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add destroy listener for textures #1962

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@Emantor Emantor commented Dec 22, 2019

Add a destroy listener for textures, which destroys the gles2 textures
when the renderer is destroyed.

Fixes #1949


I am not entirely sure about the API changes, since the wlr_renderer is now passed directly to the texture creation functions. I am all ears for possible improvements.

@Emantor Emantor force-pushed the topic/texture_destroy_listener branch from 62023ab to f6e6029 Compare December 22, 2019 15:07
@ddevault ddevault added the breaking Breaking change in public API label Dec 23, 2019
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The intent with the current API was to allow compositors to create wlr_textures without having to use wlr_renderer. However it doesn't seem like this is used by anyone (@ammen99?), since wlr_surface requires wlr_renderer anyway.

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See #775

An alternative would be to add a destroy signal to wlr_egl.

@Emantor Emantor force-pushed the topic/texture_destroy_listener branch from f6e6029 to 197e5b5 Compare December 29, 2019 11:56
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Emantor commented Dec 29, 2019

Pushed a new version which moves the destruction function to wlr_texture instead of being gles2 specific. I can also separate out the gles2 texture creation function into its own commit if required.

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This is still GLES2 specific, as the renderer passed to the texture creation functions take a wlr_renderer which is asserted to be the GLES2 renderer.

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Emantor commented Dec 29, 2019

Yes, since there is no other renderer. But the listener is now registered for all wlr_textures in the init function. The texture creation functions obv. need to assert since they are gles2 specific. Only the texture destruction part on renderer destroy should now work for all wlr_texture parts, if we had more than gles2.

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ammen99 commented Dec 29, 2019

However it doesn't seem like this is used by anyone (@ammen99?), since wlr_surface requires wlr_renderer anyway.

I am not using any of the functions which are touched here, so I am not against this change. Renderers are supposed to be redesigned sometime in the future anyway IIRC.

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emersion commented Jan 5, 2020

Maybe we should just hide these functions from the public API for now.

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Emantor commented Feb 20, 2020

Maybe we should just hide these functions from the public API for now.

Should this be done in this PR? Is there anything else blocking this PR?

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Yeah, since this PR contains breaking changes, can we make these functions private?

@Emantor Emantor force-pushed the topic/texture_destroy_listener branch from 197e5b5 to d656a7c Compare February 22, 2020 13:33
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Emantor commented Feb 22, 2020

Done, I also cleaned up some gles2.h imports.

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Are wlr_texture users prepared for the texture to be implicitly destroyed?

include/render/gles2.h Outdated Show resolved Hide resolved
@Emantor Emantor force-pushed the topic/texture_destroy_listener branch from 7a155c7 to 5c82e0d Compare March 2, 2020 13:00
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Emantor commented Mar 2, 2020

Are wlr_texture users prepared for the texture to be implicitly destroyed?

Not sure how to verify this short of verifying all callers, I have been running this PR on top of master with address sanitizer and tested output hotplug so far.

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emersion commented Mar 2, 2020

Grepping for wlr_texture:

  • backend/drm/renderer.c: since the backend has ownership over the renderer it should be fine
  • types/wlr_output.c: used for cursors, would be safer to add a listener
  • types/wlr_buffer.c: should add a listener

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Emantor commented Mar 4, 2020

Grepping for wlr_texture:

* `backend/drm/renderer.c`: since the backend has ownership over the renderer it should be fine

* `types/wlr_output.c`: used for cursors, would be safer to add a listener

Looks straightforward.

* `types/wlr_buffer.c`: should add a listener

Hm, how do I handle the reference counting? Just ignore, send a release for the buffer and subsequently destroy?

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Hm, how do I handle the reference counting? Just ignore, send a release for the buffer and subsequently destroy?

We shouldn't release the buffer. We could set texture to NULL instead (this would be a breaking change I think? However most callers should already be prepared for it via wlr_surface_get_texture).

Emantor added 5 commits April 18, 2020 13:14
Add a destroy listener for textures, which destroys the textures of a
renderer upon renderer destruction.

Fixes swaywm#1949
Remove unnecessary imports and if necessary replace with the correct
ones.
Remove the prefix, move the functions and remove the wrappers inside the
renderer.
In case the renderer is destroyed, it will implicitly destroy the
textures. Set buffer->texture to NULL to prevent use after free and
guard against a NULL texture in wlr_client_buffer_apply_damage.
Listen for a renderer destory event and remove the reference to the to
be destroyed texture from the cursor.
@Emantor Emantor force-pushed the topic/texture_destroy_listener branch from 5c82e0d to c3773c0 Compare April 18, 2020 11:15
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Emantor commented Apr 18, 2020

This should be ready for review.

@@ -18,6 +18,8 @@ struct wlr_texture_impl;

struct wlr_texture {
const struct wlr_texture_impl *impl;

struct wl_listener renderer_destroy;
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This listener may run before or after other renderer destroy listeners (listener call order is undefined). This can cause a use-after-free if the texture listener is called first, then the buffer/output listener is called.

We should probably add a destroy signal to wlr_texture to prevent this.

emersion added a commit to emersion/wlroots that referenced this pull request Jul 28, 2020
These functions are unused by compositors (see e.g. [1]) and prevent
wlr_gles2_texture from accessing wlr_gles2_renderer state. This is an
issue for proper teardown [2] and for accessing GLES2 extensions.

[1]: swaywm#1962 (comment)
[2]: swaywm#1962
ddevault pushed a commit that referenced this pull request Jul 28, 2020
These functions are unused by compositors (see e.g. [1]) and prevent
wlr_gles2_texture from accessing wlr_gles2_renderer state. This is an
issue for proper teardown [2] and for accessing GLES2 extensions.

[1]: #1962 (comment)
[2]: #1962
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Emantor commented Dec 4, 2020

Will be superseded by usage of wlr_buffer

@Emantor Emantor closed this Dec 4, 2020
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emersion commented Dec 4, 2020

Hm, I don't think so. wlr_texture will remain as the abstraction for pixels ready to be textured from by the renderer.

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Emantor commented Dec 4, 2020

Hm, I don't think so. wlr_texture will remain as the abstraction for pixels ready to be textured from by the renderer.

Yep, but I remember the last place where this was lacking to be the cursor code having no nice place to hook into. And with your reworks in flight currently (and this PR not having been rebased in a while), I'll see how things turn out in master. I intend to pick this up again, but it will be a while, so closing this for now.

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emersion commented Dec 4, 2020

I see! No problem, thanks for working on this :)

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Use-after-free when destroying textures after renderer
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