[Intel-gfx] [PATCH 04/26] drm/i915: Add an implementation for i915_gem_ww_ctx locking, v2.
Maarten Lankhorst
maarten.lankhorst at linux.intel.com
Mon Jun 29 13:44:36 UTC 2020
Op 29-06-2020 om 14:32 schreef Tvrtko Ursulin:
>
> On 23/06/2020 15:28, Maarten Lankhorst wrote:
>> i915_gem_ww_ctx is used to lock all gem bo's for pinning and memory
>> eviction. We don't use it yet, but lets start adding the definition
>> first.
>>
>> To use it, we have to pass a non-NULL ww to gem_object_lock, and don't
>> unlock directly. It is done in i915_gem_ww_ctx_fini.
>>
>> Changes since v1:
>> - Change ww_ctx and obj order in locking functions (Jonas Lahtinen)
>>
>> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
>> ---
>> drivers/gpu/drm/i915/display/intel_display.c | 4 +-
>> .../gpu/drm/i915/gem/i915_gem_client_blt.c | 2 +-
>> drivers/gpu/drm/i915/gem/i915_gem_context.c | 2 +-
>> drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 4 +-
>> drivers/gpu/drm/i915/gem/i915_gem_domain.c | 10 ++--
>> .../gpu/drm/i915/gem/i915_gem_execbuffer.c | 4 +-
>> drivers/gpu/drm/i915/gem/i915_gem_object.c | 2 +-
>> drivers/gpu/drm/i915/gem/i915_gem_object.h | 38 +++++++++++---
>> .../gpu/drm/i915/gem/i915_gem_object_types.h | 9 ++++
>> drivers/gpu/drm/i915/gem/i915_gem_pm.c | 2 +-
>> drivers/gpu/drm/i915/gem/i915_gem_tiling.c | 2 +-
>> .../gpu/drm/i915/gem/selftests/huge_pages.c | 2 +-
>> .../i915/gem/selftests/i915_gem_client_blt.c | 2 +-
>> .../i915/gem/selftests/i915_gem_coherency.c | 10 ++--
>> .../drm/i915/gem/selftests/i915_gem_context.c | 4 +-
>> .../drm/i915/gem/selftests/i915_gem_mman.c | 4 +-
>> .../drm/i915/gem/selftests/i915_gem_phys.c | 2 +-
>> .../gpu/drm/i915/gt/selftest_workarounds.c | 2 +-
>> drivers/gpu/drm/i915/gvt/cmd_parser.c | 2 +-
>> drivers/gpu/drm/i915/i915_gem.c | 52 +++++++++++++++++--
>> drivers/gpu/drm/i915/i915_gem.h | 11 ++++
>> drivers/gpu/drm/i915/selftests/i915_gem.c | 41 +++++++++++++++
>> drivers/gpu/drm/i915/selftests/i915_vma.c | 2 +-
>> .../drm/i915/selftests/intel_memory_region.c | 2 +-
>> 24 files changed, 173 insertions(+), 42 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
>> index 7457813ef273..e909ccc37a54 100644
>> --- a/drivers/gpu/drm/i915/display/intel_display.c
>> +++ b/drivers/gpu/drm/i915/display/intel_display.c
>> @@ -2309,7 +2309,7 @@ intel_pin_and_fence_fb_obj(struct drm_framebuffer *fb,
>> void intel_unpin_fb_vma(struct i915_vma *vma, unsigned long flags)
>> {
>> - i915_gem_object_lock(vma->obj);
>> + i915_gem_object_lock(vma->obj, NULL);
>> if (flags & PLANE_HAS_FENCE)
>> i915_vma_unpin_fence(vma);
>> i915_gem_object_unpin_from_display_plane(vma);
>> @@ -17112,7 +17112,7 @@ static int intel_framebuffer_init(struct intel_framebuffer *intel_fb,
>> if (!intel_fb->frontbuffer)
>> return -ENOMEM;
>> - i915_gem_object_lock(obj);
>> + i915_gem_object_lock(obj, NULL);
>> tiling = i915_gem_object_get_tiling(obj);
>> stride = i915_gem_object_get_stride(obj);
>> i915_gem_object_unlock(obj);
>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_client_blt.c b/drivers/gpu/drm/i915/gem/i915_gem_client_blt.c
>> index d3a86a4d5c04..c182091c00ff 100644
>> --- a/drivers/gpu/drm/i915/gem/i915_gem_client_blt.c
>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_client_blt.c
>> @@ -286,7 +286,7 @@ int i915_gem_schedule_fill_pages_blt(struct drm_i915_gem_object *obj,
