drm/i915: Finally remove obj->mm.lock.

With all callers and selftests fixed to use ww locking, we can now
finally remove this lock.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210323155059.628690-62-maarten.lankhorst@linux.intel.com

drivers/gpu/drm/i915/gem/i915_gem_object.c

@@ -62,8 +62,6 @@ void i915_gem_object_init(struct drm_i915_gem_object *obj,
 			  const struct drm_i915_gem_object_ops *ops,
 			  struct lock_class_key *key, unsigned flags)
 {
-	mutex_init(&obj->mm.lock);
-
 	spin_lock_init(&obj->vma.lock);
 	INIT_LIST_HEAD(&obj->vma.list);
 

drivers/gpu/drm/i915/gem/i915_gem_object.h

@@ -129,7 +129,7 @@ static inline void assert_object_held_shared(struct drm_i915_gem_object *obj)
 	 */
 	if (IS_ENABLED(CONFIG_LOCKDEP) &&
 	    kref_read(&obj->base.refcount) > 0)
-		lockdep_assert_held(&obj->mm.lock);
+		assert_object_held(obj);
 }
 
 static inline int __i915_gem_object_lock(struct drm_i915_gem_object *obj,
@@ -358,7 +358,7 @@ int __i915_gem_object_get_pages(struct drm_i915_gem_object *obj);
 static inline int __must_check
 i915_gem_object_pin_pages(struct drm_i915_gem_object *obj)
 {
-	might_lock(&obj->mm.lock);
+	assert_object_held(obj);
 
 	if (atomic_inc_not_zero(&obj->mm.pages_pin_count))
 		return 0;
@@ -404,7 +404,6 @@ i915_gem_object_unpin_pages(struct drm_i915_gem_object *obj)
 }
 
 int __i915_gem_object_put_pages(struct drm_i915_gem_object *obj);
-int __i915_gem_object_put_pages_locked(struct drm_i915_gem_object *obj);
 void i915_gem_object_truncate(struct drm_i915_gem_object *obj);
 void i915_gem_object_writeback(struct drm_i915_gem_object *obj);
 

drivers/gpu/drm/i915/gem/i915_gem_object_types.h

@@ -216,7 +216,6 @@ struct drm_i915_gem_object {
 		 * Protects the pages and their use. Do not use directly, but
 		 * instead go through the pin/unpin interfaces.
 		 */
-		struct mutex lock;
 		atomic_t pages_pin_count;
 		atomic_t shrink_pin;
 

drivers/gpu/drm/i915/gem/i915_gem_pages.c

@@ -70,7 +70,7 @@ void __i915_gem_object_set_pages(struct drm_i915_gem_object *obj,
 		struct list_head *list;
 		unsigned long flags;
 
-		lockdep_assert_held(&obj->mm.lock);
+		assert_object_held(obj);
 		spin_lock_irqsave(&i915->mm.obj_lock, flags);
 
 		i915->mm.shrink_count++;
@@ -117,9 +117,7 @@ int __i915_gem_object_get_pages(struct drm_i915_gem_object *obj)
 {
 	int err;
 
-	err = mutex_lock_interruptible(&obj->mm.lock);
-	if (err)
-		return err;
+	assert_object_held(obj);
 
 	assert_object_held_shared(obj);
 
@@ -128,15 +126,13 @@ int __i915_gem_object_get_pages(struct drm_i915_gem_object *obj)
 
 		err = ____i915_gem_object_get_pages(obj);
 		if (err)
-			goto unlock;
+			return err;
 
 		smp_mb__before_atomic();
 	}
 	atomic_inc(&obj->mm.pages_pin_count);
 
-unlock:
-	mutex_unlock(&obj->mm.lock);
-	return err;
+	return 0;
 }
 
 int i915_gem_object_pin_pages_unlocked(struct drm_i915_gem_object *obj)
@@ -223,7 +219,7 @@ __i915_gem_object_unset_pages(struct drm_i915_gem_object *obj)
 	return pages;
 }
 
-int __i915_gem_object_put_pages_locked(struct drm_i915_gem_object *obj)
+int __i915_gem_object_put_pages(struct drm_i915_gem_object *obj)
 {
 	struct sg_table *pages;
 
