On Mon, 2016-01-11 at 21:29 +0000, Chris Wilson wrote:
> On Mon, Jan 11, 2016 at 05:15:54PM +0000, Tvrtko Ursulin wrote:
> > > Is that not what was written? I take it my telepathy isn't working
> > > again.
> >
> > Sorry not a new loop, new case in a old loop. This is the hunk I think
> > is not helping readability:
> >
> > @@ -869,11 +967,29 @@ i915_gem_gtt_pwrite_fast(struct drm_i915_private
> > *i915,
> > /* If we get a fault while copying data, then (presumably) our
> > * source page isn't available. Return the error and we'll
> > * retry in the slow path.
> > + * If the object is non-shmem backed, we retry again with the
> > + * path that handles page fault.
> > */
> > - if (fast_user_write(i915->gtt.mappable, page_base,
> > - page_offset, user_data, page_length)) {
> > - ret = -EFAULT;
> > - goto out_flush;
> > + if (faulted || fast_user_write(i915->gtt.mappable,
> > + page_base, page_offset,
> > + user_data, page_length)) {
> > + if (!obj->base.filp) {
>
> This is just wrong, we neither need the faulted nor the difference in
> behaviour based on storage.
> -Chris
>
Yes, this will not be required, I see. As we are planning to provide a
partial fallback for all objs (shmem backed as well as non-shmem
backed).
So to conclude, a partial fallback (slow_user_access()) for all objs if
fast_user_write() fails.
And a full fallback (shmem_pwrite()) for only shmem backed objects if
slow_user_access() fails as well.
...
hit_by_slowpath = 1;
mutex_unlock(&dev->struct_mutex);
if (slow_user_access(i915->gtt.mappable,
page_base,
page_offset, user_data,
page_length, true)) {
ret = -EFAULT;
mutex_lock(&dev->struct_mutex);
goto out_flush;
}
mutex_lock(&dev->struct_mutex);
...
Thanks,
-Ankit
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