouveau_fence.c | 4 +-
> drivers/gpu/drm/qxl/qxl_release.c | 3 +-
> drivers/gpu/drm/radeon/radeon_object.c | 6 +-
> drivers/gpu/drm/ttm/ttm_bo.c | 2 +-
> drivers/gpu/drm/ttm/ttm_bo_util.c | 5 +-
> drivers/gpu/drm/ttm/ttm_execbuf_util.c | 6 +-
> drivers/gpu/drm/v3d/v3d_gem.c | 4 +-
> drivers/gpu/drm/vc4/vc4_gem.c | 2 +-
> drivers/gpu/drm/vgem/vgem_fence.c | 9 +-
> drivers/gpu/drm/virtio/virtgpu_gem.c | 3 +-
> drivers/gpu/drm/vmwgfx/vmwgfx_bo.c | 3 +-
> include/linux/dma-buf.h | 17 +-
> include/linux/dma-resv.h | 72 ++--
> 26 files changed, 276 insertions(+), 370 deletions(-)
>
> diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
> index bb7b023c2d33..26257ba1527e 100644
> --- a/drivers/dma-buf/dma-resv.c
> +++ b/drivers/dma-buf/dma-resv.c
> @@ -44,12 +44,12 @@
> /**
> * DOC: Reservation Object Overview
> *
> - * The reservation object provides a mechanism to manage shared and
> - * exclusive fences associated with a buffer. A reservation object
> - * can have attached one exclusive fence (normally associated with
> - * write operations) or N shared fences (read operations). The RCU
> - * mechanism is used to protect read access to fences from locked
> - * write-side updates.
> + * The reservation object provides a mechanism to manage a container of
> + * dma_fence object associated with a resource. A reservation object
> + * can have any number of fences attaches to it. Each fence carring an usage
> + * parameter determining how the operation represented by the fence is using the
> + * resource. The RCU mechanism is used to protect read access to fences from
> + * locked write-side updates.
> *
> * See struct dma_resv for more details.
> */
> @@ -57,29 +57,74 @@
> DEFINE_WD_CLASS(reservation_ww_class);
> EXPORT_SYMBOL(reservation_ww_class);
>
> +/* Mask for the lower fence pointer bits */
> +#define DMA_RESV_LIST_MASK 0x3
> +
> struct dma_resv_list {
> struct rcu_head rcu;
> - u32 shared_count, shared_max;
> - struct dma_fence __rcu *shared[];
> + u32 num_fences, max_fences;
> + struct dma_fence __rcu *table[];
> };
>
> +/**
> + * dma_resv_list_entry - extract fence and usage from a list entry
> + * @list: the list to extract and entry from
> + * @index: which entry we want
> + * @resv: optional dma_resv obj for lockdep check that the access is allowed
> + * @fence: the resulting fence
> + * @usage: the resulting usage
> + *
> + * Extract the fence and usage flags from an RCU protected entry in the list.
> + */
> +static void dma_resv_list_entry(struct dma_resv_list *list, unsigned int index,
> + struct dma_resv *resv, struct dma_fence **fence,
> + enum dma_resv_usage *usage)
> +{
> + long tmp;
> +
> + tmp = (long)rcu_dereference_check(list->table[index],
> + resv ? dma_resv_held(resv) : true);
> + *fence = (struct dma_fence *)(tmp & ~DMA_RESV_LIST_MASK);
> + if (usage)
> + *usage = tmp & DMA_RESV_LIST_MASK;
> +}
> +
> +/**
> + * dma_resv_list_set - set fence and usage at a specific index
> + * @list: the list to modify
> + * @index: where to make the change
> + * @fence: the fence to set
> + * @usage: the usage to set
> + *
> + * Set the fence and usage flags at the specific index in the list.
> + */
> +static void dma_resv_list_set(struct dma_resv_list *list,
> + unsigned int index,
> + struct dma_fence *fence,
> + enum dma_resv_usage usage)
> +{
> + long tmp = ((long)fence) | usage;
> +
> + RCU_INIT_POINTER(list->table[index], (struct dma_fence *)tmp);
> +}
> +
> /**
> * dma_resv_list_alloc - allocate fence list
> - * @shared_max: number of fences we need space for
> + * @max_fences: number of fences we need space for
> *
> * Allocate a new dma_resv_list and make sure to correctly initialize
> - * shared_max.
> + * max_fences.
> */
> -static struct dma_resv_list *dma_resv_list_alloc(unsigned int shared_max)
> +static struct dma_resv_list *dma_resv_list_alloc(unsigned int max_fences)
> {
> struct dma_resv_list *list;
>
> - list = kmalloc(struct_size(list, shared, shared_max), GFP_KERNEL);
> + list = kmalloc(struct_size(list, table, max_fences), GFP_KERNEL);
> if (!list)
> return NULL;
>
> - list->shared_max = (ksize(list) - offsetof(typeof(*list), shared)) /
> - sizeof(*list->shared);
> + list->max_fences = (ksize(list) - offsetof(typeof(*list), table)) /
> + sizeof(*list->table);
>
> return list;
> }
> @@ -97,9 +142,12 @@ static void dma_resv_list_free(struct dma_resv_list *list)
> if (!list)
> return;
>
> - for (i = 0; i < list->shared_count; ++i)
> - dma_fence_put(rcu_dereference_protected(list->shared[i], true));
> + for (i = 0; i < list->num_fences; ++i) {
> + struct dma_fence *fence;
>
> + dma_resv_list_entry(list, i, NULL, &fence, NULL);
> + dma_fence_put(fence);
> + }
> kfree_rcu(list, rcu);
> }
>
> @@ -112,8 +160,7 @@ void dma_resv_init(struct dma_resv *obj)
> ww_mutex_init(&obj->lock, &reservation_ww_class);
> seqcount_ww_mutex_init(&obj->seq, &obj->lock);
>
> - RCU_INIT_POINTER(obj->fence, NULL);
> - RCU_INIT_POINTER(obj->fence_excl, NULL);
> + RCU_INIT_POINTER(obj->fences, NULL);
> }
> EXPORT_SYMBOL(dma_resv_init);
>
> @@ -123,46 +170,31 @@ EXPORT_SYMBOL(dma_resv_init);
> */
> void dma_resv_fini(struct dma_resv *obj)
> {
> - struct dma_resv_list *fobj;
> - struct dma_fence *excl;
> -
> /*
> * This object should be dead and all references must have
> * been released to it, so no need to be protected with rcu.
> */
> - excl = rcu_dereference_protected(obj->fence_excl, 1);
> - if (excl)
> - dma_fence_put(excl);
> -
> - fobj = rcu_dereference_protected(obj->fence, 1);
> - dma_resv_list_free(fobj);
> + dma_resv_list_free(rcu_dereference_protected(obj->fences, true));
> ww_mutex_destroy(&obj->lock);
> }
> EXPORT_SYMBOL(dma_resv_fini);
>
> -static inline struct dma_fence *
> -dma_resv_excl_fence(struct dma_resv *obj)
> +static inline struct dma_resv_list *dma_resv_fences_list(struct dma_resv *obj)
> {
> - return rcu_dereference_check(obj->fence_excl, dma_resv_held(obj));
> -}
> -
> -static inline struct dma_resv_list *dma_resv_shared_list(struct dma_resv *obj)
> -{
> - return rcu_dereference_check(obj->fence, dma_resv_held(obj));
> + return rcu_dereference_check(obj->fences, dma_resv_held(obj));
> }
>
> /**
> - * dma_resv_reserve_fences - Reserve space to add shared fences to
> - * a dma_resv.