@@ -254,21 +250,6 @@ int __i915_gem_object_put_pages_locked(struct drm_i915_gem_object *obj)
 	return 0;
 }
 
-int __i915_gem_object_put_pages(struct drm_i915_gem_object *obj)
-{
-	int err;
-
-	if (i915_gem_object_has_pinned_pages(obj))
-		return -EBUSY;
-
-	/* May be called by shrinker from within get_pages() (on another bo) */
-	mutex_lock(&obj->mm.lock);
-	err = __i915_gem_object_put_pages_locked(obj);
-	mutex_unlock(&obj->mm.lock);
-
-	return err;
-}
-
 /* The 'mapping' part of i915_gem_object_pin_map() below */
 static void *i915_gem_object_map_page(struct drm_i915_gem_object *obj,
 				      enum i915_map_type type)
@@ -371,9 +352,7 @@ void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj,
 	    !i915_gem_object_type_has(obj, I915_GEM_OBJECT_HAS_IOMEM))
 		return ERR_PTR(-ENXIO);
 
-	err = mutex_lock_interruptible(&obj->mm.lock);
-	if (err)
-		return ERR_PTR(err);
+	assert_object_held(obj);
 
 	pinned = !(type & I915_MAP_OVERRIDE);
 	type &= ~I915_MAP_OVERRIDE;
@@ -383,10 +362,8 @@ void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj,
 			GEM_BUG_ON(i915_gem_object_has_pinned_pages(obj));
 
 			err = ____i915_gem_object_get_pages(obj);
-			if (err) {
-				ptr = ERR_PTR(err);
-				goto out_unlock;
-			}
+			if (err)
+				return ERR_PTR(err);
 
 			smp_mb__before_atomic();
 		}
@@ -421,13 +398,11 @@ void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj,
 		obj->mm.mapping = page_pack_bits(ptr, type);
 	}
 
-out_unlock:
-	mutex_unlock(&obj->mm.lock);
 	return ptr;
 
 err_unpin:
 	atomic_dec(&obj->mm.pages_pin_count);
-	goto out_unlock;
+	return ptr;
 }
 
 void *i915_gem_object_pin_map_unlocked(struct drm_i915_gem_object *obj,

drivers/gpu/drm/i915/gem/i915_gem_phys.c

@@ -234,40 +234,22 @@ int i915_gem_object_attach_phys(struct drm_i915_gem_object *obj, int align)
 	if (err)
 		return err;
 
-	err = mutex_lock_interruptible(&obj->mm.lock);
-	if (err)
-		return err;
-
-	if (unlikely(!i915_gem_object_has_struct_page(obj)))
-		goto out;
-
-	if (obj->mm.madv != I915_MADV_WILLNEED) {
-		err = -EFAULT;
-		goto out;
-	}
+	if (obj->mm.madv != I915_MADV_WILLNEED)
+		return -EFAULT;
 
-	if (i915_gem_object_has_tiling_quirk(obj)) {
-		err = -EFAULT;
-		goto out;
-	}
+	if (i915_gem_object_has_tiling_quirk(obj))
+		return -EFAULT;
 
-	if (obj->mm.mapping || i915_gem_object_has_pinned_pages(obj)) {
-		err = -EBUSY;
-		goto out;
-	}
+	if (obj->mm.mapping || i915_gem_object_has_pinned_pages(obj))
+		return -EBUSY;
 
 	if (unlikely(obj->mm.madv != I915_MADV_WILLNEED)) {
 		drm_dbg(obj->base.dev,
 			"Attempting to obtain a purgeable object\n");
-		err = -EFAULT;
-		goto out;
+		return -EFAULT;
 	}
 
-	err = i915_gem_object_shmem_to_phys(obj);
-
-out:
-	mutex_unlock(&obj->mm.lock);
-	return err;
+	return i915_gem_object_shmem_to_phys(obj);
 }
 
