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authorDave Airlie <airlied@redhat.com>2013-02-08 14:02:32 +1000
committerDave Airlie <airlied@redhat.com>2013-02-08 14:02:32 +1000
commitb9e5071386007729110e86fd2c55c687085624e3 (patch)
tree4720ecd2ee9be3f8c46e71d75119219db1692507 /drivers/gpu/drm/ttm
parent85a7ce67f3ebfd5975ffd1febcabfe4999ca911d (diff)
parentcc4c0c4de3c775be22072ec3251f2e581b63d9a0 (diff)
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
Diffstat (limited to 'drivers/gpu/drm/ttm')
-rw-r--r--drivers/gpu/drm/ttm/ttm_bo.c103
-rw-r--r--drivers/gpu/drm/ttm/ttm_execbuf_util.c78
2 files changed, 126 insertions, 55 deletions
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 52b20b12c83..9b07b7d44a5 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 cd9e4523dc5..7b90def1567 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);