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drm/i915: extract fence stealing code

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The spaghetti logic in there tripped up my brain's code parser for a
few secs. Prevent this from happening again by extracting the fence
stealing code into a seperate functions. IMHO this slightly clears up
the code flow.

v2: Beautified according to ickle's comments.
v3: ickle forgot to flush his comment queue ... Now there's also a
we-are-paranoid BUG_ON in there.
v4: I've forgotten to switch on my brain when doing v3. Now the BUG_ON
actually checks something useful.
v5: Clean up a stale comment as noted by Eric Anholt.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Eric Anholt <eric@anholt.net>
This commit is contained in:
Daniel Vetter 2010-02-19 11:51:58 +01:00 committed by Eric Anholt
parent 4a87b8ca21
commit ae3db24aab
1 changed files with 60 additions and 47 deletions
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107
drivers/gpu/drm/i915/i915_gem.c
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@ -2382,6 +2382,58 @@ static void i830_write_fence_reg(struct drm_i915_fence_reg *reg)
I915_WRITE(FENCE_REG_830_0 + (regnum * 4), val);
}
static int i915_find_fence_reg(struct drm_device *dev)
{
struct drm_i915_fence_reg *reg = NULL;
struct drm_i915_gem_object *obj_priv = NULL;
struct drm_i915_private *dev_priv = dev->dev_private;
struct drm_gem_object *obj = NULL;
int i, avail, ret;
/* First try to find a free reg */
avail = 0;
for (i = dev_priv->fence_reg_start; i < dev_priv->num_fence_regs; i++) {
reg = &dev_priv->fence_regs[i];
if (!reg->obj)
return i;
obj_priv = reg->obj->driver_private;
if (!obj_priv->pin_count)
avail++;
}
if (avail == 0)
return -ENOSPC;
/* None available, try to steal one or wait for a user to finish */
i = I915_FENCE_REG_NONE;
list_for_each_entry(obj_priv, &dev_priv->mm.fence_list,
fence_list) {
obj = obj_priv->obj;
if (obj_priv->pin_count)
continue;
/* found one! */
i = obj_priv->fence_reg;
break;
}
BUG_ON(i == I915_FENCE_REG_NONE);
/* We only have a reference on obj from the active list. put_fence_reg
* might drop that one, causing a use-after-free in it. So hold a
* private reference to obj like the other callers of put_fence_reg
* (set_tiling ioctl) do. */
drm_gem_object_reference(obj);
ret = i915_gem_object_put_fence_reg(obj);
drm_gem_object_unreference(obj);
if (ret != 0)
return ret;
return i;
}
/**
* i915_gem_object_get_fence_reg - set up a fence reg for an object
* @obj: object to map through a fence reg
@ -2402,8 +2454,7 @@ i915_gem_object_get_fence_reg(struct drm_gem_object *obj)
struct drm_i915_private *dev_priv = dev->dev_private;
struct drm_i915_gem_object *obj_priv = obj->driver_private;
struct drm_i915_fence_reg *reg = NULL;
struct drm_i915_gem_object *old_obj_priv = NULL;
int i, ret, avail;
int ret;
/* Just update our place in the LRU if our fence is getting used. */
if (obj_priv->fence_reg != I915_FENCE_REG_NONE) {
@ -2431,51 +2482,12 @@ i915_gem_object_get_fence_reg(struct drm_gem_object *obj)
break;
}
/* First try to find a free reg */
avail = 0;
for (i = dev_priv->fence_reg_start; i < dev_priv->num_fence_regs; i++) {
reg = &dev_priv->fence_regs[i];
if (!reg->obj)
break;
ret = i915_find_fence_reg(dev);
if (ret < 0)
return ret;
old_obj_priv = reg->obj->driver_private;
if (!old_obj_priv->pin_count)
avail++;
}
/* None available, try to steal one or wait for a user to finish */
if (i == dev_priv->num_fence_regs) {
struct drm_gem_object *old_obj = NULL;
if (avail == 0)
return -ENOSPC;
list_for_each_entry(old_obj_priv, &dev_priv->mm.fence_list,
fence_list) {
old_obj = old_obj_priv->obj;
if (old_obj_priv->pin_count)
continue;
/* Take a reference, as otherwise the wait_rendering
* below may cause the object to get freed out from
* under us.
*/
drm_gem_object_reference(old_obj);
break;
}
i = old_obj_priv->fence_reg;
reg = &dev_priv->fence_regs[i];
ret = i915_gem_object_put_fence_reg(old_obj);
drm_gem_object_unreference(old_obj);
if (ret != 0)
return ret;
}
obj_priv->fence_reg = i;
obj_priv->fence_reg = ret;
reg = &dev_priv->fence_regs[obj_priv->fence_reg];
list_add_tail(&obj_priv->fence_list, &dev_priv->mm.fence_list);
reg->obj = obj;
@ -2489,7 +2501,8 @@ i915_gem_object_get_fence_reg(struct drm_gem_object *obj)
else
i830_write_fence_reg(reg);
trace_i915_gem_object_get_fence(obj, i, obj_priv->tiling_mode);
trace_i915_gem_object_get_fence(obj, obj_priv->fence_reg,
obj_priv->tiling_mode);
return 0;
}