 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)

drivers/gpu/drm/i915/gem/i915_gem_pm.c

@@ -116,7 +116,7 @@ int i915_gem_freeze_late(struct drm_i915_private *i915)
 	 */
 
 	with_intel_runtime_pm(&i915->runtime_pm, wakeref)
-		i915_gem_shrink(i915, -1UL, NULL, ~0);
+		i915_gem_shrink(NULL, i915, -1UL, NULL, ~0);
 	i915_gem_drain_freed_objects(i915);
 
 	wbinvd_on_all_cpus();

drivers/gpu/drm/i915/gem/i915_gem_shmem.c

@@ -99,7 +99,7 @@ static int shmem_get_pages(struct drm_i915_gem_object *obj)
 				goto err_sg;
 			}
 
-			i915_gem_shrink(i915, 2 * page_count, NULL, *s++);
+			i915_gem_shrink(NULL, i915, 2 * page_count, NULL, *s++);
 
 			/*
 			 * We've tried hard to allocate the memory by reaping

drivers/gpu/drm/i915/gem/i915_gem_shrinker.c

@@ -94,7 +94,8 @@ static void try_to_writeback(struct drm_i915_gem_object *obj,
  * The number of pages of backing storage actually released.
  */
 unsigned long
-i915_gem_shrink(struct drm_i915_private *i915,
+i915_gem_shrink(struct i915_gem_ww_ctx *ww,
+		struct drm_i915_private *i915,
 		unsigned long target,
 		unsigned long *nr_scanned,
 		unsigned int shrink)
@@ -113,6 +114,7 @@ i915_gem_shrink(struct drm_i915_private *i915,
 	intel_wakeref_t wakeref = 0;
 	unsigned long count = 0;
 	unsigned long scanned = 0;
+	int err;
 
 	trace_i915_gem_shrink(i915, target, shrink);
 
@@ -200,25 +202,40 @@ i915_gem_shrink(struct drm_i915_private *i915,
 
 			spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
 
-			if (unsafe_drop_pages(obj, shrink) &&
-			    mutex_trylock(&obj->mm.lock)) {
+			err = 0;
+			if (unsafe_drop_pages(obj, shrink)) {
 				/* May arrive from get_pages on another bo */
-				if (!__i915_gem_object_put_pages_locked(obj)) {
+				if (!ww) {
+					if (!i915_gem_object_trylock(obj))
+						goto skip;
+				} else {
+					err = i915_gem_object_lock(obj, ww);
+					if (err)
+						goto skip;
+				}
+
+				if (!__i915_gem_object_put_pages(obj)) {
 					try_to_writeback(obj, shrink);
 					count += obj->base.size >> PAGE_SHIFT;
 				}
-				mutex_unlock(&obj->mm.lock);
+				if (!ww)
+					i915_gem_object_unlock(obj);
 			}
 
 			dma_resv_prune(obj->base.resv);
 
 			scanned += obj->base.size >> PAGE_SHIFT;
+skip:
 			i915_gem_object_put(obj);
 
 			spin_lock_irqsave(&i915->mm.obj_lock, flags);
+			if (err)
+				break;
 		}
 		list_splice_tail(&still_in_list, phase->list);
 		spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
+		if (err)
+			return err;
 	}
 
 	if (shrink & I915_SHRINK_BOUND)
@@ -249,7 +266,7 @@ unsigned long i915_gem_shrink_all(struct drm_i915_private *i915)
 	unsigned long freed = 0;
 
 	with_intel_runtime_pm(&i915->runtime_pm, wakeref) {
-		freed = i915_gem_shrink(i915, -1UL, NULL,
+		freed = i915_gem_shrink(NULL, i915, -1UL, NULL,
 					I915_SHRINK_BOUND |
 					I915_SHRINK_UNBOUND);
 	}
@@ -295,7 +312,7 @@ i915_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
 
 	sc->nr_scanned = 0;
 
-	freed = i915_gem_shrink(i915,
+	freed = i915_gem_shrink(NULL, i915,
 				sc->nr_to_scan,
 				&sc->nr_scanned,
 				I915_SHRINK_BOUND |
@@ -304,7 +321,7 @@ i915_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
 		intel_wakeref_t wakeref;
 
 		with_intel_runtime_pm(&i915->runtime_pm, wakeref) {
-			freed += i915_gem_shrink(i915,
+			freed += i915_gem_shrink(NULL, i915,
 						 sc->nr_to_scan - sc->nr_scanned,
 						 &sc->nr_scanned,
 						 I915_SHRINK_ACTIVE |
@@ -329,7 +346,7 @@ i915_gem_shrinker_oom(struct notifier_block *nb, unsigned long event, void *ptr)
 