>> dma_fence_init(&work->dma, &clear_pages_work_ops, &fence_lock, 0, 0);
>> i915_sw_fence_init(&work->wait, clear_pages_work_notify);
>> - i915_gem_object_lock(obj);
>> + i915_gem_object_lock(obj, NULL);
>> err = i915_sw_fence_await_reservation(&work->wait,
>> obj->base.resv, NULL, true, 0,
>> I915_FENCE_GFP);
>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
>> index 30c229fcb404..a996583640ee 100644
>> --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
>> @@ -113,7 +113,7 @@ static void lut_close(struct i915_gem_context *ctx)
>> continue;
>> rcu_read_unlock();
>> - i915_gem_object_lock(obj);
>> + i915_gem_object_lock(obj, NULL);
>> list_for_each_entry(lut, &obj->lut_list, obj_link) {
>> if (lut->ctx != ctx)
>> continue;
>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
>> index 2679380159fc..27fddc22a7c6 100644
>> --- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
>> @@ -128,7 +128,7 @@ static int i915_gem_begin_cpu_access(struct dma_buf *dma_buf, enum dma_data_dire
>> if (err)
>> return err;
>> - err = i915_gem_object_lock_interruptible(obj);
>> + err = i915_gem_object_lock_interruptible(obj, NULL);
>> if (err)
>> goto out;
>> @@ -149,7 +149,7 @@ static int i915_gem_end_cpu_access(struct dma_buf *dma_buf, enum dma_data_direct
>> if (err)
>> return err;
>> - err = i915_gem_object_lock_interruptible(obj);
>> + err = i915_gem_object_lock_interruptible(obj, NULL);
>> if (err)
>> goto out;
>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_domain.c b/drivers/gpu/drm/i915/gem/i915_gem_domain.c
>> index 7f76fc68f498..c0acfc97fae3 100644
>> --- a/drivers/gpu/drm/i915/gem/i915_gem_domain.c
>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_domain.c
>> @@ -32,7 +32,7 @@ void i915_gem_object_flush_if_display(struct drm_i915_gem_object *obj)
>> if (!i915_gem_object_is_framebuffer(obj))
>> return;
>> - i915_gem_object_lock(obj);
>> + i915_gem_object_lock(obj, NULL);
>> __i915_gem_object_flush_for_display(obj);
>> i915_gem_object_unlock(obj);
>> }
>> @@ -197,7 +197,7 @@ int i915_gem_object_set_cache_level(struct drm_i915_gem_object *obj,
>> if (ret)
>> return ret;
>> - ret = i915_gem_object_lock_interruptible(obj);
>> + ret = i915_gem_object_lock_interruptible(obj, NULL);
>> if (ret)
>> return ret;
>> @@ -536,7 +536,7 @@ i915_gem_set_domain_ioctl(struct drm_device *dev, void *data,
>> if (err)
>> goto out;
>> - err = i915_gem_object_lock_interruptible(obj);
>> + err = i915_gem_object_lock_interruptible(obj, NULL);
>> if (err)
>> goto out_unpin;
>> @@ -576,7 +576,7 @@ int i915_gem_object_prepare_read(struct drm_i915_gem_object *obj,
>> if (!i915_gem_object_has_struct_page(obj))
>> return -ENODEV;
>> - ret = i915_gem_object_lock_interruptible(obj);
>> + ret = i915_gem_object_lock_interruptible(obj, NULL);
>> if (ret)
>> return ret;
>> @@ -630,7 +630,7 @@ int i915_gem_object_prepare_write(struct drm_i915_gem_object *obj,
>> if (!i915_gem_object_has_struct_page(obj))
>> return -ENODEV;
>> - ret = i915_gem_object_lock_interruptible(obj);
>> + ret = i915_gem_object_lock_interruptible(obj, NULL);
>> if (ret)
>> return ret;
>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
>> index 2b4c210638c1..391d22051b20 100644
>> --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
>> @@ -813,7 +813,7 @@ static int __eb_add_lut(struct i915_execbuffer *eb,
