diff options
author | Dave Airlie <airlied@redhat.com> | 2013-02-08 14:02:32 +1000 |
---|---|---|
committer | Dave Airlie <airlied@redhat.com> | 2013-02-08 14:02:32 +1000 |
commit | b9e5071386007729110e86fd2c55c687085624e3 (patch) | |
tree | 4720ecd2ee9be3f8c46e71d75119219db1692507 | |
parent | 85a7ce67f3ebfd5975ffd1febcabfe4999ca911d (diff) | |
parent | cc4c0c4de3c775be22072ec3251f2e581b63d9a0 (diff) | |
download | linux-b9e5071386007729110e86fd2c55c687085624e3.tar.bz2 |
Merge branch 'for-airlied' of git://people.freedesktop.org/~mlankhorst/linux into drm-next
TTM reservations changes, preparing for new reservation mutex system.
* 'for-airlied' of git://people.freedesktop.org/~mlankhorst/linux:
drm/ttm: unexport ttm_bo_wait_unreserved
drm/nouveau: use ttm_bo_reserve_slowpath in validate_init, v2
drm/ttm: use ttm_bo_reserve_slowpath_nolru in ttm_eu_reserve_buffers, v2
drm/ttm: add ttm_bo_reserve_slowpath
drm/ttm: cleanup ttm_eu_reserve_buffers handling
drm/ttm: remove lru_lock around ttm_bo_reserve
drm/nouveau: increase reservation sequence every retry
drm/vmwgfx: always use ttm_bo_is_reserved
-rw-r--r-- | drivers/gpu/drm/nouveau/nouveau_gem.c | 20 | ||||
-rw-r--r-- | drivers/gpu/drm/ttm/ttm_bo.c | 103 | ||||
-rw-r--r-- | drivers/gpu/drm/ttm/ttm_execbuf_util.c | 78 | ||||
-rw-r--r-- | drivers/gpu/drm/vmwgfx/vmwgfx_resource.c | 4 | ||||
-rw-r--r-- | include/drm/ttm/ttm_bo_driver.h | 61 |
5 files changed, 178 insertions, 88 deletions
diff --git a/drivers/gpu/drm/nouveau/nouveau_gem.c b/drivers/gpu/drm/nouveau/nouveau_gem.c index 24e0aabda03c..d98bee012cab 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 @@ retry: 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 @@ retry: 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 @@ retry: 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 52b20b12c83a..9b07b7d44a58 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 cd9e4523dc56..7b90def15674 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 @@ retry_this_bo: 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 e01a17b407b2..16556170fb32 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 e3a43a47d78c..0fbd046e7c93 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 */ |