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mesa: fix Blender crash due to optimizations in buffer reference counting

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The problem was that I assumed that deleted zombie buffers can't have any
references in the context, so buffers were released sooner than they should
have been.

The fix is to count the non-atomic references in the new field
gl_buffer_object::CtxRefCount. When we detach the context from the buffer,
we can just add CtxRefCount to RefCount to re-enable atomic reference
counting. This also allows removing code that was doing a similar thing.

Fixes: e014e3b6be "mesa: don't count buffer references for the context that created them"
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/4259

Reviewed-by: Zoltán Böszörményi <zboszor@gmail.com>
Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9360>
This commit is contained in:
Marek Olšák 2021-03-02 01:38:26 -05:00 • committed by Marge Bot
parent a94bd9033d
commit ae0ce3e3ba
2 changed files with 37 additions and 105 deletions
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141
src/mesa/main/bufferobj.c
View file

@ -518,10 +518,15 @@ _mesa_reference_buffer_object_(struct gl_context *ctx,
* ptr is a binding point shared by multiple contexts (such as a texture
* buffer object being a buffer bound within a texture object).
*/
if ((shared_binding || ctx != oldObj->Ctx) &&
p_atomic_dec_zero(&oldObj->RefCount)) {
assert(ctx->Driver.DeleteBuffer);
ctx->Driver.DeleteBuffer(ctx, oldObj);
if (shared_binding || ctx != oldObj->Ctx) {
if (p_atomic_dec_zero(&oldObj->RefCount)) {
assert(ctx->Driver.DeleteBuffer);
ctx->Driver.DeleteBuffer(ctx, oldObj);
}
} else if (ctx == oldObj->Ctx) {
/* Update the private ref count. */
assert(oldObj->CtxRefCount >= 1);
oldObj->CtxRefCount--;
}
*ptr = NULL;
@ -532,6 +537,9 @@ _mesa_reference_buffer_object_(struct gl_context *ctx,
/* reference new buffer */
if (shared_binding || ctx != bufObj->Ctx)
p_atomic_inc(&bufObj->RefCount);
else if (ctx == bufObj->Ctx)
bufObj->CtxRefCount++;
*ptr = bufObj;
}
}
@ -911,6 +919,27 @@ _mesa_init_buffer_objects( struct gl_context *ctx )
}
}
/**
* Detach the context from the buffer to re-enable buffer reference counting
* for this context.
*/
static void
detach_ctx_from_buffer(struct gl_context *ctx, struct gl_buffer_object *buf)
{
assert(buf->Ctx == ctx);
/* Move private non-atomic context references to the global ref count. */
p_atomic_add(&buf->RefCount, buf->CtxRefCount);
buf->CtxRefCount = 0;
buf->Ctx = NULL;
/* Remove the context reference where the context holds one
* reference for the lifetime of the buffer ID to skip refcount
* atomics instead of each binding point holding the reference.
*/
_mesa_reference_buffer_object(ctx, &buf, NULL);
}
/**
* Zombie buffers are buffers that were created by one context and deleted
* by another context. The creating context holds a global reference for each
@ -932,8 +961,7 @@ unreference_zombie_buffers_for_ctx(struct gl_context *ctx)
if (buf->Ctx == ctx) {
_mesa_set_remove(ctx->Shared->ZombieBufferObjects, entry);
buf->Ctx = NULL;
_mesa_reference_buffer_object(ctx, &buf, NULL);
detach_ctx_from_buffer(ctx, buf);
}
}
}
@ -960,6 +988,7 @@ detach_unrefcounted_buffer_from_ctx(void *data, void *userData)
* unreference the global reference. Other contexts and texture objects
* might still be using the buffer.
*/
assert(buf->CtxRefCount == 0);
buf->Ctx = NULL;
_mesa_reference_buffer_object(ctx, &buf, NULL);
}
@ -1530,82 +1559,6 @@ bind_buffer_base_atomic_buffer(struct gl_context *ctx,
bind_atomic_buffer(ctx, index, bufObj, 0, 0, GL_TRUE);
}
struct hash_walk_input {
struct gl_context *ctx;
struct gl_buffer_object *buf;
};
/**
* When a buffer ID is deleted, the buffer is unbound from the current VAO