 	freed_pages = 0;
 	with_intel_runtime_pm(&i915->runtime_pm, wakeref)
-		freed_pages += i915_gem_shrink(i915, -1UL, NULL,
+		freed_pages += i915_gem_shrink(NULL, i915, -1UL, NULL,
 					       I915_SHRINK_BOUND |
 					       I915_SHRINK_UNBOUND |
 					       I915_SHRINK_WRITEBACK);
@@ -367,7 +384,7 @@ i915_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr
 	intel_wakeref_t wakeref;
 
 	with_intel_runtime_pm(&i915->runtime_pm, wakeref)
-		freed_pages += i915_gem_shrink(i915, -1UL, NULL,
+		freed_pages += i915_gem_shrink(NULL, i915, -1UL, NULL,
 					       I915_SHRINK_BOUND |
 					       I915_SHRINK_UNBOUND |
 					       I915_SHRINK_VMAPS);

drivers/gpu/drm/i915/gem/i915_gem_shrinker.h

@@ -9,10 +9,12 @@
 #include <linux/bits.h>
 
 struct drm_i915_private;
+struct i915_gem_ww_ctx;
 struct mutex;
 
 /* i915_gem_shrinker.c */
-unsigned long i915_gem_shrink(struct drm_i915_private *i915,
+unsigned long i915_gem_shrink(struct i915_gem_ww_ctx *ww,
+			      struct drm_i915_private *i915,
 			      unsigned long target,
 			      unsigned long *nr_scanned,
 			      unsigned flags);

drivers/gpu/drm/i915/gem/i915_gem_tiling.c

@@ -265,7 +265,6 @@ i915_gem_object_set_tiling(struct drm_i915_gem_object *obj,
 	 * pages to prevent them being swapped out and causing corruption
 	 * due to the change in swizzling.
 	 */
-	mutex_lock(&obj->mm.lock);
 	if (i915_gem_object_has_pages(obj) &&
 	    obj->mm.madv == I915_MADV_WILLNEED &&
 	    i915->quirks & QUIRK_PIN_SWIZZLED_PAGES) {
@@ -280,7 +279,6 @@ i915_gem_object_set_tiling(struct drm_i915_gem_object *obj,
 			i915_gem_object_set_tiling_quirk(obj);
 		}
 	}
-	mutex_unlock(&obj->mm.lock);
 
 	spin_lock(&obj->vma.lock);
 	for_each_ggtt_vma(vma, obj) {

drivers/gpu/drm/i915/gem/i915_gem_userptr.c

@@ -253,15 +253,14 @@ static int i915_gem_object_userptr_unbind(struct drm_i915_gem_object *obj, bool
 	if (GEM_WARN_ON(i915_gem_object_has_pinned_pages(obj)))
 		return -EBUSY;
 
-	mutex_lock(&obj->mm.lock);
+	assert_object_held(obj);
 
 	pages = __i915_gem_object_unset_pages(obj);
 	if (!IS_ERR_OR_NULL(pages))
 		i915_gem_userptr_put_pages(obj, pages);
 
 	if (get_pages)
 		err = ____i915_gem_object_get_pages(obj);
-	mutex_unlock(&obj->mm.lock);
 
 	return err;
 }

drivers/gpu/drm/i915/i915_debugfs.c

@@ -904,10 +904,10 @@ i915_drop_caches_set(void *data, u64 val)
 
 	fs_reclaim_acquire(GFP_KERNEL);
 	if (val & DROP_BOUND)
-		i915_gem_shrink(i915, LONG_MAX, NULL, I915_SHRINK_BOUND);
+		i915_gem_shrink(NULL, i915, LONG_MAX, NULL, I915_SHRINK_BOUND);
 
 	if (val & DROP_UNBOUND)
-		i915_gem_shrink(i915, LONG_MAX, NULL, I915_SHRINK_UNBOUND);
+		i915_gem_shrink(NULL, i915, LONG_MAX, NULL, I915_SHRINK_UNBOUND);
 
 	if (val & DROP_SHRINK_ALL)
 		i915_gem_shrink_all(i915);