> + * dma_resv_reserve_fences - Reserve space to add fences to a dma_resv object.
> * @obj: reservation object
> * @num_fences: number of fences we want to add
> *
> - * Should be called before dma_resv_add_shared_fence(). Must
> - * be called with @obj locked through dma_resv_lock().
> + * Should be called before dma_resv_add_fence(). Must be called with @obj
> + * locked through dma_resv_lock().
> *
> * Note that the preallocated slots need to be re-reserved if @obj is unlocked
> - * at any time before calling dma_resv_add_shared_fence(). This is validated
> - * when CONFIG_DEBUG_MUTEXES is enabled.
> + * at any time before calling dma_resv_add_fence(). This is validated when
> + * CONFIG_DEBUG_MUTEXES is enabled.
> *
> * RETURNS
> * Zero for success, or -errno
> @@ -174,11 +206,11 @@ int dma_resv_reserve_fences(struct dma_resv *obj, unsigned int num_fences)
>
> dma_resv_assert_held(obj);
>
> - old = dma_resv_shared_list(obj);
> - if (old && old->shared_max) {
> - if ((old->shared_count + num_fences) <= old->shared_max)
> + old = dma_resv_fences_list(obj);
> + if (old && old->max_fences) {
> + if ((old->num_fences + num_fences) <= old->max_fences)
> return 0;
> - max = max(old->shared_count + num_fences, old->shared_max * 2);
> + max = max(old->num_fences + num_fences, old->max_fences * 2);
> } else {
> max = max(4ul, roundup_pow_of_two(num_fences));
> }
> @@ -193,27 +225,27 @@ int dma_resv_reserve_fences(struct dma_resv *obj, unsigned int num_fences)
> * references from the old struct are carried over to
> * the new.
> */
> - for (i = 0, j = 0, k = max; i < (old ? old->shared_count : 0); ++i) {
> + for (i = 0, j = 0, k = max; i < (old ? old->num_fences : 0); ++i) {
> + enum dma_resv_usage usage;
> struct dma_fence *fence;
>
> - fence = rcu_dereference_protected(old->shared[i],
> - dma_resv_held(obj));
> + dma_resv_list_entry(old, i, obj, &fence, &usage);
> if (dma_fence_is_signaled(fence))
> - RCU_INIT_POINTER(new->shared[--k], fence);
> + RCU_INIT_POINTER(new->table[--k], fence);
> else
> - RCU_INIT_POINTER(new->shared[j++], fence);
> + dma_resv_list_set(new, j++, fence, usage);
> }
> - new->shared_count = j;
> + new->num_fences = j;
>
> /*
> * We are not changing the effective set of fences here so can
> * merely update the pointer to the new array; both existing
> * readers and new readers will see exactly the same set of
> - * active (unsignaled) shared fences. Individual fences and the
> + * active (unsignaled) fences. Individual fences and the
> * old array are protected by RCU and so will not vanish under
> * the gaze of the rcu_read_lock() readers.
> */
> - rcu_assign_pointer(obj->fence, new);
> + rcu_assign_pointer(obj->fences, new);
>
> if (!old)
> return 0;
> @@ -222,7 +254,7 @@ int dma_resv_reserve_fences(struct dma_resv *obj, unsigned int num_fences)
> for (i = k; i < max; ++i) {
> struct dma_fence *fence;
>
> - fence = rcu_dereference_protected(new->shared[i],
> + fence = rcu_dereference_protected(new->table[i],
> dma_resv_held(obj));
> dma_fence_put(fence);
> }
> @@ -234,37 +266,39 @@ EXPORT_SYMBOL(dma_resv_reserve_fences);
>
> #ifdef CONFIG_DEBUG_MUTEXES
> /**
> - * dma_resv_reset_shared_max - reset shared fences for debugging
> + * dma_resv_reset_max_fences - reset fences for debugging
> * @obj: the dma_resv object to reset
> *
> - * Reset the number of pre-reserved shared slots to test that drivers do
> + * Reset the number of pre-reserved fence slots to test that drivers do
> * correct slot allocation using dma_resv_reserve_fences(). See also
> - * &dma_resv_list.shared_max.
> + * &dma_resv_list.max_fences.
> */
> -void dma_resv_reset_shared_max(struct dma_resv *obj)
> +void dma_resv_reset_max_fences(struct dma_resv *obj)
> {
> - struct dma_resv_list *fences = dma_resv_shared_list(obj);
> + struct dma_resv_list *fences = dma_resv_fences_list(obj);
>
> dma_resv_assert_held(obj);
>
> - /* Test shared fence slot reservation */
> + /* Test fence slot reservation */
> if (fences)
> - fences->shared_max = fences->shared_count;
> + fences->max_fences = fences->num_fences;
> }
> -EXPORT_SYMBOL(dma_resv_reset_shared_max);
> +EXPORT_SYMBOL(dma_resv_reset_max_fences);
> #endif
>
> /**
> - * dma_resv_add_shared_fence - Add a fence to a shared slot
> + * dma_resv_add_fence - Add a fence to the dma_resv obj
> * @obj: the reservation object
> - * @fence: the shared fence to add
> + * @fence: the fence to add
> + * @usage: how the fence is used, see enum dma_resv_usage
> *
> - * Add a fence to a shared slot, @obj must be locked with dma_resv_lock(), and
> + * Add a fence to a slot, @obj must be locked with dma_resv_lock(), and
> * dma_resv_reserve_fences() has been called.
> *
> * See also &dma_resv.fence for a discussion of the semantics.
> */
> -void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence)
> +void dma_resv_add_fence(struct dma_resv *obj, struct dma_fence *fence,
> + enum dma_resv_usage usage)
> {
> struct dma_resv_list *fobj;
> struct dma_fence *old;
> @@ -274,44 +308,45 @@ void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence)
>
> dma_resv_assert_held(obj);
>
> - /* Drivers should not add containers here, instead add each fence
> - * individually.
> + /* TODO: Drivers should not add containers here, instead add each fence
> + * individually. Disabled for now until we cleaned up amdgpu/ttm.
> */
> - WARN_ON(dma_fence_is_container(fence));
> + /* WARN_ON(dma_fence_is_container(fence)); */
>
> - fobj = dma_resv_shared_list(obj);
> - count = fobj->shared_count;
> + fobj = dma_resv_fences_list(obj);
> + count = fobj->num_fences;
>
> write_seqcount_begin(&obj->seq);
>
> for (i = 0; i < count; ++i) {
> + enum dma_resv_usage old_usage;
>
> - old = rcu_dereference_protected(fobj->shared[i],
> - dma_resv_held(obj));
> - if (old->context == fence->context ||
> + dma_resv_list_entry(fobj, i, obj, &old, &old_usage);
> + if ((old->context == fence->context && old_usage >= usage) ||
> dma_fence_is_signaled(old))
> goto replace;
> }
>
> - BUG_ON(fobj->shared_count >= fobj->shared_max);
> + BUG_ON(fobj->num_fences >= fobj->max_fences);
> old = NULL;
> count++;
>
> replace:
> - RCU_INIT_POINTER(fobj->shared[i], fence);
> - /* pointer update must be visible before we extend the shared_count */
> - smp_store_mb(fobj->shared_count, count);
> + dma_resv_list_set(fobj, i, fence, usage);
> + /* pointer update must be visible before we extend the num_fences */
> + smp_store_mb(fobj->num_fences, count);
>
> write_seqcount_end(&obj->seq);
> dma_fence_put(old);
> }
> -EXPORT_SYMBOL(dma_resv_add_shared_fence);
> +EXPORT_SYMBOL(dma_resv_add_fence);
>
> /**
> * dma_resv_replace_fences - replace fences in the dma_resv obj
> * @obj: the reservation object
> * @context: the context of the fences to replace
> * @replacement: the new fence to use instead
> + * @usage: how the new fence is used, see enum dma_resv_usage
> *
> * Replace fences with a specified context with a new fence. Only valid if the
> * operation represented by the original fence has no longer access to the
> @@ -321,107 +356,72 @@ EXPORT_SYMBOL(dma_resv_add_shared_fence);
> * update fence which makes the resource inaccessible.