* but stays bound in other VAOs until they are deleted too.
* When the context owns the buffer reference globally, it doesn't count
* buffer references for the context. When the buffer is deleted, the context
* gives up its ownership, and thus it has to increase the buffer reference
* count for each binding point where the buffer is bound.
*/
static void
detach_ctx_from_vao_buffers(void *data, void *user)
{
struct gl_context *ctx = ((struct hash_walk_input *)user)->ctx;
struct gl_buffer_object *buf = ((struct hash_walk_input *)user)->buf;
struct gl_vertex_array_object *vao = (struct gl_vertex_array_object *)data;
/* The buffer should already be unbound in the currently-bound VAO. */
if (vao == ctx->Array.VAO)
return;
/* Increase the reference count for each binding point where the buffer is
* bound.
*/
unsigned add_count = 0;
if (vao->IndexBufferObj == buf)
add_count++;
for (unsigned i = 0; i < ARRAY_SIZE(vao->BufferBinding); i++) {
if (vao->BufferBinding[i].BufferObj == buf)
add_count++;
}
if (add_count)
p_atomic_add(&buf->RefCount, add_count);
}
/**
* When a buffer ID is deleted, the buffer is unbound from the current
* transform feedback object but stays bound in other TFBs until they are
* deleted too.
*
* When the context owns the buffer reference globally, it doesn't count
* buffer references for the context. When the buffer is deleted, the context
* gives up its ownership, and thus it has to increase the buffer reference
* count for each binding point where the buffer is bound.
*/
static void
detach_ctx_from_tfb_buffers(void *data, void *user)
{
struct gl_context *ctx = ((struct hash_walk_input *)user)->ctx;
struct gl_buffer_object *buf = ((struct hash_walk_input *)user)->buf;
struct gl_transform_feedback_object *tfb =
(struct gl_transform_feedback_object *)data;
/* The buffer should already be unbound in the currently-bound TFB. */
if (tfb == ctx->TransformFeedback.CurrentObject)
return;
/* Increase the reference count for each binding point where the buffer is
* bound.
*/
unsigned add_count = 0;
for (unsigned i = 0; i < ARRAY_SIZE(tfb->Buffers); i++) {
if (tfb->Buffers[i] == buf)
add_count++;
}
if (add_count)
p_atomic_add(&buf->RefCount, add_count);
}
/**
* Delete a set of buffer objects.
*
@ -1748,29 +1701,7 @@ delete_buffers(struct gl_context *ctx, GLsizei n, const GLuint *ids)
bufObj->DeletePending = GL_TRUE;
if (bufObj->Ctx == ctx) {
struct hash_walk_input input = {ctx, bufObj};
/* Increase reference counts for all binding points where
* the buffer remains bound after deleting. This is needed to
* enable reference counting for the buffer for this context
* because the context only holds the global buffer reference
* while the GL buffer ID exists.
*/
_mesa_HashWalk(ctx->Array.Objects,
detach_ctx_from_vao_buffers, &input);
detach_ctx_from_vao_buffers(ctx->Array.DefaultVAO, &input);
_mesa_HashWalk(ctx->TransformFeedback.Objects,
detach_ctx_from_tfb_buffers, &input);
detach_ctx_from_tfb_buffers(ctx->TransformFeedback.DefaultObject,
&input);
/* Remove the context reference where the context holds one
* reference for the lifetime of the buffer ID to skip refcount
* atomics instead of each binding point holding the reference.
*/
p_atomic_dec(&bufObj->RefCount);
bufObj->Ctx = NULL;
detach_ctx_from_buffer(ctx, bufObj);
} else if (bufObj->Ctx) {
/* Only the context holding it can release it. */
_mesa_set_add(ctx->Shared->ZombieBufferObjects, bufObj);

1
src/mesa/main/mtypes.h
View file

@ -1427,6 +1427,7 @@ struct gl_buffer_object
* reference from those buffers that it created.
*/
struct gl_context *Ctx;
GLint CtxRefCount; /**< Non-atomic references held by Ctx. */
GLenum16 Usage; /**< GL_STREAM_DRAW_ARB, GL_STREAM_READ_ARB, etc. */
GLbitfield StorageFlags; /**< GL_MAP_PERSISTENT_BIT, etc. */