>> if (err == 0) { /* And nor has this handle */
>> struct drm_i915_gem_object *obj = vma->obj;
>> - i915_gem_object_lock(obj);
>> + i915_gem_object_lock(obj, NULL);
>> if (idr_find(&eb->file->object_idr, handle) == obj) {
>> list_add(&lut->obj_link, &obj->lut_list);
>> } else {
>> @@ -1083,7 +1083,7 @@ static void *reloc_iomap(struct drm_i915_gem_object *obj,
>> if (use_cpu_reloc(cache, obj))
>> return NULL;
>> - i915_gem_object_lock(obj);
>> + i915_gem_object_lock(obj, NULL);
>> err = i915_gem_object_set_to_gtt_domain(obj, true);
>> i915_gem_object_unlock(obj);
>> if (err)
>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.c b/drivers/gpu/drm/i915/gem/i915_gem_object.c
>> index b6ec5b50d93b..b59e2d40c347 100644
>> --- a/drivers/gpu/drm/i915/gem/i915_gem_object.c
>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_object.c
>> @@ -108,7 +108,7 @@ void i915_gem_close_object(struct drm_gem_object *gem, struct drm_file *file)
>> struct i915_lut_handle *lut, *ln;
>> LIST_HEAD(close);
>> - i915_gem_object_lock(obj);
>> + i915_gem_object_lock(obj, NULL);
>> list_for_each_entry_safe(lut, ln, &obj->lut_list, obj_link) {
>> struct i915_gem_context *ctx = lut->ctx;
>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h
>> index 2faa481cc18f..5103067269b0 100644
>> --- a/drivers/gpu/drm/i915/gem/i915_gem_object.h
>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h
>> @@ -110,20 +110,44 @@ i915_gem_object_put(struct drm_i915_gem_object *obj)
>> #define assert_object_held(obj) dma_resv_assert_held((obj)->base.resv)
>> -static inline void i915_gem_object_lock(struct drm_i915_gem_object *obj)
>> +static inline int __i915_gem_object_lock(struct drm_i915_gem_object *obj,
>> + struct i915_gem_ww_ctx *ww,
>> + bool intr)
>> {
>> - dma_resv_lock(obj->base.resv, NULL);
>> + int ret;
>> +
>> + if (intr)
>> + ret = dma_resv_lock_interruptible(obj->base.resv, ww ? &ww->ctx : NULL);
>> + else
>> + ret = dma_resv_lock(obj->base.resv, ww ? &ww->ctx : NULL);
>> +
>> + if (!ret && ww)
>> + list_add_tail(&obj->obj_link, &ww->obj_list);
>> + if (ret == -EALREADY)
>> + ret = 0;
>> +
>> + if (ret == -EDEADLK)
>> + ww->contended = obj;
>> +
>> + return ret;
>
> Feels a bit on the large side for inline now, no? Quite a few conditionals. Or you are counting on compiler optimisation because ww and intr are passed in as mostly const?
Slightly, not sure if it's really a problem in practice. ww is either null or a stack variable, so for null it should all go away.
>
>> }
>> -static inline bool i915_gem_object_trylock(struct drm_i915_gem_object *obj)
>> +static inline int i915_gem_object_lock(struct drm_i915_gem_object *obj,
>> + struct i915_gem_ww_ctx *ww)
>> {
>> - return dma_resv_trylock(obj->base.resv);
>> + return __i915_gem_object_lock(obj, ww, ww && ww->intr);
>> }
>> -static inline int
>> -i915_gem_object_lock_interruptible(struct drm_i915_gem_object *obj)
>> +static inline int i915_gem_object_lock_interruptible(struct drm_i915_gem_object *obj,
>> + struct i915_gem_ww_ctx *ww)
>> {
>> - return dma_resv_lock_interruptible(obj->base.resv, NULL);
>> + WARN_ON(ww && !ww->intr);
>> + return __i915_gem_object_lock(obj, ww, true);
>
> I see that ww->intr is set at ctx init time. At what times it is expected that the individual lock calls would override that?