> */
> void dma_resv_replace_fences(struct dma_resv *obj, uint64_t context,
> - struct dma_fence *replacement)
> + struct dma_fence *replacement,
> + enum dma_resv_usage usage)
> {
> struct dma_resv_list *list;
> - struct dma_fence *old;
> unsigned int i;
>
> dma_resv_assert_held(obj);
>
> + list = dma_resv_fences_list(obj);
> write_seqcount_begin(&obj->seq);
> + for (i = 0; list && i < list->num_fences; ++i) {
> + struct dma_fence *old;
>
> - old = dma_resv_excl_fence(obj);
> - if (old->context == context) {
> - RCU_INIT_POINTER(obj->fence_excl, dma_fence_get(replacement));
> - dma_fence_put(old);
> - }
> -
> - list = dma_resv_shared_list(obj);
> - for (i = 0; list && i < list->shared_count; ++i) {
> - old = rcu_dereference_protected(list->shared[i],
> - dma_resv_held(obj));
> + dma_resv_list_entry(list, i, obj, &old, NULL);
> if (old->context != context)
> continue;
>
> - rcu_assign_pointer(list->shared[i], dma_fence_get(replacement));
> + dma_resv_list_set(list, i, replacement, usage);
> dma_fence_put(old);
> }
> -
> write_seqcount_end(&obj->seq);
> }
> EXPORT_SYMBOL(dma_resv_replace_fences);
>
> /**
> - * dma_resv_add_excl_fence - Add an exclusive fence.
> - * @obj: the reservation object
> - * @fence: the exclusive fence to add
> + * dma_resv_iter_restart_unlocked - restart the unlocked iterator
> + * @cursor: The dma_resv_iter object to restart
> *
> - * Add a fence to the exclusive slot. @obj must be locked with dma_resv_lock().
> - * See also &dma_resv.fence_excl for a discussion of the semantics.
> + * Restart the unlocked iteration by initializing the cursor object.
> */
> -void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence)
> -{
> - struct dma_fence *old_fence = dma_resv_excl_fence(obj);
> -
> - dma_resv_assert_held(obj);
> -
> - dma_fence_get(fence);
> -
> - write_seqcount_begin(&obj->seq);
> - /* write_seqcount_begin provides the necessary memory barrier */
> - RCU_INIT_POINTER(obj->fence_excl, fence);
> - write_seqcount_end(&obj->seq);
> -
> - dma_fence_put(old_fence);
> -}
> -EXPORT_SYMBOL(dma_resv_add_excl_fence);
> -
> -/* Restart the iterator by initializing all the necessary fields, but not the
> - * relation to the dma_resv object. */
> static void dma_resv_iter_restart_unlocked(struct dma_resv_iter *cursor)
> {
> cursor->seq = read_seqcount_begin(&cursor->obj->seq);
> - cursor->index = -1;
> - cursor->shared_count = 0;
> - if (cursor->usage >= DMA_RESV_USAGE_READ) {
> - cursor->fences = dma_resv_shared_list(cursor->obj);
> - if (cursor->fences)
> - cursor->shared_count = cursor->fences->shared_count;
> - } else {
> - cursor->fences = NULL;
> - }
> + cursor->index = 0;
> + cursor->num_fences = 0;
> + cursor->fences = dma_resv_fences_list(cursor->obj);
> + if (cursor->fences)
> + cursor->num_fences = cursor->fences->num_fences;
> cursor->is_restarted = true;
> }
>
> /* Walk to the next not signaled fence and grab a reference to it */
> static void dma_resv_iter_walk_unlocked(struct dma_resv_iter *cursor)
> {
> - struct dma_resv *obj = cursor->obj;
> + if (!cursor->fences)
> + return;
>
> do {
> /* Drop the reference from the previous round */
> dma_fence_put(cursor->fence);
>
> - if (cursor->index == -1) {
> - cursor->fence = dma_resv_excl_fence(obj);
> - cursor->index++;
> - if (!cursor->fence)
> - continue;
> -
> - } else if (!cursor->fences ||
> - cursor->index >= cursor->shared_count) {
> + if (cursor->index >= cursor->num_fences) {
> cursor->fence = NULL;
> break;
>
> - } else {
> - struct dma_resv_list *fences = cursor->fences;
> - unsigned int idx = cursor->index++;
> -
> - cursor->fence = rcu_dereference(fences->shared[idx]);
> }
> +
> + dma_resv_list_entry(cursor->fences, cursor->index++,
> + cursor->obj, &cursor->fence,
> + &cursor->fence_usage);
> cursor->fence = dma_fence_get_rcu(cursor->fence);
> - if (!cursor->fence || !dma_fence_is_signaled(cursor->fence))
> + if (!cursor->fence)
> + break;
> +
> + if (!dma_fence_is_signaled(cursor->fence) &&
> + cursor->usage >= cursor->fence_usage)
> break;
> } while (true);
> }
> @@ -496,15 +496,9 @@ struct dma_fence *dma_resv_iter_first(struct dma_resv_iter *cursor)
> dma_resv_assert_held(cursor->obj);
>
> cursor->index = 0;
> - if (cursor->usage >= DMA_RESV_USAGE_READ)
> - cursor->fences = dma_resv_shared_list(cursor->obj);
> - else
> - cursor->fences = NULL;
> -
> - fence = dma_resv_excl_fence(cursor->obj);
> - if (!fence)
> - fence = dma_resv_iter_next(cursor);
> + cursor->fences = dma_resv_fences_list(cursor->obj);
>
> + fence = dma_resv_iter_next(cursor);
> cursor->is_restarted = true;
> return fence;
> }
> @@ -519,17 +513,17 @@ EXPORT_SYMBOL_GPL(dma_resv_iter_first);
> */
> struct dma_fence *dma_resv_iter_next(struct dma_resv_iter *cursor)
> {
> - unsigned int idx;
> + struct dma_fence *fence;
>
> dma_resv_assert_held(cursor->obj);
>
> cursor->is_restarted = false;
> - if (!cursor->fences || cursor->index >= cursor->fences->shared_count)
> + if (!cursor->fences || cursor->index >= cursor->fences->num_fences)
> return NULL;
>
> - idx = cursor->index++;
> - return rcu_dereference_protected(cursor->fences->shared[idx],
> - dma_resv_held(cursor->obj));
> + dma_resv_list_entry(cursor->fences, cursor->index++,
> + cursor->obj, &fence, &cursor->fence_usage);
Shouldn't we skip the current fence if cursor->fence_usage doesn't
match cursor->usage ? (similar to what is done wrt the unlocked
variant)
> + return fence;
> }
> EXPORT_SYMBOL_GPL(dma_resv_iter_next);
>
> @@ -544,57 +538,43 @@ int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src)
