[PATCH 1/4] locking/ww_mutex: add ww_mutex_is_owned_by function

[PATCH 1/4] locking/ww_mutex: add ww_mutex_is_owned_by function

[Christian König]

amdgpu needs to verify if userspace sends us valid addresses and the simplest
way of doing this is to check if the buffer object is locked with the ticket
of the current submission.

Clean up the access to the ww_mutex internals by providing a function
for this and extend the check to the thread owning the underlying mutex.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 include/linux/ww_mutex.h | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/include/linux/ww_mutex.h b/include/linux/ww_mutex.h
index 39fda195bf78..dd580db289e8 100644
--- a/include/linux/ww_mutex.h
+++ b/include/linux/ww_mutex.h
@@ -358,4 +358,21 @@ static inline bool ww_mutex_is_locked(struct ww_mutex *lock)
 	return mutex_is_locked(&lock->base);
 }
 
+/**
+ * ww_mutex_is_owned_by - is the w/w mutex locked by this task in that context
+ * @lock: the mutex to be queried
+ * @task: the task structure to check
+ * @ctx: the w/w acquire context to test
+ *
+ * Returns true if the mutex is locked in the context by the given task, false
+ * otherwise.
+ */
+static inline bool ww_mutex_is_owned_by(struct ww_mutex *lock,
+					struct task_struct *task,
+					struct ww_acquire_ctx *ctx)
+{
+	return likely(__mutex_owner(&lock->base) == task) &&
+		READ_ONCE(lock->ctx) == ctx;
+}
+
 #endif
-- 
2.14.1

[PATCH 2/4] drm/amdgpu: use new ww_mutex_is_owned_by function

[Christian König]

Instead of accessing ww_mutex internals directly use the provided
function to check if the ww_mutex was indeed locked by the current
command submission.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
index eaa3cb0c3ad1..4c04b560e358 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
@@ -1594,7 +1594,8 @@ int amdgpu_cs_find_mapping(struct amdgpu_cs_parser *parser,
 	*map = mapping;
 
 	/* Double check that the BO is reserved by this CS */
-	if (READ_ONCE((*bo)->tbo.resv->lock.ctx) != &parser->ticket)
+	if (!ww_mutex_is_owned_by(&(*bo)->tbo.resv->lock, current,
+				  &parser->ticket))
 		return -EINVAL;
 
 	if (!((*bo)->flags & AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS)) {
-- 
2.14.1

[PATCH 3/4] drm/ttm: handle already locked BOs during eviction and swapout.

[Christian König]

This solves the problem that when we swapout a BO from a domain we
sometimes couldn't make room for it because holding the lock blocks all
other BOs with this reservation object.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/ttm/ttm_bo.c | 33 ++++++++++++++++-----------------
 1 file changed, 16 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index d90b1cf10b27..fba40e22d088 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -713,31 +713,30 @@ bool ttm_bo_eviction_valuable(struct ttm_buffer_object *bo,
 EXPORT_SYMBOL(ttm_bo_eviction_valuable);
 
 /**
- * Check the target bo is allowable to be evicted or swapout, including cases:
- *
- * a. if share same reservation object with ctx->resv, have assumption
- * reservation objects should already be locked, so not lock again and
- * return true directly when either the opreation allow_reserved_eviction
- * or the target bo already is in delayed free list;
- *
- * b. Otherwise, trylock it.
+ * Check if the target bo is allowed to be evicted or swapedout.
  */
 static bool ttm_bo_evict_swapout_allowable(struct ttm_buffer_object *bo,
-			struct ttm_operation_ctx *ctx, bool *locked)
+					   struct ttm_operation_ctx *ctx,
+					   bool *locked)
 {
-	bool ret = false;
+	/* First check if we can lock it */
+	*locked = reservation_object_trylock(bo->resv);
+	if (*locked)
+		return true;
 
-	*locked = false;
+	/* Check if it's locked because it is part of the current operation */
 	if (bo->resv == ctx->resv) {
 		reservation_object_assert_held(bo->resv);
-		if (ctx->allow_reserved_eviction || !list_empty(&bo->ddestroy))
-			ret = true;
-	} else {
-		*locked = reservation_object_trylock(bo->resv);
-		ret = *locked;
+		return ctx->allow_reserved_eviction ||
+			!list_empty(&bo->ddestroy);
 	}
 
