From: Daniel Vetter Date: Fri, 19 Feb 2010 10:51:58 +0000 (+0100) Subject: drm/i915: extract fence stealing code X-Git-Tag: v2.6.34-rc4~12^2~68^2~6 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=ae3db24aab398fb5f985696c12362eb12ef65812;p=platform%2Fkernel%2Flinux-3.10.git drm/i915: extract fence stealing code 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 Reviewed-by: Chris Wilson Signed-off-by: Eric Anholt --- diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index e6b85cd..ce1c026 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -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; - - 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; - } + ret = i915_find_fence_reg(dev); + 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; }