Never. :) Just politely allowing it when replacing calls. Could be removed and replaced with lock_single_interruptible without ww context.
>
>> +}
>> +
>> +static inline bool i915_gem_object_trylock(struct drm_i915_gem_object *obj)
>> +{
>> + return dma_resv_trylock(obj->base.resv);
>> }
>> static inline void i915_gem_object_unlock(struct drm_i915_gem_object *obj)
>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
>> index b1f82a11aef2..3740c0080e38 100644
>> --- a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
>> @@ -122,6 +122,15 @@ struct drm_i915_gem_object {
>> */
>> struct list_head lut_list;
>> + /**
>> + * @obj_link: Link into @i915_gem_ww_ctx.obj_list
>> + *
>> + * When we lock this object through i915_gem_object_lock() with a
>> + * context, we add it to the list to ensure we can unlock everything
>> + * when i915_gem_ww_ctx_backoff() or i915_gem_ww_ctx_fini() are called.
>> + */
>> + struct list_head obj_link;
>> +
>> /** Stolen memory for this object, instead of being backed by shmem. */
>> struct drm_mm_node *stolen;
>> union {
>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_pm.c b/drivers/gpu/drm/i915/gem/i915_gem_pm.c
>> index 3d215164dd5a..40d3e40500fa 100644
>> --- a/drivers/gpu/drm/i915/gem/i915_gem_pm.c
>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_pm.c
>> @@ -84,7 +84,7 @@ void i915_gem_suspend_late(struct drm_i915_private *i915)
>> spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
>> - i915_gem_object_lock(obj);
>> + i915_gem_object_lock(obj, NULL);
>> drm_WARN_ON(&i915->drm,
>> i915_gem_object_set_to_gtt_domain(obj, false));
>> i915_gem_object_unlock(obj);
>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_tiling.c b/drivers/gpu/drm/i915/gem/i915_gem_tiling.c
>> index 0158e49bf9bb..65fbf29c4852 100644
>> --- a/drivers/gpu/drm/i915/gem/i915_gem_tiling.c
>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_tiling.c
>> @@ -249,7 +249,7 @@ i915_gem_object_set_tiling(struct drm_i915_gem_object *obj,
>> * whilst executing a fenced command for an untiled object.
>> */
>> - i915_gem_object_lock(obj);
>> + i915_gem_object_lock(obj, NULL);
>> if (i915_gem_object_is_framebuffer(obj)) {
>> i915_gem_object_unlock(obj);
>> return -EBUSY;
>> diff --git a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
>> index 8291ede6902c..eb2011ccb92b 100644
>> --- a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
>> +++ b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
>> @@ -947,7 +947,7 @@ static int gpu_write(struct intel_context *ce,
>> {
>> int err;
>> - i915_gem_object_lock(vma->obj);
>> + i915_gem_object_lock(vma->obj, NULL);
>> err = i915_gem_object_set_to_gtt_domain(vma->obj, true);
>> i915_gem_object_unlock(vma->obj);
>> if (err)
>> diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_client_blt.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_client_blt.c
>> index 299c29e9ad86..4e36d4897ea6 100644
>> --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_client_blt.c
>> +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_client_blt.c
>> @@ -75,7 +75,7 @@ static int __igt_client_fill(struct intel_engine_cs *engine)
>> if (err)
>> goto err_unpin;
>> - i915_gem_object_lock(obj);
>> + i915_gem_object_lock(obj, NULL);
>> err = i915_gem_object_set_to_cpu_domain(obj, false);
>> i915_gem_object_unlock(obj);
>> if (err)
>> diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c
>> index 87d7d8aa080f..1de2959b153c 100644
>> --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c
