Re: [PATCH 1/6] drm/i915: Allow late allocation of request for i915_add_request()

Daniel Vetter
2012-07-12T17:43:47Z

On Thu, Jul 12, 2012 at 04:13:34PM +0100, Chris Wilson wrote:
> Request preallocation was added to i915_add_request() in order to
> support the overlay. However, not all uses care and can quite happily
> ignore the failure to allocate the request as they will simply repeat
> the request in the future.
>
> By pushing the allocation down into i915_add_request(), we can then
> remove some rather ugly error handling in the callers.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
> drivers/gpu/drm/i915/i915_drv.h | 6 ++---
> drivers/gpu/drm/i915/i915_gem.c | 39 ++++++++++------------------
> drivers/gpu/drm/i915/i915_gem_execbuffer.c | 7 +----
> 3 files changed, 17 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 627fe35..51e234e 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1358,9 +1358,9 @@ void i915_gem_init_ppgtt(struct drm_device *dev);
> void i915_gem_cleanup_ringbuffer(struct drm_device *dev);
> int __must_check i915_gpu_idle(struct drm_device *dev);
> int __must_check i915_gem_idle(struct drm_device *dev);
> -int __must_check i915_add_request(struct intel_ring_buffer *ring,
> - struct drm_file *file,
> - struct drm_i915_gem_request *request);
> +int i915_add_request(struct intel_ring_buffer *ring,
> + struct drm_file *file,
> + struct drm_i915_gem_request *request);
> int __must_check i915_wait_seqno(struct intel_ring_buffer *ring,
> uint32_t seqno);
> int i915_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf);
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 53c3946..875b745 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -1597,7 +1597,6 @@ i915_add_request(struct intel_ring_buffer *ring,
> ring->gpu_caches_dirty = false;
> }
>
> - BUG_ON(request == NULL);
> seqno = i915_gem_next_request_seqno(ring);
>
> /* Record the position of the start of the request so that
> @@ -1609,7 +1608,13 @@ i915_add_request(struct intel_ring_buffer *ring,
>
> ret = ring->add_request(ring, &seqno);
> if (ret)
> - return ret;
> + return ret;
> +
> + if (request == NULL) {
> + request = kmalloc(sizeof(*request), GFP_KERNEL);
> + if (request == NULL)
> + return -ENOMEM;
> + }

Hm, shouldn't we try to allocate the request struct before we emit the
request? Otherwise looks good.
-Daniel
>
> trace_i915_gem_request_add(ring, seqno);
>
> @@ -1859,14 +1864,8 @@ i915_gem_retire_work_handler(struct work_struct *work)
> */
> idle = true;
> for_each_ring(ring, dev_priv, i) {
> - if (ring->gpu_caches_dirty) {
> - struct drm_i915_gem_request *request;
> -
> - request = kzalloc(sizeof(*request), GFP_KERNEL);
> - if (request == NULL ||
> - i915_add_request(ring, NULL, request))
> - kfree(request);
> - }
> + if (ring->gpu_caches_dirty)
> + i915_add_request(ring, NULL, NULL);
>
> idle &= list_empty(&ring->request_list);
> }
> @@ -1913,25 +1912,13 @@ i915_gem_check_wedge(struct drm_i915_private *dev_priv,
> static int
> i915_gem_check_olr(struct intel_ring_buffer *ring, u32 seqno)
> {
> - int ret = 0;
> + int ret;
>
> BUG_ON(!mutex_is_locked(&ring->dev->struct_mutex));
>
> - if (seqno == ring->outstanding_lazy_request) {
> - struct drm_i915_gem_request *request;
> -
> - request = kzalloc(sizeof(*request), GFP_KERNEL);
> - if (request == NULL)
> - return -ENOMEM;
> -
> - ret = i915_add_request(ring, NULL, request);
> - if (ret) {
> - kfree(request);
> - return ret;
> - }
> -
> - BUG_ON(seqno != request->seqno);
> - }
> + ret = 0;
> + if (seqno == ring->outstanding_lazy_request)
> + ret = i915_add_request(ring, NULL, NULL);
>
> return ret;
> }
> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> index 88e2e11..0c26692 100644
> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> @@ -967,16 +967,11 @@ i915_gem_execbuffer_retire_commands(struct drm_device *dev,
> struct drm_file *file,
> struct intel_ring_buffer *ring)
> {
> - struct drm_i915_gem_request *request;
> -
> /* Unconditionally force add_request to emit a full flush. */
> ring->gpu_caches_dirty = true;
>
> /* Add a breadcrumb for the completion of the batch buffer */
> - request = kzalloc(sizeof(*request), GFP_KERNEL);
> - if (request == NULL || i915_add_request(ring, file, request)) {
> - kfree(request);
> - }
> + (void)i915_add_request(ring, file, NULL);
> }
>
> static int
> --
> 1.7.10.4
>
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--
Daniel Vetter
Mail: daniel@ffwll.ch
Mobile: +41 (0)79 365 57 48