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drm/i915: Disallow preallocation of requests
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The intention was to allow the caller to avoid a failure to queue a
request having already written commands to the ring. However, this is a
moot point as the i915_add_request() can fail for other reasons than a
mere allocation failure and those failure cases are more likely than
ENOMEM. So the overlay code already had to handle i915_add_request()
failures, and due to

commit 3bb73ab
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Fri Jul 20 12:40:59 2012 +0100

    drm/i915: Allow late allocation of request for i915_add_request()

the error handling code in intel_overlay.c was subject to causing
double-frees, as found by coverity.

Rather than further complicate i915_add_request() and callers, realise
the battle is lost and adapt intel_overlay.c to take advantage of the
late allocation of requests.

v2: Handle callers passing in a NULL seqno.
v3: Ditto. This time for sure.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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Chris Wilson authored and Daniel Vetter committed Oct 12, 2012
1 parent 26b6e44 commit acb868d
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Showing 3 changed files with 24 additions and 65 deletions.
2 changes: 1 addition & 1 deletion drivers/gpu/drm/i915/i915_drv.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1427,7 +1427,7 @@ int __must_check i915_gpu_idle(struct drm_device *dev);
int __must_check i915_gem_idle(struct drm_device *dev);
int i915_add_request(struct intel_ring_buffer *ring,
struct drm_file *file,
struct drm_i915_gem_request *request);
u32 *seqno);
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);
Expand Down
15 changes: 8 additions & 7 deletions drivers/gpu/drm/i915/i915_gem.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1956,11 +1956,12 @@ i915_gem_next_request_seqno(struct intel_ring_buffer *ring)
int
i915_add_request(struct intel_ring_buffer *ring,
struct drm_file *file,
struct drm_i915_gem_request *request)
u32 *out_seqno)
{
drm_i915_private_t *dev_priv = ring->dev->dev_private;
uint32_t seqno;
struct drm_i915_gem_request *request;
u32 request_ring_position;
u32 seqno;
int was_empty;
int ret;

Expand All @@ -1975,11 +1976,9 @@ i915_add_request(struct intel_ring_buffer *ring,
if (ret)
return ret;

if (request == NULL) {
request = kmalloc(sizeof(*request), GFP_KERNEL);
if (request == NULL)
return -ENOMEM;
}
request = kmalloc(sizeof(*request), GFP_KERNEL);
if (request == NULL)
return -ENOMEM;

seqno = i915_gem_next_request_seqno(ring);

Expand Down Expand Up @@ -2031,6 +2030,8 @@ i915_add_request(struct intel_ring_buffer *ring,
}
}

if (out_seqno)
*out_seqno = seqno;
return 0;
}

Expand Down
72 changes: 15 additions & 57 deletions drivers/gpu/drm/i915/intel_overlay.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -210,7 +210,6 @@ static void intel_overlay_unmap_regs(struct intel_overlay *overlay,
}

static int intel_overlay_do_wait_request(struct intel_overlay *overlay,
struct drm_i915_gem_request *request,
void (*tail)(struct intel_overlay *))
{
struct drm_device *dev = overlay->dev;
Expand All @@ -219,12 +218,10 @@ static int intel_overlay_do_wait_request(struct intel_overlay *overlay,
int ret;

BUG_ON(overlay->last_flip_req);
ret = i915_add_request(ring, NULL, request);
if (ret) {
kfree(request);
return ret;
}
overlay->last_flip_req = request->seqno;
ret = i915_add_request(ring, NULL, &overlay->last_flip_req);
if (ret)
return ret;

overlay->flip_tail = tail;
ret = i915_wait_seqno(ring, overlay->last_flip_req);
if (ret)
Expand All @@ -241,35 +238,24 @@ static int intel_overlay_on(struct intel_overlay *overlay)
struct drm_device *dev = overlay->dev;
struct drm_i915_private *dev_priv = dev->dev_private;
struct intel_ring_buffer *ring = &dev_priv->ring[RCS];
struct drm_i915_gem_request *request;
int ret;

BUG_ON(overlay->active);
overlay->active = 1;

WARN_ON(IS_I830(dev) && !(dev_priv->quirks & QUIRK_PIPEA_FORCE));

request = kzalloc(sizeof(*request), GFP_KERNEL);
if (request == NULL) {
ret = -ENOMEM;
goto out;
}

ret = intel_ring_begin(ring, 4);
if (ret) {
kfree(request);
goto out;
}
if (ret)
return ret;

intel_ring_emit(ring, MI_OVERLAY_FLIP | MI_OVERLAY_ON);
intel_ring_emit(ring, overlay->flip_addr | OFC_UPDATE);
intel_ring_emit(ring, MI_WAIT_FOR_EVENT | MI_WAIT_FOR_OVERLAY_FLIP);
intel_ring_emit(ring, MI_NOOP);
intel_ring_advance(ring);

ret = intel_overlay_do_wait_request(overlay, request, NULL);
out:
return ret;
return intel_overlay_do_wait_request(overlay, NULL);
}