> {
> struct dma_resv_iter cursor;
> struct dma_resv_list *list;
> - struct dma_fence *f, *excl;
> + struct dma_fence *f;
>
> dma_resv_assert_held(dst);
>
> list = NULL;
> - excl = NULL;
>
> dma_resv_iter_begin(&cursor, src, DMA_RESV_USAGE_READ);
> dma_resv_for_each_fence_unlocked(&cursor, f) {
>
> if (dma_resv_iter_is_restarted(&cursor)) {
> dma_resv_list_free(list);
> - dma_fence_put(excl);
> -
> - if (cursor.shared_count) {
> - list = dma_resv_list_alloc(cursor.shared_count);
> - if (!list) {
> - dma_resv_iter_end(&cursor);
> - return -ENOMEM;
> - }
>
> - list->shared_count = 0;
> -
> - } else {
> - list = NULL;
> + list = dma_resv_list_alloc(cursor.num_fences);
> + if (!list) {
> + dma_resv_iter_end(&cursor);
> + return -ENOMEM;
> }
> - excl = NULL;
> + list->num_fences = 0;
> }
>
> dma_fence_get(f);
> - if (dma_resv_iter_is_exclusive(&cursor))
> - excl = f;
> - else
> - RCU_INIT_POINTER(list->shared[list->shared_count++], f);
> + dma_resv_list_set(list, list->num_fences++, f,
> + dma_resv_iter_usage(&cursor));
> }
> dma_resv_iter_end(&cursor);
>
> write_seqcount_begin(&dst->seq);
> - excl = rcu_replace_pointer(dst->fence_excl, excl, dma_resv_held(dst));
> - list = rcu_replace_pointer(dst->fence, list, dma_resv_held(dst));
> + list = rcu_replace_pointer(dst->fences, list, dma_resv_held(dst));
> write_seqcount_end(&dst->seq);
>
> dma_resv_list_free(list);
> - dma_fence_put(excl);
> -
> return 0;
> }
> EXPORT_SYMBOL(dma_resv_copy_fences);
>
> /**
> - * dma_resv_get_fences - Get an object's shared and exclusive
> + * dma_resv_get_fences - Get an object's fences
> * fences without update side lock held
> * @obj: the reservation object
> * @usage: controls which fences to include, see enum dma_resv_usage.
> @@ -623,7 +603,7 @@ int dma_resv_get_fences(struct dma_resv *obj, enum dma_resv_usage usage,
> while (*num_fences)
> dma_fence_put((*fences)[--(*num_fences)]);
>
> - count = cursor.shared_count + 1;
> + count = cursor.num_fences + 1;
>
> /* Eventually re-allocate the array */
> *fences = krealloc_array(*fences, count,
> @@ -695,8 +675,7 @@ int dma_resv_get_singleton(struct dma_resv *obj, enum dma_resv_usage usage,
> EXPORT_SYMBOL_GPL(dma_resv_get_singleton);
>
> /**
> - * dma_resv_wait_timeout - Wait on reservation's objects
> - * shared and/or exclusive fences.
> + * dma_resv_wait_timeout - Wait on reservation's objects fences
> * @obj: the reservation object
> * @usage: controls which fences to include, see enum dma_resv_usage.
> * @intr: if true, do interruptible wait
> @@ -769,13 +748,13 @@ EXPORT_SYMBOL_GPL(dma_resv_test_signaled);
> */
> void dma_resv_describe(struct dma_resv *obj, struct seq_file *seq)
> {
> + static const char *usage[] = { "kernel", "write", "read", "other" };
> struct dma_resv_iter cursor;
> struct dma_fence *fence;
>
> dma_resv_for_each_fence(&cursor, obj, true, fence) {
> seq_printf(seq, "\t%s fence:",
> - dma_resv_iter_is_exclusive(&cursor) ?
> - "Exclusive" : "Shared");
> + usage[dma_resv_iter_usage(&cursor)]);
> dma_fence_describe(fence, seq);
> }
> }
> diff --git a/drivers/dma-buf/st-dma-resv.c b/drivers/dma-buf/st-dma-resv.c
> index d097981061b1..d0f7c2bfd4f0 100644
> --- a/drivers/dma-buf/st-dma-resv.c
> +++ b/drivers/dma-buf/st-dma-resv.c
> @@ -58,8 +58,9 @@ static int sanitycheck(void *arg)
> return r;
> }
>
> -static int test_signaling(void *arg, enum dma_resv_usage usage)
> +static int test_signaling(void *arg)
> {
> + enum dma_resv_usage usage = (unsigned long)arg;
> struct dma_resv resv;
> struct dma_fence *f;
> int r;
> @@ -81,11 +82,7 @@ static int test_signaling(void *arg, enum dma_resv_usage usage)
> goto err_unlock;
> }
>
> - if (usage >= DMA_RESV_USAGE_READ)
> - dma_resv_add_shared_fence(&resv, f);
> - else
> - dma_resv_add_excl_fence(&resv, f);
> -
> + dma_resv_add_fence(&resv, f, usage);
> if (dma_resv_test_signaled(&resv, usage)) {
> pr_err("Resv unexpectedly signaled\n");
> r = -EINVAL;
> @@ -105,18 +102,9 @@ static int test_signaling(void *arg, enum dma_resv_usage usage)
> return r;
> }
>
> -static int test_excl_signaling(void *arg)
> -{
> - return test_signaling(arg, DMA_RESV_USAGE_WRITE);
> -}
> -
> -static int test_shared_signaling(void *arg)
> -{
> - return test_signaling(arg, DMA_RESV_USAGE_READ);
> -}
> -
> -static int test_for_each(void *arg, enum dma_resv_usage usage)
> +static int test_for_each(void *arg)
> {
> + enum dma_resv_usage usage = (unsigned long)arg;
> struct dma_resv_iter cursor;
> struct dma_fence *f, *fence;
> struct dma_resv resv;
> @@ -139,10 +127,7 @@ static int test_for_each(void *arg, enum dma_resv_usage usage)
> goto err_unlock;
> }
>
> - if (usage >= DMA_RESV_USAGE_READ)
> - dma_resv_add_shared_fence(&resv, f);
> - else
> - dma_resv_add_excl_fence(&resv, f);
> + dma_resv_add_fence(&resv, f, usage);
>
> r = -ENOENT;
> dma_resv_for_each_fence(&cursor, &resv, usage, fence) {
> @@ -156,8 +141,7 @@ static int test_for_each(void *arg, enum dma_resv_usage usage)
> r = -EINVAL;
> goto err_unlock;
> }
> - if (dma_resv_iter_is_exclusive(&cursor) !=
> - (usage >= DMA_RESV_USAGE_READ)) {
> + if (dma_resv_iter_usage(&cursor) != usage) {
> pr_err("Unexpected fence usage\n");
> r = -EINVAL;
> goto err_unlock;
> @@ -177,18 +161,9 @@ static int test_for_each(void *arg, enum dma_resv_usage usage)
> return r;
> }
>
> -static int test_excl_for_each(void *arg)
> -{
> - return test_for_each(arg, DMA_RESV_USAGE_WRITE);
> -}
> -
> -static int test_shared_for_each(void *arg)
> -{
> - return test_for_each(arg, DMA_RESV_USAGE_READ);
> -}
> -
