Re: [PATCH 02/15] dma-buf: specify usage while adding fences to dma_resv obj v7

Daniel Vetter
2022-04-07T09:14:45Z

On Thu, Apr 07, 2022 at 10:59:33AM +0200, Christian König 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
> v6: separate internal dma_resv changes from this patch, avoids to
> disable warning temporary, rebase on upstream changes
> v7: fix missed case in lima driver, minimize changes to i915_gem_busy_ioctl

I've only done an incremental review of these two things, lgtm.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

>
> Signed-off-by: Christian König <christian.koenig@amd.com>
> ---
> drivers/dma-buf/dma-resv.c | 48 +++++++--
> 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 | 4 +-
> 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 | 6 +-
> drivers/gpu/drm/i915/gem/i915_gem_clflush.c | 3 +-
> drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c | 5 +-
> .../drm/i915/gem/selftests/i915_gem_migrate.c | 4 +-
> .../drm/i915/gem/selftests/i915_gem_mman.c | 3 +-
> drivers/gpu/drm/i915/i915_vma.c | 8 +-
> .../drm/i915/selftests/intel_memory_region.c | 3 +-
> drivers/gpu/drm/lima/lima_gem.c | 7 +-
> drivers/gpu/drm/msm/msm_gem_submit.c | 6 +-
> drivers/gpu/drm/nouveau/nouveau_bo.c | 9 +-
> drivers/gpu/drm/nouveau/nouveau_fence.c | 4 +-
> drivers/gpu/drm/panfrost/panfrost_job.c | 2 +-
> 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 | 16 +--
> include/linux/dma-resv.h | 25 +++--
> 30 files changed, 149 insertions(+), 166 deletions(-)
>
> diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
> index 17237e6ee30c..543dae6566d2 100644
> --- a/drivers/dma-buf/dma-resv.c
> +++ b/drivers/dma-buf/dma-resv.c
> @@ -234,14 +234,14 @@ 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 shared fences for debugging
> * @obj: the dma_resv object to reset
> *
> * Reset the number of pre-reserved shared slots to test that drivers do
> * correct slot allocation using dma_resv_reserve_fences(). See also
> * &dma_resv_list.shared_max.
> */
> -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);
>
> @@ -251,7 +251,7 @@ void dma_resv_reset_shared_max(struct dma_resv *obj)
> if (fences)
> fences->shared_max = fences->shared_count;
> }
> -EXPORT_SYMBOL(dma_resv_reset_shared_max);
> +EXPORT_SYMBOL(dma_resv_reset_max_fences);
> #endif
>
> /**
> @@ -264,7 +264,8 @@ EXPORT_SYMBOL(dma_resv_reset_shared_max);
> *
> * 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)
> +static void dma_resv_add_shared_fence(struct dma_resv *obj,
> + struct dma_fence *fence)
> {
> struct dma_resv_list *fobj;
> struct dma_fence *old;
> @@ -305,13 +306,13 @@ void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence)
> write_seqcount_end(&obj->seq);
> dma_fence_put(old);
> }
> -EXPORT_SYMBOL(dma_resv_add_shared_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
> @@ -321,12 +322,16 @@ 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;
>
> + /* Only readers supported for now */
> + WARN_ON(usage != DMA_RESV_USAGE_READ);
> +
> dma_resv_assert_held(obj);
>
> write_seqcount_begin(&obj->seq);
> @@ -360,7 +365,8 @@ EXPORT_SYMBOL(dma_resv_replace_fences);
> * 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.
> */
> -void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence)
> +static void dma_resv_add_excl_fence(struct dma_resv *obj,
> + struct dma_fence *fence)
> {
> struct dma_fence *old_fence = dma_resv_excl_fence(obj);
>
> @@ -375,7 +381,27 @@ void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence)
>
> dma_fence_put(old_fence);
> }
> -EXPORT_SYMBOL(dma_resv_add_excl_fence);
> +
> +/**
> + * dma_resv_add_fence - Add a fence to the dma_resv obj
> + * @obj: the reservation object
> + * @fence: the fence to add
> + * @usage: how the fence is used, see enum dma_resv_usage
> + *
> + * 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_fence(struct dma_resv *obj, struct dma_fence *fence,
> + enum dma_resv_usage usage)
> +{
> + if (usage == DMA_RESV_USAGE_WRITE)
> + dma_resv_add_excl_fence(obj, fence);
> + else
> + dma_resv_add_shared_fence(obj, fence);
> +}
> +EXPORT_SYMBOL(dma_resv_add_fence);
>
> /* Restart the iterator by initializing all the necessary fields, but not the
