drm/ttm: convert to the reservation api
Now that the code is compatible in semantics, flip the switch.
Use ww_mutex instead of the homegrown implementation.
ww_mutex uses -EDEADLK to signal that the caller has to back off,
and -EALREADY to indicate this buffer is already held by the caller.
ttm used -EAGAIN and -EDEADLK for those, respectively. So some changes
were needed to handle this correctly.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index b912375..5f9fe80 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -150,6 +150,9 @@
if (bo->ttm)
ttm_tt_destroy(bo->ttm);
atomic_dec(&bo->glob->bo_count);
+ if (bo->resv == &bo->ttm_resv)
+ reservation_object_fini(&bo->ttm_resv);
+
if (bo->destroy)
bo->destroy(bo);
else {
@@ -158,18 +161,6 @@
ttm_mem_global_free(bdev->glob->mem_glob, acc_size);
}
-static int ttm_bo_wait_unreserved(struct ttm_buffer_object *bo,
- bool interruptible)
-{
- if (interruptible) {
- return wait_event_interruptible(bo->event_queue,
- !ttm_bo_is_reserved(bo));
- } else {
- wait_event(bo->event_queue, !ttm_bo_is_reserved(bo));
- return 0;
- }
-}
-
void ttm_bo_add_to_lru(struct ttm_buffer_object *bo)
{
struct ttm_bo_device *bdev = bo->bdev;
@@ -218,65 +209,27 @@
bool no_wait, bool use_ticket,
struct ww_acquire_ctx *ticket)
{
- int ret;
+ int ret = 0;
- while (unlikely(atomic_xchg(&bo->reserved, 1) != 0)) {
- /**
- * Deadlock avoidance for multi-bo reserving.
- */
- if (use_ticket && bo->seq_valid) {
- /**
- * We've already reserved this one.
- */
- if (unlikely(ticket->stamp == bo->val_seq))
- return -EDEADLK;
- /**
- * Already reserved by a thread that will not back
- * off for us. We need to back off.
- */
- if (unlikely(ticket->stamp - bo->val_seq <= LONG_MAX))
- return -EAGAIN;
- }
+ if (no_wait) {
+ bool success;
- if (no_wait)
+ /* not valid any more, fix your locking! */
+ if (WARN_ON(ticket))
return -EBUSY;
- ret = ttm_bo_wait_unreserved(bo, interruptible);
-
- if (unlikely(ret))
- return ret;
+ success = ww_mutex_trylock(&bo->resv->lock);
+ return success ? 0 : -EBUSY;
}
- if (use_ticket) {
- 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 - ticket->stamp <= LONG_MAX)
- || !bo->seq_valid))
- 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 = ticket->stamp;
- bo->seq_valid = true;
- if (wake_up)
- wake_up_all(&bo->event_queue);
- } else {
- bo->seq_valid = false;
- }
-
- return 0;
+ if (interruptible)
+ ret = ww_mutex_lock_interruptible(&bo->resv->lock,
+ ticket);
+ else
+ ret = ww_mutex_lock(&bo->resv->lock, ticket);
+ if (ret == -EINTR)
+ return -ERESTARTSYS;
+ return ret;
}
EXPORT_SYMBOL(ttm_bo_reserve);
@@ -313,50 +266,27 @@
return ret;
}
-int ttm_bo_reserve_slowpath_nolru(struct ttm_buffer_object *bo,
- bool interruptible,
- struct ww_acquire_ctx *ticket)
-{
- bool wake_up = false;
- int ret;
-
- while (unlikely(atomic_xchg(&bo->reserved, 1) != 0)) {
- WARN_ON(bo->seq_valid && ticket->stamp == bo->val_seq);
-
- ret = ttm_bo_wait_unreserved(bo, interruptible);
-
- if (unlikely(ret))
- return ret;
- }
-
- if (bo->val_seq - ticket->stamp < LONG_MAX || !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 = ticket->stamp;
- 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, struct ww_acquire_ctx *ticket)
{
struct ttm_bo_global *glob = bo->glob;
- int put_count, ret;
+ int put_count = 0;
+ int ret = 0;
- ret = ttm_bo_reserve_slowpath_nolru(bo, interruptible, ticket);
- if (likely(!ret)) {
+ if (interruptible)
+ ret = ww_mutex_lock_slow_interruptible(&bo->resv->lock,
+ ticket);
+ else
+ ww_mutex_lock_slow(&bo->resv->lock, ticket);
+
+ 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);
- }
+ } else if (ret == -EINTR)
+ ret = -ERESTARTSYS;
+
return ret;
}
EXPORT_SYMBOL(ttm_bo_reserve_slowpath);
@@ -364,8 +294,7 @@
void ttm_bo_unreserve_ticket_locked(struct ttm_buffer_object *bo, struct ww_acquire_ctx *ticket)
{
ttm_bo_add_to_lru(bo);
- atomic_set(&bo->reserved, 0);
- wake_up_all(&bo->event_queue);
+ ww_mutex_unlock(&bo->resv->lock);
}
void ttm_bo_unreserve(struct ttm_buffer_object *bo)
@@ -558,17 +487,7 @@
}
ttm_bo_mem_put(bo, &bo->mem);
- atomic_set(&bo->reserved, 0);
- wake_up_all(&bo->event_queue);
-
- /*
- * Since the final reference to this bo may not be dropped by
- * the current task we have to put a memory barrier here to make
- * sure the changes done in this function are always visible.