> -static int test_for_each_unlocked(void *arg, enum dma_resv_usage usage)
> +static int test_for_each_unlocked(void *arg)
> {
> + enum dma_resv_usage usage = (unsigned long)arg;
> struct dma_resv_iter cursor;
> struct dma_fence *f, *fence;
> struct dma_resv resv;
> @@ -212,10 +187,7 @@ static int test_for_each_unlocked(void *arg, enum dma_resv_usage usage)
> goto err_free;
> }
>
> - if (usage >= DMA_RESV_USAGE_READ)
> - dma_resv_add_shared_fence(&resv, f);
> - else
> - dma_resv_add_excl_fence(&resv, f);
> + dma_resv_add_fence(&resv, f, usage);
> dma_resv_unlock(&resv);
>
> r = -ENOENT;
> @@ -235,8 +207,7 @@ static int test_for_each_unlocked(void *arg, enum dma_resv_usage usage)
> r = -EINVAL;
> goto err_iter_end;
> }
> - if (dma_resv_iter_is_exclusive(&cursor) !=
> - (usage >= DMA_RESV_USAGE_READ)) {
> + if (dma_resv_iter_usage(&cursor) != usage) {
> pr_err("Unexpected fence usage\n");
> r = -EINVAL;
> goto err_iter_end;
> @@ -262,18 +233,9 @@ static int test_for_each_unlocked(void *arg, enum dma_resv_usage usage)
> return r;
> }
>
> -static int test_excl_for_each_unlocked(void *arg)
> -{
> - return test_for_each_unlocked(arg, DMA_RESV_USAGE_WRITE);
> -}
> -
> -static int test_shared_for_each_unlocked(void *arg)
> -{
> - return test_for_each_unlocked(arg, DMA_RESV_USAGE_READ);
> -}
> -
> -static int test_get_fences(void *arg, enum dma_resv_usage usage)
> +static int test_get_fences(void *arg)
> {
> + enum dma_resv_usage usage = (unsigned long)arg;
> struct dma_fence *f, **fences = NULL;
> struct dma_resv resv;
> int r, i;
> @@ -296,10 +258,7 @@ static int test_get_fences(void *arg, enum dma_resv_usage usage)
> goto err_resv;
> }
>
> - if (usage >= DMA_RESV_USAGE_READ)
> - dma_resv_add_shared_fence(&resv, f);
> - else
> - dma_resv_add_excl_fence(&resv, f);
> + dma_resv_add_fence(&resv, f, usage);
> dma_resv_unlock(&resv);
>
> r = dma_resv_get_fences(&resv, usage, &i, &fences);
> @@ -324,30 +283,24 @@ static int test_get_fences(void *arg, enum dma_resv_usage usage)
> return r;
> }
>
> -static int test_excl_get_fences(void *arg)
> -{
> - return test_get_fences(arg, DMA_RESV_USAGE_WRITE);
> -}
> -
> -static int test_shared_get_fences(void *arg)
> -{
> - return test_get_fences(arg, DMA_RESV_USAGE_READ);
> -}
> -
> int dma_resv(void)
> {
> static const struct subtest tests[] = {
> SUBTEST(sanitycheck),
> - SUBTEST(test_excl_signaling),
> - SUBTEST(test_shared_signaling),
> - SUBTEST(test_excl_for_each),
> - SUBTEST(test_shared_for_each),
> - SUBTEST(test_excl_for_each_unlocked),
> - SUBTEST(test_shared_for_each_unlocked),
> - SUBTEST(test_excl_get_fences),
> - SUBTEST(test_shared_get_fences),
> + SUBTEST(test_signaling),
> + SUBTEST(test_for_each),
> + SUBTEST(test_for_each_unlocked),
> + SUBTEST(test_get_fences),
> };
> + enum dma_resv_usage usage;
> + int r;
>
> spin_lock_init(&fence_lock);
> - return subtests(tests, NULL);
> + for (usage = DMA_RESV_USAGE_WRITE; usage <= DMA_RESV_USAGE_READ;
> + ++usage) {
> + r = subtests(tests, (void *)(unsigned long)usage);
> + if (r)
> + return r;
> + }
> + return 0;
> }
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> index 7de8f67f7dde..ab5d6b630a49 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> @@ -263,7 +263,7 @@ static int amdgpu_amdkfd_remove_eviction_fence(struct amdgpu_bo *bo,
> */
> replacement = dma_fence_get_stub();
> dma_resv_replace_fences(bo->tbo.base.resv, ef->base.context,
> - replacement);
> + replacement, DMA_RESV_USAGE_READ);
> dma_fence_put(replacement);
> return 0;
> }
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> index 2bf909a4242a..1c039db976a9 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> @@ -54,8 +54,8 @@ static int amdgpu_cs_user_fence_chunk(struct amdgpu_cs_parser *p,
> bo = amdgpu_bo_ref(gem_to_amdgpu_bo(gobj));
> p->uf_entry.priority = 0;
> p->uf_entry.tv.bo = &bo->tbo;
> - /* One for TTM and one for the CS job */
> - p->uf_entry.tv.num_shared = 2;
> + /* One for TTM and two for the CS job */
> + p->uf_entry.tv.num_shared = 3;
>
> drm_gem_object_put(gobj);
>
> @@ -1284,7 +1284,7 @@ static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,
> break;
> }
> dma_fence_chain_init(chain, fence, dma_fence_get(p->fence), 1);
> - rcu_assign_pointer(resv->fence_excl, &chain->base);
> + dma_resv_add_fence(resv, &chain->base, DMA_RESV_USAGE_WRITE);
> e->chain = NULL;
> }
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> index 0a843cc54945..9085a6b1ad56 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> @@ -1393,10 +1393,8 @@ void amdgpu_bo_fence(struct amdgpu_bo *bo, struct dma_fence *fence,
> return;
> }
>
> - if (shared)
> - dma_resv_add_shared_fence(resv, fence);
> - else
> - dma_resv_add_excl_fence(resv, fence);
> + dma_resv_add_fence(resv, fence, shared ? DMA_RESV_USAGE_READ :
> + DMA_RESV_USAGE_WRITE);
> }
>
> /**
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c b/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
> index d7cd26dfaf8a..0cc036d93afc 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
> @@ -203,14 +203,10 @@ static void submit_attach_object_fences(struct etnaviv_gem_submit *submit)
>
> for (i = 0; i < submit->nr_bos; i++) {
> struct drm_gem_object *obj = &submit->bos[i].obj->base;
> + bool write = submit->bos[i].flags & ETNA_SUBMIT_BO_WRITE;
>
> - if (submit->bos[i].flags & ETNA_SUBMIT_BO_WRITE)
> - dma_resv_add_excl_fence(obj->resv,
> - submit->out_fence);
> - else
> - dma_resv_add_shared_fence(obj->resv,
> - submit->out_fence);
> -
> + dma_resv_add_fence(obj->resv, submit->out_fence, write ?