> * relation to the dma_resv object. */
> @@ -574,7 +600,7 @@ int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src)
> }
>
> dma_fence_get(f);
> - if (dma_resv_iter_is_exclusive(&cursor))
> + if (dma_resv_iter_usage(&cursor) == DMA_RESV_USAGE_WRITE)
> excl = f;
> else
> RCU_INIT_POINTER(list->shared[list->shared_count++], f);
> @@ -771,13 +797,13 @@ EXPORT_SYMBOL_GPL(dma_resv_test_signaled);
> */
> void dma_resv_describe(struct dma_resv *obj, struct seq_file *seq)
> {
> + static const char *usage[] = { "write", "read" };
> struct dma_resv_iter cursor;
> struct dma_fence *fence;
>
> dma_resv_for_each_fence(&cursor, obj, DMA_RESV_USAGE_READ, 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 98b1736bb221..5031e26e6716 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 413f32c3fd63..76fd916424d6 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> @@ -55,8 +55,8 @@ 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);
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> index a7f39f8ab7be..a3cdf8a24377 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> @@ -1397,10 +1397,8 @@ 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 53f7c78628a4..98bb5c9239de 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
> @@ -202,14 +202,10 @@ 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..ddda468241ef 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_busy.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_busy.c
> @@ -148,11 +148,11 @@ 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 */
> + if (dma_resv_iter_usage(&cursor) <= DMA_RESV_USAGE_WRITE)
> + /* Translate the write fences to the READ *and* WRITE engine */
> args->busy |= busy_check_writer(fence);
> else
> - /* Translate shared fences to READ set of engines */
> + /* Translate read fences to READ set of engines */
> args->busy |= busy_check_reader(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 1fd0cc9ca213..f5f2b8b115ea 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_clflush.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_clflush.c
> @@ -116,7 +116,8 @@ 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 432ac74ff225..438b8a95b3d1 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c
> @@ -637,9 +637,8 @@ 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/gem/selftests/i915_gem_migrate.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_migrate.c
> index 0e52eb87cd55..4997ed18b6e4 100644
> --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_migrate.c
> +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_migrate.c
> @@ -218,8 +218,8 @@ static int __igt_lmem_pages_migrate(struct intel_gt *gt,
> if (rq) {
> err = dma_resv_reserve_fences(obj->base.resv, 1);
> if (!err)
> - dma_resv_add_excl_fence(obj->base.resv,
> - &rq->fence);
> + dma_resv_add_fence(obj->base.resv, &rq->fence,
> + DMA_RESV_USAGE_WRITE);
> i915_gem_object_set_moving_fence(obj, &rq->fence);
> i915_request_put(rq);
> }
> diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
> index a132e241c3ee..3a6e3f6d239f 100644
> --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
> +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
> @@ -1220,7 +1220,8 @@ static int __igt_mmap_migrate(struct intel_memory_region **placements,
> expand32(POISON_INUSE), &rq);
> i915_gem_object_unpin_pages(obj);
> if (rq) {
> - dma_resv_add_excl_fence(obj->base.resv, &rq->fence);
> + dma_resv_add_fence(obj->base.resv, &rq->fence,
> + DMA_RESV_USAGE_WRITE);
> i915_gem_object_set_moving_fence(obj, &rq->fence);
> i915_request_put(rq);
> }
> diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
> index bae3423f58e8..524477d8939e 100644
> --- a/drivers/gpu/drm/i915/i915_vma.c
> +++ b/drivers/gpu/drm/i915/i915_vma.c
> @@ -1826,7 +1826,8 @@ 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;
> }
> @@ -1838,7 +1839,8 @@ 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;
> }
> }
> @@ -2078,7 +2080,7 @@ int i915_vma_unbind_async(struct i915_vma *vma, bool trylock_vm)
> goto out_rpm;
> }
>
> - dma_resv_add_shared_fence(obj->base.resv, fence);
> + dma_resv_add_fence(obj->base.resv, fence, DMA_RESV_USAGE_READ);
> dma_fence_put(fence);
>
> out_rpm:
> diff --git a/drivers/gpu/drm/i915/selftests/intel_memory_region.c b/drivers/gpu/drm/i915/selftests/intel_memory_region.c
> index 6114e013092b..73eb53edb8de 100644
> --- a/drivers/gpu/drm/i915/selftests/intel_memory_region.c
> +++ b/drivers/gpu/drm/i915/selftests/intel_memory_region.c
> @@ -1056,7 +1056,8 @@ static int igt_lmem_write_cpu(void *arg)
> obj->mm.pages->sgl, I915_CACHE_NONE,
> true, 0xdeadbeaf, &rq);
> if (rq) {
> - dma_resv_add_excl_fence(obj->base.resv, &rq->fence);
> + dma_resv_add_fence(obj->base.resv, &rq->fence,
> + DMA_RESV_USAGE_WRITE);
> i915_request_put(rq);
> }
>
> diff --git a/drivers/gpu/drm/lima/lima_gem.c b/drivers/gpu/drm/lima/lima_gem.c
> index e0a11ee0e86d..0f1ca0b0db49 100644
> --- a/drivers/gpu/drm/lima/lima_gem.c
> +++ b/drivers/gpu/drm/lima/lima_gem.c
> @@ -364,10 +364,9 @@ int lima_gem_submit(struct drm_file *file, struct lima_submit *submit)
> fence = lima_sched_context_queue_task(submit->task);
>
> for (i = 0; i < submit->nr_bos; i++) {
> - 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,
> + submit->bos[i].flags & LIMA_SUBMIT_BO_WRITE ?
> + DMA_RESV_USAGE_WRITE : DMA_RESV_USAGE_READ);
> }
>
> 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 3164db8be893..8d1eef914ba8 100644
> --- a/drivers/gpu/drm/msm/msm_gem_submit.c
> +++ b/drivers/gpu/drm/msm/msm_gem_submit.c
> @@ -395,9 +395,11 @@ static void submit_attach_object_fences(struct msm_gem_submit *submit)
> struct drm_gem_object *obj = &submit->bos[i].obj->base;
>
> if (submit->bos[i].flags & MSM_SUBMIT_BO_WRITE)
> - dma_resv_add_excl_fence(obj->resv, submit->user_fence);
> + dma_resv_add_fence(obj->resv, submit->user_fence,
> + DMA_RESV_USAGE_WRITE);
> 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,
> + DMA_RESV_USAGE_READ);
> }
> }
>
> 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/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
> index c34114560e49..fda5871aebe3 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_job.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_job.c
> @@ -268,7 +268,7 @@ static void panfrost_attach_object_fences(struct drm_gem_object **bos,
> int i;
>
> for (i = 0; i < bo_count; i++)
> - dma_resv_add_excl_fence(bos[i]->resv, fence);
> + dma_resv_add_fence(bos[i]->resv, fence, DMA_RESV_USAGE_WRITE);
> }
>
> int panfrost_job_push(struct panfrost_job *job)
> 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 7ffd2e90f325..cb5c4aa45cef 100644
> --- a/drivers/gpu/drm/radeon/radeon_object.c
> +++ b/drivers/gpu/drm/radeon/radeon_object.c
> @@ -791,8 +791,6 @@ 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 cff05b62f3f7..d74f9eea855e 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -739,7 +739,7 @@ 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 1b96b91bf81b..7a96a1db13a7 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_util.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
> @@ -507,7 +507,8 @@ 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
> @@ -561,7 +562,7 @@ 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 a297397743a2..71731796c8c3 100644
> --- a/include/linux/dma-buf.h
> +++ b/include/linux/dma-buf.h
> @@ -393,15 +393,15 @@ 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.
> + * - 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.
> *
> - * - Drivers may just always set the exclusive fence, since that only
> + * - Drivers may just always add a write fence, since that only
> * causes unecessarily synchronization, but no correctness issues.
> *
> * - Some drivers only expose a synchronous userspace API with no
> @@ -416,7 +416,7 @@ 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 write 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 92cd8023980f..98dc5234b487 100644
> --- a/include/linux/dma-resv.h
> +++ b/include/linux/dma-resv.h
> @@ -195,6 +195,9 @@ 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;
>
> @@ -244,14 +247,15 @@ 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;
> }
>
> /**
> @@ -306,9 +310,9 @@ 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
>
> /**
> @@ -454,17 +458,18 @@ 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
>

--
Daniel Vetter
Software Engineer, Intel Corporation