- *
- * This function only needs protection against the final kref_put.
- */
- smp_mb__before_atomic_dec();
+ ww_mutex_unlock (&bo->resv->lock);
}
static void ttm_bo_cleanup_refs_or_queue(struct ttm_buffer_object *bo)
@@ -600,10 +519,8 @@
sync_obj = driver->sync_obj_ref(bo->sync_obj);
spin_unlock(&bdev->fence_lock);
- if (!ret) {
- atomic_set(&bo->reserved, 0);
- wake_up_all(&bo->event_queue);
- }
+ if (!ret)
+ ww_mutex_unlock(&bo->resv->lock);
kref_get(&bo->list_kref);
list_add_tail(&bo->ddestroy, &bdev->ddestroy);
@@ -653,8 +570,7 @@
sync_obj = driver->sync_obj_ref(bo->sync_obj);
spin_unlock(&bdev->fence_lock);
- atomic_set(&bo->reserved, 0);
- wake_up_all(&bo->event_queue);
+ ww_mutex_unlock(&bo->resv->lock);
spin_unlock(&glob->lru_lock);
ret = driver->sync_obj_wait(sync_obj, false, interruptible);
@@ -692,8 +608,7 @@
spin_unlock(&bdev->fence_lock);
if (ret || unlikely(list_empty(&bo->ddestroy))) {
- atomic_set(&bo->reserved, 0);
- wake_up_all(&bo->event_queue);
+ ww_mutex_unlock(&bo->resv->lock);
spin_unlock(&glob->lru_lock);
return ret;
}
@@ -1253,6 +1168,7 @@
int ret = 0;
unsigned long num_pages;
struct ttm_mem_global *mem_glob = bdev->glob->mem_glob;
+ bool locked;
ret = ttm_mem_global_alloc(mem_glob, acc_size, false, false);
if (ret) {
@@ -1279,8 +1195,6 @@
kref_init(&bo->kref);
kref_init(&bo->list_kref);
atomic_set(&bo->cpu_writers, 0);
- atomic_set(&bo->reserved, 1);
- init_waitqueue_head(&bo->event_queue);
INIT_LIST_HEAD(&bo->lru);
INIT_LIST_HEAD(&bo->ddestroy);
INIT_LIST_HEAD(&bo->swap);
@@ -1298,37 +1212,34 @@
bo->mem.bus.io_reserved_count = 0;
bo->priv_flags = 0;
bo->mem.placement = (TTM_PL_FLAG_SYSTEM | TTM_PL_FLAG_CACHED);
- bo->seq_valid = false;
bo->persistent_swap_storage = persistent_swap_storage;
bo->acc_size = acc_size;
bo->sg = sg;
+ bo->resv = &bo->ttm_resv;
+ reservation_object_init(bo->resv);
atomic_inc(&bo->glob->bo_count);
ret = ttm_bo_check_placement(bo, placement);
- if (unlikely(ret != 0))
- goto out_err;
/*
* For ttm_bo_type_device buffers, allocate
* address space from the device.
*/
- if (bo->type == ttm_bo_type_device ||
- bo->type == ttm_bo_type_sg) {
+ if (likely(!ret) &&
+ (bo->type == ttm_bo_type_device ||
+ bo->type == ttm_bo_type_sg))
ret = ttm_bo_setup_vm(bo);
- if (ret)
- goto out_err;
- }
- ret = ttm_bo_validate(bo, placement, interruptible, false);
- if (ret)
- goto out_err;
+ locked = ww_mutex_trylock(&bo->resv->lock);
+ WARN_ON(!locked);
+
+ if (likely(!ret))
+ ret = ttm_bo_validate(bo, placement, interruptible, false);
ttm_bo_unreserve(bo);
- return 0;
-out_err:
- ttm_bo_unreserve(bo);
- ttm_bo_unref(&bo);
+ if (unlikely(ret))
+ ttm_bo_unref(&bo);
return ret;
}
@@ -1941,8 +1852,7 @@
* already swapped buffer.
*/
- atomic_set(&bo->reserved, 0);
- wake_up_all(&bo->event_queue);
+ ww_mutex_unlock(&bo->resv->lock);
kref_put(&bo->list_kref, ttm_bo_release_list);
return ret;
}