On Fri, Oct 07, 2016 at 05:10:04PM +0100, Tvrtko Ursulin wrote:
>
> On 07/10/2016 10:46, Chris Wilson wrote:
> >In forthcoming patches, we want to be able to dynamically allocate the
> >wait_queue_t used whilst awaiting. This is more convenient if we extend
> >the i915_sw_fence_await_sw_fence() to perform the allocation for us if
> >we pass in a gfp mask as an alternative than a preallocated struct.
> >
> >Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> >Reviewed-by: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> >---
> > drivers/gpu/drm/i915/i915_sw_fence.c | 40 ++++++++++++++++++++++++++++++++----
> > drivers/gpu/drm/i915/i915_sw_fence.h | 8 ++++++++
> > 2 files changed, 44 insertions(+), 4 deletions(-)
> >
> >diff --git a/drivers/gpu/drm/i915/i915_sw_fence.c b/drivers/gpu/drm/i915/i915_sw_fence.c
> >index 1e5cbc585ca2..dfb59dced0ce 100644
> >--- a/drivers/gpu/drm/i915/i915_sw_fence.c
> >+++ b/drivers/gpu/drm/i915/i915_sw_fence.c
> >@@ -13,6 +13,8 @@
> > #include "i915_sw_fence.h"
> >+#define I915_SW_FENCE_FLAG_ALLOC BIT(0)
> >+
>
> You collide with WQ_FLAG_EXCLUSIVE here, so I assume i915 will have
> complete control of the wq in question?
Hmm, we should move bit as well, but yes the flag is atm private to the
wake up function for which we use a custom function.
> >+ wq = kmalloc(sizeof(*wq), gfp);
> >+ if (!wq) {
> >+ if (!gfpflags_allow_blocking(gfp))
> >+ return -ENOMEM;
> >+
> >+ i915_sw_fence_wait(signaler);
>
> This looks like a strange API, unless I am missing something - it
> normally sets things up for waiting, unless the allocation fails
> when it actually does the wait?
Yes. If we blocked on the malloc and failed, we block a little more for
the completion. iirc, the idea came from the async task.
>
> >+ return 0;
> >+ }
> >+
> >+ pending |= I915_SW_FENCE_FLAG_ALLOC;
>
> Why is this stored in pending? Just because it is around as re-used?
Urm, yes. s/pending/tmp/
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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