-	return ret;
+	/* Check if it's locked because it was already evicted */
+	if (ww_mutex_is_owned_by(&bo->resv->lock, current, NULL))
+		return true;
+
+	/* Some other thread is using it, don't touch it */
+	return false;
 }
 
 static int ttm_mem_evict_first(struct ttm_bo_device *bdev,
-- 
2.14.1

[PATCH 4/4] drm/ttm: keep BOs reserved until end of eviction

[Christian König]

This avoids problems when BOs are evicted but directly moved back into
the domain from other threads.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/ttm/ttm_bo.c | 37 +++++++++++++++++++++++++++++--------
 1 file changed, 29 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index fba40e22d088..568cf216b374 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -742,7 +742,8 @@ static bool ttm_bo_evict_swapout_allowable(struct ttm_buffer_object *bo,
 static int ttm_mem_evict_first(struct ttm_bo_device *bdev,
 			       uint32_t mem_type,
 			       const struct ttm_place *place,
-			       struct ttm_operation_ctx *ctx)
+			       struct ttm_operation_ctx *ctx,
+			       struct list_head *evicted)
 {
 	struct ttm_bo_global *glob = bdev->glob;
 	struct ttm_mem_type_manager *man = &bdev->man[mem_type];
@@ -792,17 +793,28 @@ static int ttm_mem_evict_first(struct ttm_bo_device *bdev,
 
 	ret = ttm_bo_evict(bo, ctx);
 	if (locked) {
-		ttm_bo_unreserve(bo);
+		list_add_tail(&bo->lru, evicted);
 	} else {
 		spin_lock(&glob->lru_lock);
 		ttm_bo_add_to_lru(bo);
 		spin_unlock(&glob->lru_lock);
+		kref_put(&bo->list_kref, ttm_bo_release_list);
 	}
 
-	kref_put(&bo->list_kref, ttm_bo_release_list);
 	return ret;
 }
 
+static void ttm_mem_evict_cleanup(struct list_head *evicted)
+{
+	struct ttm_buffer_object *bo, *tmp;
+
+	list_for_each_entry_safe(bo, tmp, evicted, lru) {
+		list_del_init(&bo->lru);
+		ttm_bo_unreserve(bo);
+		kref_put(&bo->list_kref, ttm_bo_release_list);
+	}
+}
+
 void ttm_bo_mem_put(struct ttm_buffer_object *bo, struct ttm_mem_reg *mem)
 {
 	struct ttm_mem_type_manager *man = &bo->bdev->man[mem->mem_type];
@@ -852,20 +864,26 @@ static int ttm_bo_mem_force_space(struct ttm_buffer_object *bo,
 {
 	struct ttm_bo_device *bdev = bo->bdev;
 	struct ttm_mem_type_manager *man = &bdev->man[mem_type];
+	struct list_head evicted;
 	int ret;
 
+	INIT_LIST_HEAD(&evicted);
 	do {
 		ret = (*man->func->get_node)(man, bo, place, mem);
 		if (unlikely(ret != 0))
 			return ret;
 		if (mem->mm_node)
 			break;
-		ret = ttm_mem_evict_first(bdev, mem_type, place, ctx);
+		ret = ttm_mem_evict_first(bdev, mem_type, place, ctx, &evicted);
 		if (unlikely(ret != 0))
-			return ret;
+			goto error;
 	} while (1);
 	mem->mem_type = mem_type;
-	return ttm_bo_add_move_fence(bo, man, mem);
+	ret = ttm_bo_add_move_fence(bo, man, mem);
+
+error:
+	ttm_mem_evict_cleanup(&evicted);
+	return ret;
 }
 
 static uint32_t ttm_bo_select_caching(struct ttm_mem_type_manager *man,
@@ -1345,6 +1363,7 @@ static int ttm_bo_force_list_clean(struct ttm_bo_device *bdev,
 	struct ttm_operation_ctx ctx = { false, false };
 	struct ttm_mem_type_manager *man = &bdev->man[mem_type];
 	struct ttm_bo_global *glob = bdev->glob;
+	struct list_head evicted;
 	struct dma_fence *fence;
 	int ret;
 	unsigned i;
@@ -1352,18 +1371,20 @@ static int ttm_bo_force_list_clean(struct ttm_bo_device *bdev,
 	/*
 	 * Can't use standard list traversal since we're unlocking.
 	 */
-
+	INIT_LIST_HEAD(&evicted);
 	spin_lock(&glob->lru_lock);
 	for (i = 0; i < TTM_MAX_BO_PRIORITY; ++i) {
 		while (!list_empty(&man->lru[i])) {
 			spin_unlock(&glob->lru_lock);
-			ret = ttm_mem_evict_first(bdev, mem_type, NULL, &ctx);
+			ret = ttm_mem_evict_first(bdev, mem_type, NULL, &ctx,
+						  &evicted);
 			if (ret)
 				return ret;
 			spin_lock(&glob->lru_lock);
 		}
 	}
 	spin_unlock(&glob->lru_lock);
+	ttm_mem_evict_cleanup(&evicted);
 