/* overlay needs to be enabled in OCMD reg */
Expand All @@ -279,17 +265,12 @@ static int intel_overlay_continue(struct intel_overlay *overlay,
struct drm_device *dev = overlay->dev;
drm_i915_private_t *dev_priv = dev->dev_private;
struct intel_ring_buffer *ring = &dev_priv->ring[RCS];
struct drm_i915_gem_request *request;
u32 flip_addr = overlay->flip_addr;
u32 tmp;
int ret;

BUG_ON(!overlay->active);

request = kzalloc(sizeof(*request), GFP_KERNEL);
if (request == NULL)
return -ENOMEM;

if (load_polyphase_filter)
flip_addr |= OFC_UPDATE;

Expand All @@ -299,22 +280,14 @@ static int intel_overlay_continue(struct intel_overlay *overlay,
DRM_DEBUG("overlay underrun, DOVSTA: %x\n", tmp);

ret = intel_ring_begin(ring, 2);
if (ret) {
kfree(request);
if (ret)
return ret;
}

intel_ring_emit(ring, MI_OVERLAY_FLIP | MI_OVERLAY_CONTINUE);
intel_ring_emit(ring, flip_addr);
intel_ring_advance(ring);

ret = i915_add_request(ring, NULL, request);
if (ret) {
kfree(request);
return ret;
}

overlay->last_flip_req = request->seqno;
return 0;
return i915_add_request(ring, NULL, &overlay->last_flip_req);
}

static void intel_overlay_release_old_vid_tail(struct intel_overlay *overlay)
Expand Down Expand Up @@ -350,26 +323,20 @@ static int intel_overlay_off(struct intel_overlay *overlay)
struct drm_i915_private *dev_priv = dev->dev_private;
struct intel_ring_buffer *ring = &dev_priv->ring[RCS];
u32 flip_addr = overlay->flip_addr;
struct drm_i915_gem_request *request;
int ret;

BUG_ON(!overlay->active);

request = kzalloc(sizeof(*request), GFP_KERNEL);
if (request == NULL)
return -ENOMEM;

/* According to intel docs the overlay hw may hang (when switching
* off) without loading the filter coeffs. It is however unclear whether
* this applies to the disabling of the overlay or to the switching off
* of the hw. Do it in both cases */
flip_addr |= OFC_UPDATE;

ret = intel_ring_begin(ring, 6);
if (ret) {
kfree(request);
if (ret)
return ret;
}

/* wait for overlay to go idle */
intel_ring_emit(ring, MI_OVERLAY_FLIP | MI_OVERLAY_CONTINUE);
intel_ring_emit(ring, flip_addr);
Expand All @@ -380,8 +347,7 @@ static int intel_overlay_off(struct intel_overlay *overlay)
intel_ring_emit(ring, MI_WAIT_FOR_EVENT | MI_WAIT_FOR_OVERLAY_FLIP);
intel_ring_advance(ring);

return intel_overlay_do_wait_request(overlay, request,
intel_overlay_off_tail);
return intel_overlay_do_wait_request(overlay, intel_overlay_off_tail);
}

/* recover from an interruption due to a signal
Expand Down Expand Up @@ -426,24 +392,16 @@ static int intel_overlay_release_old_vid(struct intel_overlay *overlay)
return 0;

if (I915_READ(ISR) & I915_OVERLAY_PLANE_FLIP_PENDING_INTERRUPT) {
struct drm_i915_gem_request *request;

/* synchronous slowpath */
request = kzalloc(sizeof(*request), GFP_KERNEL);
if (request == NULL)
return -ENOMEM;

ret = intel_ring_begin(ring, 2);
if (ret) {
kfree(request);
if (ret)
return ret;
}

intel_ring_emit(ring, MI_WAIT_FOR_EVENT | MI_WAIT_FOR_OVERLAY_FLIP);
intel_ring_emit(ring, MI_NOOP);
intel_ring_advance(ring);

ret = intel_overlay_do_wait_request(overlay, request,
ret = intel_overlay_do_wait_request(overlay,
intel_overlay_release_old_vid_tail);
if (ret)
return ret;
Expand Down

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