Messages in this thread | | | Date | Fri, 3 Nov 2023 08:18:35 +0100 | Subject | Re: [PATCH drm-misc-next v8 09/12] drm/gpuvm: reference count drm_gpuvm structures | From | Christian König <> |
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Am 02.11.23 um 00:31 schrieb Danilo Krummrich: > Implement reference counting for struct drm_gpuvm.
From the design point of view what is that good for?
Background is that the most common use case I see is that this object is embedded into something else and a reference count is then not really a good idea.
Thanks, Christian.
> > Signed-off-by: Danilo Krummrich <dakr@redhat.com> > --- > drivers/gpu/drm/drm_gpuvm.c | 44 +++++++++++++++++++------- > drivers/gpu/drm/nouveau/nouveau_uvmm.c | 20 +++++++++--- > include/drm/drm_gpuvm.h | 31 +++++++++++++++++- > 3 files changed, 78 insertions(+), 17 deletions(-) > > diff --git a/drivers/gpu/drm/drm_gpuvm.c b/drivers/gpu/drm/drm_gpuvm.c > index 53e2c406fb04..6a88eafc5229 100644 > --- a/drivers/gpu/drm/drm_gpuvm.c > +++ b/drivers/gpu/drm/drm_gpuvm.c > @@ -746,6 +746,8 @@ drm_gpuvm_init(struct drm_gpuvm *gpuvm, const char *name, > gpuvm->rb.tree = RB_ROOT_CACHED; > INIT_LIST_HEAD(&gpuvm->rb.list); > > + kref_init(&gpuvm->kref); > + > gpuvm->name = name ? name : "unknown"; > gpuvm->flags = flags; > gpuvm->ops = ops; > @@ -770,15 +772,8 @@ drm_gpuvm_init(struct drm_gpuvm *gpuvm, const char *name, > } > EXPORT_SYMBOL_GPL(drm_gpuvm_init); > > -/** > - * drm_gpuvm_destroy() - cleanup a &drm_gpuvm > - * @gpuvm: pointer to the &drm_gpuvm to clean up > - * > - * Note that it is a bug to call this function on a manager that still > - * holds GPU VA mappings. > - */ > -void > -drm_gpuvm_destroy(struct drm_gpuvm *gpuvm) > +static void > +drm_gpuvm_fini(struct drm_gpuvm *gpuvm) > { > gpuvm->name = NULL; > > @@ -790,7 +785,33 @@ drm_gpuvm_destroy(struct drm_gpuvm *gpuvm) > > drm_gem_object_put(gpuvm->r_obj); > } > -EXPORT_SYMBOL_GPL(drm_gpuvm_destroy); > + > +static void > +drm_gpuvm_free(struct kref *kref) > +{ > + struct drm_gpuvm *gpuvm = container_of(kref, struct drm_gpuvm, kref); > + > + if (drm_WARN_ON(gpuvm->drm, !gpuvm->ops->vm_free)) > + return; > + > + drm_gpuvm_fini(gpuvm); > + > + gpuvm->ops->vm_free(gpuvm); > +} > + > +/** > + * drm_gpuvm_bo_put() - drop a struct drm_gpuvm reference > + * @gpuvm: the &drm_gpuvm to release the reference of > + * > + * This releases a reference to @gpuvm. > + */ > +void > +drm_gpuvm_put(struct drm_gpuvm *gpuvm) > +{ > + if (gpuvm) > + kref_put(&gpuvm->kref, drm_gpuvm_free); > +} > +EXPORT_SYMBOL_GPL(drm_gpuvm_put); > > static int > __drm_gpuva_insert(struct drm_gpuvm *gpuvm, > @@ -843,7 +864,7 @@ drm_gpuva_insert(struct drm_gpuvm *gpuvm, > if (unlikely(!drm_gpuvm_range_valid(gpuvm, addr, range))) > return -EINVAL; > > - return __drm_gpuva_insert(gpuvm, va); > + return __drm_gpuva_insert(drm_gpuvm_get(gpuvm), va); > } > EXPORT_SYMBOL_GPL(drm_gpuva_insert); > > @@ -876,6 +897,7 @@ drm_gpuva_remove(struct drm_gpuva *va) > } > > __drm_gpuva_remove(va); > + drm_gpuvm_put(va->vm); > } > EXPORT_SYMBOL_GPL(drm_gpuva_remove); > > diff --git