> + DMA_RESV_USAGE_WRITE : DMA_RESV_USAGE_READ);
> submit_unlock_object(submit, i);
> }
> }
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_busy.c b/drivers/gpu/drm/i915/gem/i915_gem_busy.c
> index 14a1c0ad8c3c..e7ae94ee1b44 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_busy.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_busy.c
> @@ -148,12 +148,13 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data,
> if (dma_resv_iter_is_restarted(&cursor))
> args->busy = 0;
>
> - if (dma_resv_iter_is_exclusive(&cursor))
> - /* Translate the exclusive fence to the READ *and* WRITE engine */
> - args->busy |= busy_check_writer(fence);
> - else
> - /* Translate shared fences to READ set of engines */
> - args->busy |= busy_check_reader(fence);
> + /* Translate read fences to READ set of engines */
> + args->busy |= busy_check_reader(fence);
> + }
> + dma_resv_iter_begin(&cursor, obj->base.resv, DMA_RESV_USAGE_WRITE);
> + dma_resv_for_each_fence_unlocked(&cursor, fence) {
> + /* Translate the write fences to the READ *and* WRITE engine */
> + args->busy |= busy_check_writer(fence);
> }
> dma_resv_iter_end(&cursor);
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_clflush.c b/drivers/gpu/drm/i915/gem/i915_gem_clflush.c
> index 8a2223eb0ba9..887cb6b71ae4 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_clflush.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_clflush.c
> @@ -114,7 +114,8 @@ bool i915_gem_clflush_object(struct drm_i915_gem_object *obj,
> obj->base.resv, NULL, true,
> i915_fence_timeout(i915),
> I915_FENCE_GFP);
> - dma_resv_add_excl_fence(obj->base.resv, &clflush->base.dma);
> + dma_resv_add_fence(obj->base.resv, &clflush->base.dma,
> + DMA_RESV_USAGE_WRITE);
> dma_fence_work_commit(&clflush->base);
> /*
> * We must have successfully populated the pages(since we are
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c
> index 4de6500f3c55..e4a232e22f9d 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c
> @@ -622,9 +622,8 @@ int i915_gem_obj_copy_ttm(struct drm_i915_gem_object *dst,
> if (IS_ERR_OR_NULL(copy_fence))
> return PTR_ERR_OR_ZERO(copy_fence);
>
> - dma_resv_add_excl_fence(dst_bo->base.resv, copy_fence);
> - dma_resv_add_shared_fence(src_bo->base.resv, copy_fence);
> -
> + dma_resv_add_fence(dst_bo->base.resv, copy_fence, DMA_RESV_USAGE_WRITE);
> + dma_resv_add_fence(src_bo->base.resv, copy_fence, DMA_RESV_USAGE_READ);
> dma_fence_put(copy_fence);
>
> return 0;
> diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
> index fe9f89289418..52fd6705a518 100644
> --- a/drivers/gpu/drm/i915/i915_vma.c
> +++ b/drivers/gpu/drm/i915/i915_vma.c
> @@ -1640,7 +1640,8 @@ int _i915_vma_move_to_active(struct i915_vma *vma,
> }
>
> if (fence) {
> - dma_resv_add_excl_fence(vma->obj->base.resv, fence);
> + dma_resv_add_fence(vma->obj->base.resv, fence,
> + DMA_RESV_USAGE_WRITE);
> obj->write_domain = I915_GEM_DOMAIN_RENDER;
> obj->read_domains = 0;
> }
> @@ -1652,7 +1653,8 @@ int _i915_vma_move_to_active(struct i915_vma *vma,
> }
>
> if (fence) {
> - dma_resv_add_shared_fence(vma->obj->base.resv, fence);
> + dma_resv_add_fence(vma->obj->base.resv, fence,
> + DMA_RESV_USAGE_READ);
> obj->write_domain = 0;
> }
> }
> diff --git a/drivers/gpu/drm/lima/lima_gem.c b/drivers/gpu/drm/lima/lima_gem.c
> index 9435a3ca71c8..38caa7f78871 100644
> --- a/drivers/gpu/drm/lima/lima_gem.c
> +++ b/drivers/gpu/drm/lima/lima_gem.c
> @@ -366,7 +366,7 @@ int lima_gem_submit(struct drm_file *file, struct lima_submit *submit)
> if (submit->bos[i].flags & LIMA_SUBMIT_BO_WRITE)
> dma_resv_add_excl_fence(lima_bo_resv(bos[i]), fence);
> else
> - dma_resv_add_shared_fence(lima_bo_resv(bos[i]), fence);
> + dma_resv_add_fence(lima_bo_resv(bos[i]), fence);
> }
>
> drm_gem_unlock_reservations((struct drm_gem_object **)bos,
> diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c
> index 993dbcd7a586..2786913be00a 100644
> --- a/drivers/gpu/drm/msm/msm_gem_submit.c
> +++ b/drivers/gpu/drm/msm/msm_gem_submit.c
> @@ -397,7 +397,7 @@ static void submit_attach_object_fences(struct msm_gem_submit *submit)
> if (submit->bos[i].flags & MSM_SUBMIT_BO_WRITE)
> dma_resv_add_excl_fence(obj->resv, submit->user_fence);
> else if (submit->bos[i].flags & MSM_SUBMIT_BO_READ)
> - dma_resv_add_shared_fence(obj->resv, submit->user_fence);
> + dma_resv_add_fence(obj->resv, submit->user_fence);
> }
> }
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c b/drivers/gpu/drm/nouveau/nouveau_bo.c
> index c6bb4dbcd735..05076e530e7d 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_bo.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_bo.c
> @@ -1308,10 +1308,11 @@ nouveau_bo_fence(struct nouveau_bo *nvbo, struct nouveau_fence *fence, bool excl
> {
> struct dma_resv *resv = nvbo->bo.base.resv;
>
> - if (exclusive)
> - dma_resv_add_excl_fence(resv, &fence->base);
> - else if (fence)
> - dma_resv_add_shared_fence(resv, &fence->base);
> + if (!fence)
> + return;
> +
> + dma_resv_add_fence(resv, &fence->base, exclusive ?
> + DMA_RESV_USAGE_WRITE : DMA_RESV_USAGE_READ);
> }
>
> static void
> diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.c b/drivers/gpu/drm/nouveau/nouveau_fence.c
> index d5e81ccee01c..7f01dcf81fab 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_fence.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_fence.c
> @@ -360,9 +360,11 @@ nouveau_fence_sync(struct nouveau_bo *nvbo, struct nouveau_channel *chan,
> dma_resv_for_each_fence(&cursor, resv,
> dma_resv_usage_rw(exclusive),
> fence) {
> + enum dma_resv_usage usage;
> struct nouveau_fence *f;
>
> - if (i == 0 && dma_resv_iter_is_exclusive(&cursor))
> + usage = dma_resv_iter_usage(&cursor);
> + if (i == 0 && usage == DMA_RESV_USAGE_WRITE)
> continue;
>
> f = nouveau_local_fence(fence, chan->drm);
> diff --git a/drivers/gpu/drm/qxl/qxl_release.c b/drivers/gpu/drm/qxl/qxl_release.c
> index cde1e8ddaeaa..368d26da0d6a 100644
> --- a/drivers/gpu/drm/qxl/qxl_release.c
> +++ b/drivers/gpu/drm/qxl/qxl_release.c
> @@ -429,7 +429,8 @@ void qxl_release_fence_buffer_objects(struct qxl_release *release)
> list_for_each_entry(entry, &release->bos, head) {
> bo = entry->bo;
>
> - dma_resv_add_shared_fence(bo->base.resv, &release->base);
> + dma_resv_add_fence(bo->base.resv, &release->base,
> + DMA_RESV_USAGE_READ);
> ttm_bo_move_to_lru_tail_unlocked(bo);
> dma_resv_unlock(bo->base.resv);
> }
> diff --git a/drivers/gpu/drm/radeon/radeon_object.c b/drivers/gpu/drm/radeon/radeon_object.c
> index afca4bf59a8d..382121c26f81 100644
> --- a/drivers/gpu/drm/radeon/radeon_object.c
> +++ b/drivers/gpu/drm/radeon/radeon_object.c
> @@ -792,8 +792,6 @@ void radeon_bo_fence(struct radeon_bo *bo, struct radeon_fence *fence,
> return;
> }
>
> - if (shared)
> - dma_resv_add_shared_fence(resv, &fence->base);
> - else
> - dma_resv_add_excl_fence(resv, &fence->base);
> + dma_resv_add_fence(resv, &fence->base, shared ?
