diff --git a/drivers/gpu/drm/nouveau/nouveau_gem.c b/drivers/gpu/drm/nouveau/nouveau_gem.c
index 24e0aabda03c47109e869486f2b99fda77e30d33..d98bee012cab9ef84ae5835b383583af97c73ed1 100644
--- a/drivers/gpu/drm/nouveau/nouveau_gem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_gem.c
@@ -318,6 +318,7 @@ validate_init(struct nouveau_channel *chan, struct drm_file *file_priv,
uint32_t sequence;
int trycnt = 0;
int ret, i;
+ struct nouveau_bo *res_bo = NULL;
sequence = atomic_add_return(1, &drm->ttm.validate_sequence);
retry:
@@ -338,6 +339,11 @@ validate_init(struct nouveau_channel *chan, struct drm_file *file_priv,
return -ENOENT;
}
nvbo = gem->driver_private;
+ if (nvbo == res_bo) {
+ res_bo = NULL;
+ drm_gem_object_unreference_unlocked(gem);
+ continue;
+ }
if (nvbo->reserved_by && nvbo->reserved_by == file_priv) {
NV_ERROR(drm, "multiple instances of buffer %d on "
@@ -350,15 +356,19 @@ validate_init(struct nouveau_channel *chan, struct drm_file *file_priv,
ret = ttm_bo_reserve(&nvbo->bo, true, false, true, sequence);
if (ret) {
validate_fini(op, NULL);
- if (unlikely(ret == -EAGAIN))
- ret = ttm_bo_wait_unreserved(&nvbo->bo, true);
- drm_gem_object_unreference_unlocked(gem);
+ if (unlikely(ret == -EAGAIN)) {
+ sequence = atomic_add_return(1, &drm->ttm.validate_sequence);
+ ret = ttm_bo_reserve_slowpath(&nvbo->bo, true,
+ sequence);
+ if (!ret)
+ res_bo = nvbo;
+ }
if (unlikely(ret)) {
+ drm_gem_object_unreference_unlocked(gem);
if (ret != -ERESTARTSYS)
NV_ERROR(drm, "fail reserve\n");
return ret;
}
- goto retry;
}
b->user_priv = (uint64_t)(unsigned long)nvbo;
@@ -380,6 +390,8 @@ validate_init(struct nouveau_channel *chan, struct drm_file *file_priv,
validate_fini(op, NULL);
return -EINVAL;
}
+ if (nvbo == res_bo)
+ goto retry;
}
return 0;
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 52b20b12c83a3859da1b5fbbc1449fd3d4e907a4..9b07b7d44a58b318eb05727a0545a8325a1a5efd 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -158,7 +158,8 @@ static void ttm_bo_release_list(struct kref *list_kref)
ttm_mem_global_free(bdev->glob->mem_glob, acc_size);
}
-int ttm_bo_wait_unreserved(struct ttm_buffer_object *bo, bool interruptible)
+static int ttm_bo_wait_unreserved(struct ttm_buffer_object *bo,
+ bool interruptible)
{
if (interruptible) {
return wait_event_interruptible(bo->event_queue,
@@ -168,7 +169,6 @@ int ttm_bo_wait_unreserved(struct ttm_buffer_object *bo, bool interruptible)
return 0;
}
}
-EXPORT_SYMBOL(ttm_bo_wait_unreserved);
void ttm_bo_add_to_lru(struct ttm_buffer_object *bo)
{
@@ -213,14 +213,13 @@ int ttm_bo_del_from_lru(struct ttm_buffer_object *bo)
return put_count;
}
-int ttm_bo_reserve_locked(struct ttm_buffer_object *bo,
+int ttm_bo_reserve_nolru(struct ttm_buffer_object *bo,
bool interruptible,
bool no_wait, bool use_sequence, uint32_t sequence)
{
- struct ttm_bo_global *glob = bo->glob;
int ret;
- while (unlikely(atomic_read(&bo->reserved) != 0)) {
+ while (unlikely(atomic_xchg(&bo->reserved, 1) != 0)) {
/**
* Deadlock avoidance for multi-bo reserving.