 	spin_lock(&man->move_lock);
 	fence = dma_fence_get(man->move);
-- 
2.14.1

[PATCH 1/4] locking/ww_mutex: add ww_mutex_is_owned_by function v3

[Christian König]

amdgpu needs to verify if userspace sends us valid addresses and the simplest
way of doing this is to check if the buffer object is locked with the ticket
of the current submission.

Clean up the access to the ww_mutex internals by providing a function
for this and extend the check to the thread owning the underlying mutex.

v2: split amdgpu changes into separate patch as suggested by Alex
v3: change logic as suggested by Daniel

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 include/linux/ww_mutex.h | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/include/linux/ww_mutex.h b/include/linux/ww_mutex.h
index 39fda195bf78..14e4149d3d9d 100644
--- a/include/linux/ww_mutex.h
+++ b/include/linux/ww_mutex.h
@@ -358,4 +358,21 @@ static inline bool ww_mutex_is_locked(struct ww_mutex *lock)
 	return mutex_is_locked(&lock->base);
 }
 
+/**
+ * ww_mutex_is_owned_by - is the w/w mutex locked by this task in that context
+ * @lock: the mutex to be queried
+ * @ctx: the w/w acquire context to test
+ *
+ * If @ctx is not NULL test if the mutex is owned by this context.
+ * If @ctx is NULL test if the mutex is owned by the current thread.
+ */
+static inline bool ww_mutex_is_owned_by(struct ww_mutex *lock,
+					struct ww_acquire_ctx *ctx)
+{
+	if (ctx)
+		return likely(READ_ONCE(lock->ctx) == ctx);
+	else
+		return likely(__mutex_owner(&lock->base) == current);
+}
+
 #endif
-- 
2.14.1

[PATCH 2/4] drm/amdgpu: use new ww_mutex_is_owned_by function

[Christian König]

Instead of accessing ww_mutex internals directly use the provided
function to check if the ww_mutex was indeed locked by the current
command submission.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
index eaa3cb0c3ad1..6db26a3144dc 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
@@ -1594,7 +1594,7 @@ int amdgpu_cs_find_mapping(struct amdgpu_cs_parser *parser,
 	*map = mapping;
 
 	/* Double check that the BO is reserved by this CS */
-	if (READ_ONCE((*bo)->tbo.resv->lock.ctx) != &parser->ticket)
+	if (!ww_mutex_is_owned_by(&(*bo)->tbo.resv->lock, &parser->ticket))
 		return -EINVAL;
 
 	if (!((*bo)->flags & AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS)) {
-- 
2.14.1

RE: [PATCH 2/4] drm/amdgpu: use new ww_mutex_is_owned_by function

[He, Roger]

Reviewed-by: Roger He <Hongbo.He@amd.com>

-----Original Message-----
From: amd-gfx [mailto:amd-gfx-bounces@lists.freedesktop.org] On Behalf Of Christian K?nig
Sent: Tuesday, February 20, 2018 8:58 PM
To: amd-gfx@lists.freedesktop.org; dri-devel@lists.freedesktop.org; linux-kernel@vger.kernel.org
Subject: [PATCH 2/4] drm/amdgpu: use new ww_mutex_is_owned_by function

Instead of accessing ww_mutex internals directly use the provided function to check if the ww_mutex was indeed locked by the current command submission.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
index eaa3cb0c3ad1..6db26a3144dc 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
@@ -1594,7 +1594,7 @@ int amdgpu_cs_find_mapping(struct amdgpu_cs_parser *parser,
 	*map = mapping;
 
 	/* Double check that the BO is reserved by this CS */
-	if (READ_ONCE((*bo)->tbo.resv->lock.ctx) != &parser->ticket)
+	if (!ww_mutex_is_owned_by(&(*bo)->tbo.resv->lock, &parser->ticket))
 		return -EINVAL;
 
 	if (!((*bo)->flags & AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS)) {
--
2.14.1

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