>> +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c
>> @@ -82,7 +82,7 @@ static int gtt_set(struct context *ctx, unsigned long offset, u32 v)
>> u32 __iomem *map;
>> int err = 0;
>> - i915_gem_object_lock(ctx->obj);
>> + i915_gem_object_lock(ctx->obj, NULL);
>> err = i915_gem_object_set_to_gtt_domain(ctx->obj, true);
>> i915_gem_object_unlock(ctx->obj);
>> if (err)
>> @@ -115,7 +115,7 @@ static int gtt_get(struct context *ctx, unsigned long offset, u32 *v)
>> u32 __iomem *map;
>> int err = 0;
>> - i915_gem_object_lock(ctx->obj);
>> + i915_gem_object_lock(ctx->obj, NULL);
>> err = i915_gem_object_set_to_gtt_domain(ctx->obj, false);
>> i915_gem_object_unlock(ctx->obj);
>> if (err)
>> @@ -147,7 +147,7 @@ static int wc_set(struct context *ctx, unsigned long offset, u32 v)
>> u32 *map;
>> int err;
>> - i915_gem_object_lock(ctx->obj);
>> + i915_gem_object_lock(ctx->obj, NULL);
>> err = i915_gem_object_set_to_wc_domain(ctx->obj, true);
>> i915_gem_object_unlock(ctx->obj);
>> if (err)
>> @@ -170,7 +170,7 @@ static int wc_get(struct context *ctx, unsigned long offset, u32 *v)
>> u32 *map;
>> int err;
>> - i915_gem_object_lock(ctx->obj);
>> + i915_gem_object_lock(ctx->obj, NULL);
>> err = i915_gem_object_set_to_wc_domain(ctx->obj, false);
>> i915_gem_object_unlock(ctx->obj);
>> if (err)
>> @@ -193,7 +193,7 @@ static int gpu_set(struct context *ctx, unsigned long offset, u32 v)
>> u32 *cs;
>> int err;
>> - i915_gem_object_lock(ctx->obj);
>> + i915_gem_object_lock(ctx->obj, NULL);
>> err = i915_gem_object_set_to_gtt_domain(ctx->obj, true);
>> i915_gem_object_unlock(ctx->obj);
>> if (err)
>> diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c
>> index b81978890641..438c15ef2184 100644
>> --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c
>> +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c
>> @@ -950,7 +950,7 @@ emit_rpcs_query(struct drm_i915_gem_object *obj,
>> if (IS_ERR(vma))
>> return PTR_ERR(vma);
>> - i915_gem_object_lock(obj);
>> + i915_gem_object_lock(obj, NULL);
>> err = i915_gem_object_set_to_gtt_domain(obj, false);
>> i915_gem_object_unlock(obj);
>> if (err)
>> @@ -1706,7 +1706,7 @@ static int read_from_scratch(struct i915_gem_context *ctx,
>> i915_request_add(rq);
>> - i915_gem_object_lock(obj);
>> + i915_gem_object_lock(obj, NULL);
>> err = i915_gem_object_set_to_cpu_domain(obj, false);
>> i915_gem_object_unlock(obj);
>> if (err)
>> 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 9c7402ce5bf9..9fb95a45bcad 100644
>> --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
>> +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
>> @@ -103,7 +103,7 @@ static int check_partial_mapping(struct drm_i915_gem_object *obj,
>> GEM_BUG_ON(i915_gem_object_get_tiling(obj) != tile->tiling);
>> GEM_BUG_ON(i915_gem_object_get_stride(obj) != tile->stride);
>> - i915_gem_object_lock(obj);
>> + i915_gem_object_lock(obj, NULL);
>> err = i915_gem_object_set_to_gtt_domain(obj, true);
>> i915_gem_object_unlock(obj);
>> if (err) {
>> @@ -188,7 +188,7 @@ static int check_partial_mappings(struct drm_i915_gem_object *obj,
>> GEM_BUG_ON(i915_gem_object_get_tiling(obj) != tile->tiling);
>> GEM_BUG_ON(i915_gem_object_get_stride(obj) != tile->stride);
>> - i915_gem_object_lock(obj);
>> + i915_gem_object_lock(obj, NULL);
>> err = i915_gem_object_set_to_gtt_domain(obj, true);
>> i915_gem_object_unlock(obj);
>> if (err) {
>> diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_phys.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_phys.c
>> index 34932871b3a5..a94243dc4c5c 100644