*/
@@ -241,26 +240,36 @@ int ttm_bo_reserve_locked(struct ttm_buffer_object *bo,
if (no_wait)
return -EBUSY;
- spin_unlock(&glob->lru_lock);
ret = ttm_bo_wait_unreserved(bo, interruptible);
- spin_lock(&glob->lru_lock);
if (unlikely(ret))
return ret;
}
- atomic_set(&bo->reserved, 1);
if (use_sequence) {
+ bool wake_up = false;
/**
* Wake up waiters that may need to recheck for deadlock,
* if we decreased the sequence number.
*/
if (unlikely((bo->val_seq - sequence < (1 << 31))
|| !bo->seq_valid))
- wake_up_all(&bo->event_queue);
+ wake_up = true;
+ /*
+ * In the worst case with memory ordering these values can be
+ * seen in the wrong order. However since we call wake_up_all
+ * in that case, this will hopefully not pose a problem,
+ * and the worst case would only cause someone to accidentally
+ * hit -EAGAIN in ttm_bo_reserve when they see old value of
+ * val_seq. However this would only happen if seq_valid was
+ * written before val_seq was, and just means some slightly
+ * increased cpu usage
+ */
bo->val_seq = sequence;
bo->seq_valid = true;
+ if (wake_up)
+ wake_up_all(&bo->event_queue);
} else {
bo->seq_valid = false;
}
@@ -289,17 +298,64 @@ int ttm_bo_reserve(struct ttm_buffer_object *bo,
int put_count = 0;
int ret;
- spin_lock(&glob->lru_lock);
- ret = ttm_bo_reserve_locked(bo, interruptible, no_wait, use_sequence,
- sequence);
- if (likely(ret == 0))
+ ret = ttm_bo_reserve_nolru(bo, interruptible, no_wait, use_sequence,
+ sequence);
+ if (likely(ret == 0)) {
+ spin_lock(&glob->lru_lock);
put_count = ttm_bo_del_from_lru(bo);
- spin_unlock(&glob->lru_lock);
+ spin_unlock(&glob->lru_lock);
+ ttm_bo_list_ref_sub(bo, put_count, true);
+ }
- ttm_bo_list_ref_sub(bo, put_count, true);
+ return ret;
+}
+
+int ttm_bo_reserve_slowpath_nolru(struct ttm_buffer_object *bo,
+ bool interruptible, uint32_t sequence)
+{
+ bool wake_up = false;
+ int ret;
+
+ while (unlikely(atomic_xchg(&bo->reserved, 1) != 0)) {
+ WARN_ON(bo->seq_valid && sequence == bo->val_seq);
+
+ ret = ttm_bo_wait_unreserved(bo, interruptible);
+ if (unlikely(ret))
+ return ret;
+ }
+
+ if ((bo->val_seq - sequence < (1 << 31)) || !bo->seq_valid)
+ wake_up = true;
+
+ /**
+ * Wake up waiters that may need to recheck for deadlock,
+ * if we decreased the sequence number.
