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Danilo Krummrich

2023-Nov-01 23:31 UTC

[Nouveau] [PATCH drm-misc-next v8 09/12] drm/gpuvm: reference count drm_gpuvm structures

Implement reference counting for struct drm_gpuvm.

Signed-off-by: Danilo Krummrich <dakr at 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
-- 
2.41.0

kernel test robot

2023-Nov-02 10:46 UTC

head link

[Nouveau] [PATCH drm-misc-next v8 09/12] drm/gpuvm: reference count drm_gpuvm structures

Hi Danilo,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 3c6c7ca4508b6cb1a033ac954c50a1b2c97af883]

url:   
https://github.com/intel-lab-lkp/linux/commits/Danilo-Krummrich/drm-gpuvm-convert-WARN-to-drm_WARN-variants/20231102-073332
base:   3c6c7ca4508b6cb1a033ac954c50a1b2c97af883
patch link:   
https://lore.kernel.org/r/20231101233113.8059-10-dakr%40redhat.com
patch subject: [PATCH drm-misc-next v8 09/12] drm/gpuvm: reference count
drm_gpuvm structures
config: arc-allmodconfig
(https://download.01.org/0day-ci/archive/20231102/202311021833.q8aYDJnr-lkp at
intel.com/config)
compiler: arceb-elf-gcc (GCC) 13.2.0
reproduce (this is a W=1 build):
(https://download.01.org/0day-ci/archive/20231102/202311021833.q8aYDJnr-lkp at
intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp at intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202311021833.q8aYDJnr-lkp at
intel.com/

All warnings (new ones prefixed by >>):
>> drivers/gpu/drm/drm_gpuvm.c:810: warning: expecting prototype for
drm_gpuvm_bo_put(). Prototype was for drm_gpuvm_put() instead

vim +810 drivers/gpu/drm/drm_gpuvm.c

   801	
   802	/**
   803	 * drm_gpuvm_bo_put() - drop a struct drm_gpuvm reference
   804	 * @gpuvm: the &drm_gpuvm to release the reference of
   805	 *
   806	 * This releases a reference to @gpuvm.
   807	 */
   808	void
   809	drm_gpuvm_put(struct drm_gpuvm *gpuvm)
 > 810	{
   811		if (gpuvm)
   812			kref_put(&gpuvm->kref, drm_gpuvm_free);
   813	}
   814	EXPORT_SYMBOL_GPL(drm_gpuvm_put);
   815	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Thomas Hellström

2023-Nov-02 13:21 UTC

head link

[Nouveau] [PATCH drm-misc-next v8 09/12] drm/gpuvm: reference count drm_gpuvm structures

On Thu, 2023-11-02 at 00:31 +0100, Danilo Krummrich
wrote:> Implement reference counting for struct drm_gpuvm.
> 
> Signed-off-by: Danilo Krummrich <dakr at redhat.com>
Will port the Xe series over to check that it works properly and get
back with review on this one.

> ---
> ?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

Thomas Hellström

2023-Nov-02 17:09 UTC

head link

[Nouveau] [PATCH drm-misc-next v8 09/12] drm/gpuvm: reference count drm_gpuvm structures

On Thu, 2023-11-02 at 00:31 +0100, Danilo Krummrich
wrote:> Implement reference counting for struct drm_gpuvm.
> 
> Signed-off-by: Danilo Krummrich <dakr at 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 referencecopy-paste error in function name.

Also it appears like xe might put a vm from irq context so we should
document the context where this function call is allowable, and if
applicable add a might_sleep().

If this function needs to sleep we can work around that in Xe by
keeping an xe-private refcount for the xe vm container, but I'd like to
avoid that if possible and piggy-back on the refcount introduced here.
> + * @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);
Here we leak a reference if __drm_gpuva_insert() fails, and IMO the
reference should be taken where the pointer holding the reference is
assigned (in this case in __drm_gpuva_insert()), or document the
reference transfer from the argument close to the assignment.

But since a va itself is not refcounted it clearly can't outlive the
vm, so is a reference really needed here?

I'd suggest using an accessor that instead of using va->vm uses
va->vm_bo->vm, to avoid needing to worry about the vm->vm refcountaltoghether.

Thanks,
Thomas

Christian König

2023-Nov-03 07:18 UTC

head link

[Nouveau] [PATCH drm-misc-next v8 09/12] drm/gpuvm: reference count drm_gpuvm structures

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 at 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

Nouveau - Nov 2023 - [PATCH drm-misc-next v8 09/12] drm/gpuvm: reference count drm_gpuvm structures

[Nouveau] [PATCH drm-misc-next v8 09/12] drm/gpuvm: reference count drm_gpuvm structures

[Nouveau] [PATCH drm-misc-next v8 09/12] drm/gpuvm: reference count drm_gpuvm structures

[Nouveau] [PATCH drm-misc-next v8 09/12] drm/gpuvm: reference count drm_gpuvm structures

[Nouveau] [PATCH drm-misc-next v8 09/12] drm/gpuvm: reference count drm_gpuvm structures

[Nouveau] [PATCH drm-misc-next v8 09/12] drm/gpuvm: reference count drm_gpuvm structures