> + DMA_RESV_USAGE_READ : DMA_RESV_USAGE_WRITE);
> }
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index d4b2695606e2..6014c363d6e6 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -762,7 +762,7 @@ static int ttm_bo_add_move_fence(struct ttm_buffer_object *bo,
> return ret;
> }
>
> - dma_resv_add_shared_fence(bo->base.resv, fence);
> + dma_resv_add_fence(bo->base.resv, fence, DMA_RESV_USAGE_WRITE);
>
> ret = dma_resv_reserve_fences(bo->base.resv, 1);
> if (unlikely(ret)) {
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
> index 862d2f22412a..49689c7c8078 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_util.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
> @@ -508,7 +508,8 @@ static int ttm_bo_move_to_ghost(struct ttm_buffer_object *bo,
> if (ret)
> return ret;
>
> - dma_resv_add_excl_fence(&ghost_obj->base._resv, fence);
> + dma_resv_add_fence(&ghost_obj->base._resv, fence,
> + DMA_RESV_USAGE_WRITE);
>
> /**
> * If we're not moving to fixed memory, the TTM object
> @@ -562,7 +563,7 @@ int ttm_bo_move_accel_cleanup(struct ttm_buffer_object *bo,
> struct ttm_resource_manager *man = ttm_manager_type(bdev, new_mem->mem_type);
> int ret = 0;
>
> - dma_resv_add_excl_fence(bo->base.resv, fence);
> + dma_resv_add_fence(bo->base.resv, fence, DMA_RESV_USAGE_WRITE);
> if (!evict)
> ret = ttm_bo_move_to_ghost(bo, fence, man->use_tt);
> else if (!from->use_tt && pipeline)
> diff --git a/drivers/gpu/drm/ttm/ttm_execbuf_util.c b/drivers/gpu/drm/ttm/ttm_execbuf_util.c
> index 789c645f004e..0eb995d25df1 100644
> --- a/drivers/gpu/drm/ttm/ttm_execbuf_util.c
> +++ b/drivers/gpu/drm/ttm/ttm_execbuf_util.c
> @@ -154,10 +154,8 @@ void ttm_eu_fence_buffer_objects(struct ww_acquire_ctx *ticket,
> list_for_each_entry(entry, list, head) {
> struct ttm_buffer_object *bo = entry->bo;
>
> - if (entry->num_shared)
> - dma_resv_add_shared_fence(bo->base.resv, fence);
> - else
> - dma_resv_add_excl_fence(bo->base.resv, fence);
> + dma_resv_add_fence(bo->base.resv, fence, entry->num_shared ?
> + DMA_RESV_USAGE_READ : DMA_RESV_USAGE_WRITE);
> ttm_bo_move_to_lru_tail_unlocked(bo);
> dma_resv_unlock(bo->base.resv);
> }
> diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/v3d_gem.c
> index 961812d33827..2352e9640922 100644
> --- a/drivers/gpu/drm/v3d/v3d_gem.c
> +++ b/drivers/gpu/drm/v3d/v3d_gem.c
> @@ -550,8 +550,8 @@ v3d_attach_fences_and_unlock_reservation(struct drm_file *file_priv,
>
> for (i = 0; i < job->bo_count; i++) {
> /* XXX: Use shared fences for read-only objects. */
> - dma_resv_add_excl_fence(job->bo[i]->resv,
> - job->done_fence);
> + dma_resv_add_fence(job->bo[i]->resv, job->done_fence,
> + DMA_RESV_USAGE_WRITE);
> }
>
> drm_gem_unlock_reservations(job->bo, job->bo_count, acquire_ctx);
> diff --git a/drivers/gpu/drm/vc4/vc4_gem.c b/drivers/gpu/drm/vc4/vc4_gem.c
> index 594bd6bb00d2..38550317e025 100644
> --- a/drivers/gpu/drm/vc4/vc4_gem.c
> +++ b/drivers/gpu/drm/vc4/vc4_gem.c
> @@ -546,7 +546,7 @@ vc4_update_bo_seqnos(struct vc4_exec_info *exec, uint64_t seqno)
> bo = to_vc4_bo(&exec->bo[i]->base);
> bo->seqno = seqno;
>
> - dma_resv_add_shared_fence(bo->base.base.resv, exec->fence);
> + dma_resv_add_fence(bo->base.base.resv, exec->fence);
> }
>
> list_for_each_entry(bo, &exec->unref_list, unref_head) {
> diff --git a/drivers/gpu/drm/vgem/vgem_fence.c b/drivers/gpu/drm/vgem/vgem_fence.c
> index 91fc4940c65a..c2a879734d40 100644
> --- a/drivers/gpu/drm/vgem/vgem_fence.c
> +++ b/drivers/gpu/drm/vgem/vgem_fence.c
> @@ -161,12 +161,9 @@ int vgem_fence_attach_ioctl(struct drm_device *dev,
> /* Expose the fence via the dma-buf */
> dma_resv_lock(resv, NULL);
> ret = dma_resv_reserve_fences(resv, 1);
> - if (!ret) {
> - if (arg->flags & VGEM_FENCE_WRITE)
> - dma_resv_add_excl_fence(resv, fence);
> - else
> - dma_resv_add_shared_fence(resv, fence);
> - }
> + if (!ret)
> + dma_resv_add_fence(resv, fence, arg->flags & VGEM_FENCE_WRITE ?
> + DMA_RESV_USAGE_WRITE : DMA_RESV_USAGE_READ);
> dma_resv_unlock(resv);
>
> /* Record the fence in our idr for later signaling */
> diff --git a/drivers/gpu/drm/virtio/virtgpu_gem.c b/drivers/gpu/drm/virtio/virtgpu_gem.c
> index 1820ca6cf673..580a78809836 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_gem.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_gem.c
> @@ -250,7 +250,8 @@ void virtio_gpu_array_add_fence(struct virtio_gpu_object_array *objs,
> int i;
>
> for (i = 0; i < objs->nents; i++)
> - dma_resv_add_excl_fence(objs->objs[i]->resv, fence);
> + dma_resv_add_fence(objs->objs[i]->resv, fence,
> + DMA_RESV_USAGE_WRITE);
> }
>
> void virtio_gpu_array_put_free(struct virtio_gpu_object_array *objs)
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_bo.c b/drivers/gpu/drm/vmwgfx/vmwgfx_bo.c
> index b96884f7d03d..bec50223efe5 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_bo.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_bo.c
> @@ -758,7 +758,8 @@ void vmw_bo_fence_single(struct ttm_buffer_object *bo,
>
> ret = dma_resv_reserve_fences(bo->base.resv, 1);
> if (!ret)
> - dma_resv_add_excl_fence(bo->base.resv, &fence->base);
> + dma_resv_add_fence(bo->base.resv, &fence->base,
> + DMA_RESV_USAGE_WRITE);
> else
> /* Last resort fallback when we are OOM */
> dma_fence_wait(&fence->base, false);
> diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
> index 74083e62e19d..a8cfc1705d6a 100644
> --- a/include/linux/dma-buf.h
> +++ b/include/linux/dma-buf.h
> @@ -393,16 +393,13 @@ struct dma_buf {
> * e.g. exposed in `Implicit Fence Poll Support`_ must follow the
> * below rules.