>> --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_phys.c
>> +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_phys.c
>> @@ -44,7 +44,7 @@ static int mock_phys_object(void *arg)
>> }
>> /* Make the object dirty so that put_pages must do copy back the data */
>> - i915_gem_object_lock(obj);
>> + i915_gem_object_lock(obj, NULL);
>> err = i915_gem_object_set_to_gtt_domain(obj, true);
>> i915_gem_object_unlock(obj);
>> if (err) {
>> diff --git a/drivers/gpu/drm/i915/gt/selftest_workarounds.c b/drivers/gpu/drm/i915/gt/selftest_workarounds.c
>> index febc9e6692ba..61a0532d0f3d 100644
>> --- a/drivers/gpu/drm/i915/gt/selftest_workarounds.c
>> +++ b/drivers/gpu/drm/i915/gt/selftest_workarounds.c
>> @@ -214,7 +214,7 @@ static int check_whitelist(struct i915_gem_context *ctx,
>> return PTR_ERR(results);
>> err = 0;
>> - i915_gem_object_lock(results);
>> + i915_gem_object_lock(results, NULL);
>> intel_wedge_on_timeout(&wedge, engine->gt, HZ / 5) /* safety net! */
>> err = i915_gem_object_set_to_cpu_domain(results, false);
>> i915_gem_object_unlock(results);
>> diff --git a/drivers/gpu/drm/i915/gvt/cmd_parser.c b/drivers/gpu/drm/i915/gvt/cmd_parser.c
>> index f1940939260a..943c8d232703 100644
>> --- a/drivers/gpu/drm/i915/gvt/cmd_parser.c
>> +++ b/drivers/gpu/drm/i915/gvt/cmd_parser.c
>> @@ -2982,7 +2982,7 @@ static int shadow_indirect_ctx(struct intel_shadow_wa_ctx *wa_ctx)
>> goto put_obj;
>> }
>> - i915_gem_object_lock(obj);
>> + i915_gem_object_lock(obj, NULL);
>> ret = i915_gem_object_set_to_cpu_domain(obj, false);
>> i915_gem_object_unlock(obj);
>> if (ret) {
>> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
>> index 9aa3066cb75d..1e06752835e5 100644
>> --- a/drivers/gpu/drm/i915/i915_gem.c
>> +++ b/drivers/gpu/drm/i915/i915_gem.c
>> @@ -420,7 +420,7 @@ i915_gem_gtt_pread(struct drm_i915_gem_object *obj,
>> GEM_BUG_ON(!drm_mm_node_allocated(&node));
>> }
>> - ret = i915_gem_object_lock_interruptible(obj);
>> + ret = i915_gem_object_lock_interruptible(obj, NULL);
>> if (ret)
>> goto out_unpin;
>> @@ -619,7 +619,7 @@ i915_gem_gtt_pwrite_fast(struct drm_i915_gem_object *obj,
>> GEM_BUG_ON(!drm_mm_node_allocated(&node));
>> }
>> - ret = i915_gem_object_lock_interruptible(obj);
>> + ret = i915_gem_object_lock_interruptible(obj, NULL);
>> if (ret)
>> goto out_unpin;
>> @@ -1290,7 +1290,7 @@ int i915_gem_freeze_late(struct drm_i915_private *i915)
>> i915_gem_drain_freed_objects(i915);
>> list_for_each_entry(obj, &i915->mm.shrink_list, mm.link) {
>> - i915_gem_object_lock(obj);
>> + i915_gem_object_lock(obj, NULL);
>> drm_WARN_ON(&i915->drm,
>> i915_gem_object_set_to_cpu_domain(obj, true));
>> i915_gem_object_unlock(obj);
>> @@ -1344,6 +1344,52 @@ int i915_gem_open(struct drm_i915_private *i915, struct drm_file *file)
>> return ret;
>> }
>> +void i915_gem_ww_ctx_init(struct i915_gem_ww_ctx *ww, bool intr)
>> +{
>> + ww_acquire_init(&ww->ctx, &reservation_ww_class);
>> + INIT_LIST_HEAD(&ww->obj_list);
>> + ww->intr = intr;
>> + ww->contended = NULL;
>> +}
>> +
>> +static void i915_gem_ww_ctx_unlock_all(struct i915_gem_ww_ctx *ww)
>> +{
>> + struct drm_i915_gem_object *obj;
>> +
>> + while ((obj = list_first_entry_or_null(&ww->obj_list, struct drm_i915_gem_object, obj_link))) {
>
> I wanted to ask whether you think this is faster than for_each_list_entry, but then also realized you can optimise further by not bothering to list_del (since you know the whole list is going away). If you are not allowing ww ctx reuse you don't even need to re-init the list_head at the end.