+ */
+ bo->val_seq = sequence;
+ bo->seq_valid = true;
+ if (wake_up)
+ wake_up_all(&bo->event_queue);
+
+ return 0;
+}
+
+int ttm_bo_reserve_slowpath(struct ttm_buffer_object *bo,
+ bool interruptible, uint32_t sequence)
+{
+ struct ttm_bo_global *glob = bo->glob;
+ int put_count, ret;
+
+ ret = ttm_bo_reserve_slowpath_nolru(bo, interruptible, sequence);
+ if (likely(!ret)) {
+ spin_lock(&glob->lru_lock);
+ put_count = ttm_bo_del_from_lru(bo);
+ spin_unlock(&glob->lru_lock);
+ ttm_bo_list_ref_sub(bo, put_count, true);
+ }
return ret;
}
+EXPORT_SYMBOL(ttm_bo_reserve_slowpath);
void ttm_bo_unreserve_locked(struct ttm_buffer_object *bo)
{
@@ -511,7 +567,7 @@ static void ttm_bo_cleanup_refs_or_queue(struct ttm_buffer_object *bo)
int ret;
spin_lock(&glob->lru_lock);
- ret = ttm_bo_reserve_locked(bo, false, true, false, 0);
+ ret = ttm_bo_reserve_nolru(bo, false, true, false, 0);
spin_lock(&bdev->fence_lock);
(void) ttm_bo_wait(bo, false, false, true);
@@ -604,7 +660,7 @@ static int ttm_bo_cleanup_refs_and_unlock(struct ttm_buffer_object *bo,
return ret;
spin_lock(&glob->lru_lock);
- ret = ttm_bo_reserve_locked(bo, false, true, false, 0);
+ ret = ttm_bo_reserve_nolru(bo, false, true, false, 0);
/*
* We raced, and lost, someone else holds the reservation now,
@@ -668,7 +724,14 @@ static int ttm_bo_delayed_delete(struct ttm_bo_device *bdev, bool remove_all)
kref_get(&nentry->list_kref);
}
- ret = ttm_bo_reserve_locked(entry, false, !remove_all, false, 0);
+ ret = ttm_bo_reserve_nolru(entry, false, true, false, 0);
+ if (remove_all && ret) {
+ spin_unlock(&glob->lru_lock);
+ ret = ttm_bo_reserve_nolru(entry, false, false,
+ false, 0);
+ spin_lock(&glob->lru_lock);
+ }
+
if (!ret)
ret = ttm_bo_cleanup_refs_and_unlock(entry, false,
!remove_all);
@@ -816,7 +879,7 @@ static int ttm_mem_evict_first(struct ttm_bo_device *bdev,
spin_lock(&glob->lru_lock);
list_for_each_entry(bo, &man->lru, lru) {
- ret = ttm_bo_reserve_locked(bo, false, true, false, 0);
+ ret = ttm_bo_reserve_nolru(bo, false, true, false, 0);
if (!ret)
break;
}
@@ -1797,7 +1860,7 @@ static int ttm_bo_swapout(struct ttm_mem_shrink *shrink)
spin_lock(&glob->lru_lock);
list_for_each_entry(bo, &glob->swap_lru, swap) {
- ret = ttm_bo_reserve_locked(bo, false, true, false, 0);
+ ret = ttm_bo_reserve_nolru(bo, false, true, false, 0);
if (!ret)
break;
}
diff --git a/drivers/gpu/drm/ttm/ttm_execbuf_util.c b/drivers/gpu/drm/ttm/ttm_execbuf_util.c
index cd9e4523dc561efaf0208689a90a4790b4dab986..7b90def15674d8e9b99c11e2011287b3f992a742 100644
--- a/drivers/gpu/drm/ttm/ttm_execbuf_util.c
+++ b/drivers/gpu/drm/ttm/ttm_execbuf_util.c
@@ -82,22 +82,6 @@ static void ttm_eu_list_ref_sub(struct list_head *list)
}
}
-static int ttm_eu_wait_unreserved_locked(struct list_head *list,
- struct ttm_buffer_object *bo)
-{
- struct ttm_bo_global *glob = bo->glob;
- int ret;
-
- ttm_eu_del_from_lru_locked(list);
- spin_unlock(&glob->lru_lock);
- ret = ttm_bo_wait_unreserved(bo, true);
- spin_lock(&glob->lru_lock);
- if (unlikely(ret != 0))
- ttm_eu_backoff_reservation_locked(list);
- return ret;
-}
-
-
void ttm_eu_backoff_reservation(struct list_head *list)
{
struct ttm_validate_buffer *entry;
@@ -145,47 +129,65 @@ int ttm_eu_reserve_buffers(struct list_head *list)
entry = list_first_entry(list, struct ttm_validate_buffer, head);
glob = entry->bo->glob;
-retry:
spin_lock(&glob->lru_lock);
val_seq = entry->bo->bdev->val_seq++;
+retry:
list_for_each_entry(entry, list, head) {
struct ttm_buffer_object *bo = entry->bo;
-retry_this_bo:
- ret = ttm_bo_reserve_locked(bo, true, true, true, val_seq);
+ /* already slowpath reserved? */
+ if (entry->reserved)
+ continue;
+
+ ret = ttm_bo_reserve_nolru(bo, true, true, true, val_seq);
switch (ret) {
case 0:
break;
case -EBUSY:
- ret = ttm_eu_wait_unreserved_locked(list, bo);
- if (unlikely(ret != 0)) {
- spin_unlock(&glob->lru_lock);
- ttm_eu_list_ref_sub(list);
- return ret;
- }
- goto retry_this_bo;
+ ttm_eu_del_from_lru_locked(list);
+ spin_unlock(&glob->lru_lock);
+ ret = ttm_bo_reserve_nolru(bo, true, false,
+ true, val_seq);
+ spin_lock(&glob->lru_lock);
+ if (!ret)
+ break;
+
+ if (unlikely(ret != -EAGAIN))
+ goto err;
+
+ /* fallthrough */
case -EAGAIN:
ttm_eu_backoff_reservation_locked(list);
+
+ /*
+ * temporarily increase sequence number every retry,
+ * to prevent us from seeing our old reservation
+ * sequence when someone else reserved the buffer,
+ * but hasn't updated the seq_valid/seqno members yet.