> *
> - * - Drivers must add a shared fence through dma_resv_add_shared_fence()
> - * for anything the userspace API considers a read access. This highly
> - * depends upon the API and window system.
> + * - Drivers must add a read fence through dma_resv_add_fence() with the
> + * DMA_RESV_USAGE_READ flag for anything the userspace API considers a
> + * read access. This highly depends upon the API and window system.
> *
> - * - Similarly drivers must set the exclusive fence through
> - * dma_resv_add_excl_fence() for anything the userspace API considers
> - * write access.
> - *
> - * - Drivers may just always set the exclusive fence, since that only
> - * causes unecessarily synchronization, but no correctness issues.
> + * - Similarly drivers must add a write fence through
> + * dma_resv_add_fence() with the DMA_RESV_USAGE_WRITE flag for
> + * anything the userspace API considers write access.
> *
> * - Some drivers only expose a synchronous userspace API with no
> * pipelining across drivers. These do not set any fences for their
> @@ -413,7 +410,7 @@ struct dma_buf {
> * Dynamic importers, see dma_buf_attachment_is_dynamic(), have
> * additional constraints on how they set up fences:
> *
> - * - Dynamic importers must obey the exclusive fence and wait for it to
> + * - Dynamic importers must obey the kernel fences and wait for them to
> * signal before allowing access to the buffer's underlying storage
> * through the device.
> *
> diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h
> index 658674c4b7b9..ae0436d7e7b8 100644
> --- a/include/linux/dma-resv.h
> +++ b/include/linux/dma-resv.h
> @@ -95,8 +95,8 @@ static inline enum dma_resv_usage dma_resv_usage_rw(bool write)
> /**
> * struct dma_resv - a reservation object manages fences for a buffer
> *
> - * There are multiple uses for this, with sometimes slightly different rules in
> - * how the fence slots are used.
> + * 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
> @@ -126,47 +126,22 @@ struct dma_resv {
> * @seq:
> *
> * Sequence count for managing RCU read-side synchronization, allows
> - * read-only access to @fence_excl and @fence while ensuring we take a
> - * consistent snapshot.
> + * read-only access to @fences while ensuring we take a consistent
> + * snapshot.
> */
> seqcount_ww_mutex_t seq;
>
> /**
> - * @fence_excl:
> + * @fences:
> *
> - * The exclusive fence, if there is one currently.
> + * Array of fences which where added to the dma_resv object
> *
> - * To guarantee that no fences are lost, this new fence must signal
> - * only after the previous exclusive fence has signalled. If
> - * semantically only a new access is added without actually treating the
> - * previous one as a dependency the exclusive fences can be strung
> - * together using struct dma_fence_chain.
> - *
> - * Note that actual semantics of what an exclusive or shared fence mean
> - * is defined by the user, for reservation objects shared across drivers
> - * see &dma_buf.resv.
> - */
> - struct dma_fence __rcu *fence_excl;
> -
> - /**
> - * @fence:
> - *
> - * List of current shared fences.
> - *
> - * There are no ordering constraints of shared fences against the
> - * exclusive fence slot. If a waiter needs to wait for all access, it
> - * has to wait for both sets of fences to signal.
> - *
> - * A new fence is added by calling dma_resv_add_shared_fence(). Since
> - * this often needs to be done past the point of no return in command
> + * 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().
> - *
> - * Note that actual semantics of what an exclusive or shared fence mean
> - * is defined by the user, for reservation objects shared across drivers
> - * see &dma_buf.resv.
> */
> - struct dma_resv_list __rcu *fence;
> + struct dma_resv_list __rcu *fences;
> };
>
> /**
> @@ -191,6 +166,9 @@ struct dma_resv_iter {
> /** @fence: the currently handled fence */
> struct dma_fence *fence;
>
> + /** @fence_usage: the usage of the current fence */
> + enum dma_resv_usage fence_usage;
> +
> /** @seq: sequence number to check for modifications */
> unsigned int seq;
>
> @@ -200,8 +178,8 @@ struct dma_resv_iter {
> /** @fences: the shared fences; private, *MUST* not dereference */
> struct dma_resv_list *fences;
>
> - /** @shared_count: number of shared fences */
> - unsigned int shared_count;
> + /** @num_fences: number of fences */
> + unsigned int num_fences;
>
> /** @is_restarted: true if this is the first returned fence */
> bool is_restarted;
> @@ -240,14 +218,15 @@ static inline void dma_resv_iter_end(struct dma_resv_iter *cursor)
> }
>
> /**
> - * dma_resv_iter_is_exclusive - test if the current fence is the exclusive one
> + * dma_resv_iter_usage - Return the usage of the current fence
> * @cursor: the cursor of the current position
> *
> - * Returns true if the currently returned fence is the exclusive one.
> + * Returns the usage of the currently processed fence.
> */
> -static inline bool dma_resv_iter_is_exclusive(struct dma_resv_iter *cursor)
> +static inline enum dma_resv_usage
> +dma_resv_iter_usage(struct dma_resv_iter *cursor)
> {
> - return cursor->index == 0;
> + return cursor->fence_usage;
> }
>
> /**
> @@ -302,9 +281,9 @@ static inline bool dma_resv_iter_is_restarted(struct dma_resv_iter *cursor)
> #define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)
>
> #ifdef CONFIG_DEBUG_MUTEXES
> -void dma_resv_reset_shared_max(struct dma_resv *obj);
> +void dma_resv_reset_max_fences(struct dma_resv *obj);
> #else
> -static inline void dma_resv_reset_shared_max(struct dma_resv *obj) {}
> +static inline void dma_resv_reset_max_fences(struct dma_resv *obj) {}
> #endif
>
> /**
> @@ -450,17 +429,18 @@ static inline struct ww_acquire_ctx *dma_resv_locking_ctx(struct dma_resv *obj)
> */
> static inline void dma_resv_unlock(struct dma_resv *obj)
> {
> - dma_resv_reset_shared_max(obj);
> + dma_resv_reset_max_fences(obj);
> ww_mutex_unlock(&obj->lock);
> }
>
> void dma_resv_init(struct dma_resv *obj);
> void dma_resv_fini(struct dma_resv *obj);
> int dma_resv_reserve_fences(struct dma_resv *obj, unsigned int num_fences);
> -void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence);
> +void dma_resv_add_fence(struct dma_resv *obj, struct dma_fence *fence,
> + enum dma_resv_usage usage);
> void dma_resv_replace_fences(struct dma_resv *obj, uint64_t context,
> - struct dma_fence *fence);
> -void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence);
> + struct dma_fence *fence,
> + enum dma_resv_usage usage);
> int dma_resv_get_fences(struct dma_resv *obj, enum dma_resv_usage usage,
> unsigned int *num_fences, struct dma_fence ***fences);
> int dma_resv_get_singleton(struct dma_resv *obj, enum dma_resv_usage usage,
> --
> 2.25.1
>