>
>> + list_del(&obj->obj_link);
>> + i915_gem_object_unlock(obj);
>> + }
>> +}
>> +
>> +void i915_gem_ww_ctx_fini(struct i915_gem_ww_ctx *ww)
>> +{
>> + i915_gem_ww_ctx_unlock_all(ww);
>> + WARN_ON(ww->contended);
>
> Unless I am missing something this feels like a GEM_BUG_ON condition (translated: we should be confident after testing it is impossible to hit).
>
> Or it is allowed to not try the backoff on -EDEADLK? Backoff is the only place which resets the ww->contended, right? In this case WARN_ON would be wrong, but you probably did not went for this design. Should it be supported?
>
>> + ww_acquire_fini(&ww->ctx);
>> +}
>> +
>> +int __must_check i915_gem_ww_ctx_backoff(struct i915_gem_ww_ctx *ww)
>> +{
>> + int ret = 0;
>> +
>> + if (WARN_ON(!ww->contended))
>> + return -EINVAL;
>> +
>> + i915_gem_ww_ctx_unlock_all(ww);
>> + if (ww->intr)
>> + ret = dma_resv_lock_slow_interruptible(ww->contended->base.resv, &ww->ctx);
>> + else
>> + dma_resv_lock_slow(ww->contended->base.resv, &ww->ctx);
>> +
>> + if (!ret)
>> + list_add_tail(&ww->contended->obj_link, &ww->obj_list);
>> +
>> + ww->contended = NULL;
>> +
>> + return ret;
>> +}
>> +
>> #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
>> #include "selftests/mock_gem_device.c"
>> #include "selftests/i915_gem.c"
>> diff --git a/drivers/gpu/drm/i915/i915_gem.h b/drivers/gpu/drm/i915/i915_gem.h
>> index 1753c84d6c0d..988755dbf4be 100644
>> --- a/drivers/gpu/drm/i915/i915_gem.h
>> +++ b/drivers/gpu/drm/i915/i915_gem.h
>> @@ -116,4 +116,15 @@ static inline bool __tasklet_is_scheduled(struct tasklet_struct *t)
>> return test_bit(TASKLET_STATE_SCHED, &t->state);
>> }
>> +struct i915_gem_ww_ctx {
>> + struct ww_acquire_ctx ctx;
>> + struct list_head obj_list;
>> + bool intr;
>> + struct drm_i915_gem_object *contended;
>> +};
>> +
>> +void i915_gem_ww_ctx_init(struct i915_gem_ww_ctx *ctx, bool intr);
>> +void i915_gem_ww_ctx_fini(struct i915_gem_ww_ctx *ctx);
>> +int __must_check i915_gem_ww_ctx_backoff(struct i915_gem_ww_ctx *ctx);
>> +
>> #endif /* __I915_GEM_H__ */
>> diff --git a/drivers/gpu/drm/i915/selftests/i915_gem.c b/drivers/gpu/drm/i915/selftests/i915_gem.c
>> index 88d400b9df88..23a6132c5f4e 100644
>> --- a/drivers/gpu/drm/i915/selftests/i915_gem.c
>> +++ b/drivers/gpu/drm/i915/selftests/i915_gem.c
>> @@ -199,11 +199,52 @@ static int igt_gem_hibernate(void *arg)
>> return err;
>> }
>> +static int igt_gem_ww_ctx(void *arg)
>> +{
>> + struct drm_i915_private *i915 = arg;
>> + struct drm_i915_gem_object *obj, *obj2;
>> + struct i915_gem_ww_ctx ww;
>> + int err = 0;
>> +
>> + obj = i915_gem_object_create_internal(i915, PAGE_SIZE);
>> + if (IS_ERR(obj))
>> + return PTR_ERR(obj);
>> +
>> + obj2 = i915_gem_object_create_internal(i915, PAGE_SIZE);
>> + if (IS_ERR(obj)) {
>
> Wrong obj ^^^ vvv.
