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drm/ttm: remove lru_lock around ttm_bo_reserve

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There should no longer be assumptions that reserve will always succeed
with the lru lock held, so we can safely break the whole atomic
reserve/lru thing. As a bonus this fixes most lockdep annotations for
reservations.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
This commit is contained in:
Maarten Lankhorst
2013-01-15 14:56:37 +01:00
parent 979ee290ff
commit 63d0a41955
3 changed files with 40 additions and 35 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/gpu/drm/ttm/ttm_bo.c
+35 -19
View File
@@ -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;
}
@@ -289,14 +298,14 @@ 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);
ttm_bo_list_ref_sub(bo, put_count, true);
spin_unlock(&glob->lru_lock);
ttm_bo_list_ref_sub(bo, put_count, true);
}
return ret;
}
@@ -510,7 +519,7 @@ 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);
@@ -603,7 +612,7 @@ 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,
@@ -667,7 +676,14 @@ 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);
@@ -815,7 +831,7 @@ 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;
}
@@ -1796,7 +1812,7 @@ 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;
}
drivers/gpu/drm/ttm/ttm_execbuf_util.c
+1 -1
View File
@@ -153,7 +153,7 @@ retry:
struct ttm_buffer_object *bo = entry->bo;
retry_this_bo:
ret = ttm_bo_reserve_locked(bo, true, true, true, val_seq);
ret = ttm_bo_reserve_nolru(bo, true, true, true, val_seq);
switch (ret) {
case 0:
break;