+ */
+ val_seq = entry->bo->bdev->val_seq++;
+
spin_unlock(&glob->lru_lock);
ttm_eu_list_ref_sub(list);
- ret = ttm_bo_wait_unreserved(bo, true);
+ ret = ttm_bo_reserve_slowpath_nolru(bo, true, val_seq);
if (unlikely(ret != 0))
return ret;
+ spin_lock(&glob->lru_lock);
+ entry->reserved = true;
+ if (unlikely(atomic_read(&bo->cpu_writers) > 0)) {
+ ret = -EBUSY;
+ goto err;
+ }
goto retry;
default:
- ttm_eu_backoff_reservation_locked(list);
- spin_unlock(&glob->lru_lock);
- ttm_eu_list_ref_sub(list);
- return ret;
+ goto err;
}
entry->reserved = true;
if (unlikely(atomic_read(&bo->cpu_writers) > 0)) {
- ttm_eu_backoff_reservation_locked(list);
- spin_unlock(&glob->lru_lock);
- ttm_eu_list_ref_sub(list);
- return -EBUSY;
+ ret = -EBUSY;
+ goto err;
}
}
@@ -194,6 +196,12 @@ int ttm_eu_reserve_buffers(struct list_head *list)
ttm_eu_list_ref_sub(list);
return 0;
+
+err:
+ ttm_eu_backoff_reservation_locked(list);
+ spin_unlock(&glob->lru_lock);
+ ttm_eu_list_ref_sub(list);
+ return ret;
}
EXPORT_SYMBOL(ttm_eu_reserve_buffers);
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
index e01a17b407b2e642e2f7b5f3596f4b2e8af00755..16556170fb32e663cf7e80f004488206571fba0e 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
@@ -959,13 +959,13 @@ void vmw_resource_unreserve(struct vmw_resource *res,
if (new_backup && new_backup != res->backup) {
if (res->backup) {
- BUG_ON(atomic_read(&res->backup->base.reserved) == 0);
+ BUG_ON(!ttm_bo_is_reserved(&res->backup->base));
list_del_init(&res->mob_head);
vmw_dmabuf_unreference(&res->backup);
}
res->backup = vmw_dmabuf_reference(new_backup);
- BUG_ON(atomic_read(&new_backup->base.reserved) == 0);
+ BUG_ON(!ttm_bo_is_reserved(&new_backup->base));
list_add_tail(&res->mob_head, &new_backup->res_list);
}
if (new_backup)
diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
index e3a43a47d78c51754ae01c46511b0ed56ddf2fc0..0fbd046e7c93653b0c862623e4716fdcfef39465 100644
--- a/include/drm/ttm/ttm_bo_driver.h
+++ b/include/drm/ttm/ttm_bo_driver.h
@@ -790,16 +790,7 @@ extern void ttm_mem_io_unlock(struct ttm_mem_type_manager *man);
* to make room for a buffer already reserved. (Buffers are reserved before
* they are evicted). The following algorithm prevents such deadlocks from
* occurring:
- * 1) Buffers are reserved with the lru spinlock held. Upon successful
- * reservation they are removed from the lru list. This stops a reserved buffer
- * from being evicted. However the lru spinlock is released between the time
- * a buffer is selected for eviction and the time it is reserved.