>
>> + err = PTR_ERR(obj);
>> + goto put1;
>> + }
>> +
>> + i915_gem_ww_ctx_init(&ww, true);
>
> Need to expand with non-interruptible, interruptible and mixed.
>
>> +retry:
>> + /* Lock the objects, twice for good measure (-EALREADY handling) */
>> + err = i915_gem_object_lock(obj, &ww);
>> + if (!err)
>> + err = i915_gem_object_lock_interruptible(obj, &ww);
>
> This is -EALREADY on the 1st pass.
>
>> + if (!err)
>> + err = i915_gem_object_lock_interruptible(obj2, &ww);
>> + if (!err)
>> + err = i915_gem_object_lock(obj2, &ww);
>
> And this is -EALREADY again?
>
>> +
>> + if (err == -EDEADLK) {
>
> How do we get here with a single locking context?
>
>> + err = i915_gem_ww_ctx_backoff(&ww);
>> + if (!err)
>> + goto retry;
>> + }
>> + i915_gem_ww_ctx_fini(&ww);
>> + i915_gem_object_put(obj2);
>> +put1:
>> + i915_gem_object_put(obj);
>> + return err;
>> +}
>> +
>> int i915_gem_live_selftests(struct drm_i915_private *i915)
>> {
>> static const struct i915_subtest tests[] = {
>> SUBTEST(igt_gem_suspend),
>> SUBTEST(igt_gem_hibernate),
>> + SUBTEST(igt_gem_ww_ctx),
>> };
>> if (intel_gt_is_wedged(&i915->gt))
>> diff --git a/drivers/gpu/drm/i915/selftests/i915_vma.c b/drivers/gpu/drm/i915/selftests/i915_vma.c
>> index af89c7fc8f59..88c5e9acb84c 100644
>> --- a/drivers/gpu/drm/i915/selftests/i915_vma.c
>> +++ b/drivers/gpu/drm/i915/selftests/i915_vma.c
>> @@ -892,7 +892,7 @@ static int igt_vma_remapped_gtt(void *arg)
>> unsigned int x, y;
>> int err;
>> - i915_gem_object_lock(obj);
>> + i915_gem_object_lock(obj, NULL);
>> err = i915_gem_object_set_to_gtt_domain(obj, true);
>> i915_gem_object_unlock(obj);
>> if (err)
>> diff --git a/drivers/gpu/drm/i915/selftests/intel_memory_region.c b/drivers/gpu/drm/i915/selftests/intel_memory_region.c
>> index 6e80d99048e4..957a7a52def7 100644
>> --- a/drivers/gpu/drm/i915/selftests/intel_memory_region.c
>> +++ b/drivers/gpu/drm/i915/selftests/intel_memory_region.c
>> @@ -509,7 +509,7 @@ static int igt_lmem_write_cpu(void *arg)
>> if (err)
>> goto out_unpin;
>> - i915_gem_object_lock(obj);
>> + i915_gem_object_lock(obj, NULL);
>> err = i915_gem_object_set_to_wc_domain(obj, true);
>> i915_gem_object_unlock(obj);
>> if (err)
>>
>
> Regards,
>
> Tvrtko
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