a/drivers/gpu/drm/nouveau/nouveau_uvmm.c b/drivers/gpu/drm/nouveau/nouveau_uvmm.c > index 54be12c1272f..cb2f06565c46 100644 > --- a/drivers/gpu/drm/nouveau/nouveau_uvmm.c > +++ b/drivers/gpu/drm/nouveau/nouveau_uvmm.c > @@ -1780,6 +1780,18 @@ nouveau_uvmm_bo_unmap_all(struct nouveau_bo *nvbo) > } > } > > +static void > +nouveau_uvmm_free(struct drm_gpuvm *gpuvm) > +{ > + struct nouveau_uvmm *uvmm = uvmm_from_gpuvm(gpuvm); > + > + kfree(uvmm); > +} > + > +static const struct drm_gpuvm_ops gpuvm_ops = { > + .vm_free = nouveau_uvmm_free, > +}; > + > int > nouveau_uvmm_ioctl_vm_init(struct drm_device *dev, > void *data, > @@ -1830,7 +1842,7 @@ nouveau_uvmm_ioctl_vm_init(struct drm_device *dev, > NOUVEAU_VA_SPACE_END, > init->kernel_managed_addr, > init->kernel_managed_size, > - NULL); > + &gpuvm_ops); > /* GPUVM takes care from here on. */ > drm_gem_object_put(r_obj); > > @@ -1849,8 +1861,7 @@ nouveau_uvmm_ioctl_vm_init(struct drm_device *dev, > return 0; > > out_gpuvm_fini: > - drm_gpuvm_destroy(&uvmm->base); > - kfree(uvmm); > + drm_gpuvm_put(&uvmm->base); > out_unlock: > mutex_unlock(&cli->mutex); > return ret; > @@ -1902,7 +1913,6 @@ nouveau_uvmm_fini(struct nouveau_uvmm *uvmm) > > mutex_lock(&cli->mutex); > nouveau_vmm_fini(&uvmm->vmm); > - drm_gpuvm_destroy(&uvmm->base); > - kfree(uvmm); > + drm_gpuvm_put(&uvmm->base); > mutex_unlock(&cli->mutex); > } > diff --git a/include/drm/drm_gpuvm.h b/include/drm/drm_gpuvm.h > index 0c2e24155a93..4e6e1fd3485a 100644 > --- a/include/drm/drm_gpuvm.h > +++ b/include/drm/drm_gpuvm.h > @@ -247,6 +247,11 @@ struct drm_gpuvm { > struct list_head list; > } rb; > > + /** > + * @kref: reference count of this object > + */ > + struct kref kref; > + > /** > * @kernel_alloc_node: > * > @@ -273,7 +278,23 @@ void drm_gpuvm_init(struct drm_gpuvm *gpuvm, const char *name, > u64 start_offset, u64 range, > u64 reserve_offset, u64 reserve_range, > const struct drm_gpuvm_ops *ops); > -void drm_gpuvm_destroy(struct drm_gpuvm *gpuvm); > + > +/** > + * drm_gpuvm_get() - acquire a struct drm_gpuvm reference > + * @gpuvm: the &drm_gpuvm to acquire the reference of > + * > + * This function acquires an additional reference to @gpuvm. It is illegal to > + * call this without already holding a reference. No locks required. > + */ > +static inline struct drm_gpuvm * > +drm_gpuvm_get(struct drm_gpuvm *gpuvm) > +{ > + kref_get(&gpuvm->kref); > + > + return gpuvm; > +} > + > +void drm_gpuvm_put(struct drm_gpuvm *gpuvm); > > bool drm_gpuvm_range_valid(struct drm_gpuvm *gpuvm, u64 addr, u64 range); > bool drm_gpuvm_interval_empty(struct drm_gpuvm *gpuvm, u64 addr, u64 range); > @@ -673,6 +694,14 @@ static inline void drm_gpuva_init_from_op(struct drm_gpuva *va, > * operations to drivers. > */ > struct drm_gpuvm_ops { > + /** > + * @vm_free: called when the last reference of a struct drm_gpuvm is > + * dropped > + * > + * This callback is mandatory. > + */ > + void (*vm_free)(struct drm_gpuvm *gpuvm); > + > /** > * @op_alloc: called when the &drm_gpuvm allocates > * a struct drm_gpuva_op
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