- * Therefore a check is made when a buffer is reserved for eviction, that it
- * is still the first buffer in the lru list, before it is removed from the
- * list. @check_lru == 1 forces this check. If it fails, the function returns
- * -EINVAL, and the caller should then choose a new buffer to evict and repeat
- * the procedure.
- * 2) Processes attempting to reserve multiple buffers other than for eviction,
+ * Processes attempting to reserve multiple buffers other than for eviction,
* (typically execbuf), should first obtain a unique 32-bit
* validation sequence number,
* and call this function with @use_sequence == 1 and @sequence == the unique
@@ -830,9 +821,39 @@ extern int ttm_bo_reserve(struct ttm_buffer_object *bo,
bool interruptible,
bool no_wait, bool use_sequence, uint32_t sequence);
+/**
+ * ttm_bo_reserve_slowpath_nolru:
+ * @bo: A pointer to a struct ttm_buffer_object.
+ * @interruptible: Sleep interruptible if waiting.
+ * @sequence: Set (@bo)->sequence to this value after lock
+ *
+ * This is called after ttm_bo_reserve returns -EAGAIN and we backed off
+ * from all our other reservations. Because there are no other reservations
+ * held by us, this function cannot deadlock any more.
+ *
+ * Will not remove reserved buffers from the lru lists.
+ * Otherwise identical to ttm_bo_reserve_slowpath.
+ */
+extern int ttm_bo_reserve_slowpath_nolru(struct ttm_buffer_object *bo,
+ bool interruptible,
+ uint32_t sequence);
+
/**
- * ttm_bo_reserve_locked:
+ * ttm_bo_reserve_slowpath:
+ * @bo: A pointer to a struct ttm_buffer_object.
+ * @interruptible: Sleep interruptible if waiting.
+ * @sequence: Set (@bo)->sequence to this value after lock
+ *
+ * This is called after ttm_bo_reserve returns -EAGAIN and we backed off
+ * from all our other reservations. Because there are no other reservations
+ * held by us, this function cannot deadlock any more.
+ */
+extern int ttm_bo_reserve_slowpath(struct ttm_buffer_object *bo,
+ bool interruptible, uint32_t sequence);
+
+/**
+ * ttm_bo_reserve_nolru:
*
* @bo: A pointer to a struct ttm_buffer_object.
* @interruptible: Sleep interruptible if waiting.
@@ -840,9 +861,7 @@ extern int ttm_bo_reserve(struct ttm_buffer_object *bo,
* @use_sequence: If @bo is already reserved, Only sleep waiting for
* it to become unreserved if @sequence < (@bo)->sequence.
*
- * Must be called with struct ttm_bo_global::lru_lock held,
- * and will not remove reserved buffers from the lru lists.
- * The function may release the LRU spinlock if it needs to sleep.
+ * Will not remove reserved buffers from the lru lists.
* Otherwise identical to ttm_bo_reserve.
*
* Returns:
@@ -855,7 +874,7 @@ extern int ttm_bo_reserve(struct ttm_buffer_object *bo,
* -EDEADLK: Bo already reserved using @sequence. This error code will only
* be returned if @use_sequence is set to true.
*/
-extern int ttm_bo_reserve_locked(struct ttm_buffer_object *bo,
+extern int ttm_bo_reserve_nolru(struct ttm_buffer_object *bo,
bool interruptible,
bool no_wait, bool use_sequence,
uint32_t sequence);
@@ -879,18 +898,6 @@ extern void ttm_bo_unreserve(struct ttm_buffer_object *bo);
*/
extern void ttm_bo_unreserve_locked(struct ttm_buffer_object *bo);
-/**
- * ttm_bo_wait_unreserved
- *
- * @bo: A pointer to a struct ttm_buffer_object.
- *
- * Wait for a struct ttm_buffer_object to become unreserved.
- * This is typically used in the execbuf code to relax cpu-usage when
- * a potential deadlock condition backoff.
- */
-extern int ttm_bo_wait_unreserved(struct ttm_buffer_object *bo,
- bool interruptible);
-
/*
* ttm_bo_util.c
*/