Re: [PATCH v4] drm/ioctl: Add a ioctl to label GEM objects

Hello Rohan,

On Fri, 11 Oct 2019 16:30:09 +0200 Rohan Garg rohan.garg@collabora.com wrote:

DRM_IOCTL_DUMB_SET_LABEL lets you label GEM objects, making it easier to debug issues in userspace applications.

Changes in v2:

• Hoist the IOCTL up into the drm_driver framework

Changes in v3:

• Introduce a drm_gem_set_label for drivers to use internally in order to label a GEM object
• Hoist string copying up into the IOCTL
• Fix documentation
• Move actual gem labeling into drm_gem_adopt_label

Changes in v4:

• Refactor IOCTL call to only perform string duplication and move all gem lookup logic into GEM specific call

Signed-off-by: Rohan Garg rohan.garg@collabora.com

drivers/gpu/drm/drm_gem.c | 70 ++++++++++++++++++++++++++++++++++ drivers/gpu/drm/drm_internal.h | 8 ++++ drivers/gpu/drm/drm_ioctl.c | 1 + include/drm/drm_drv.h | 16 ++++++++ include/drm/drm_gem.h | 7 ++++ include/uapi/drm/drm.h | 20 ++++++++++ 6 files changed, 122 insertions(+)

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c index 6854f5867d51..0fa4609b2817 100644 --- a/drivers/gpu/drm/drm_gem.c +++ b/drivers/gpu/drm/drm_gem.c @@ -941,6 +941,71 @@ drm_gem_release(struct drm_device *dev, struct drm_file *file_private) idr_destroy(&file_private->object_idr); }

+int drm_dumb_set_label_ioctl(struct drm_device *dev,

Why dumb? Not sure what a smart set_label_ioctl() function would do differently :-).

Oh, and if this function can be used to label TTM BOs it should be moved somewhere else (drm_ioctl.c ?).

• 		void *data, struct drm_file *file_priv)
  

Indentation is broken here.

+{

• char *label;
• struct drm_dumb_set_label_object *args = data;
• int ret = 0;
• if (!args->len || !args->name)

Hm, I thought args->len == 0 was a valid case and meant "free the existing label". Has it changed. The case that's not allowed is args->len && !args->name.

• return -EINVAL;
  

• if (!dev->driver->label)

• return -EOPNOTSUPP;
  

• label = strndup_user(u64_to_user_ptr(args->name), args->len);

Remove this blank line.

• if (IS_ERR(label)) {

• ret = PTR_ERR(label);
  

• goto err;
  

• }
• ret = dev->driver->label(dev, file_priv, args->handle, label);

+err:

I would s/err/out/ as this is not an error-only path.

• kfree(label);
• return ret;

+}

+int drm_gem_set_label(struct drm_device *dev,

•        struct drm_file *file_priv,
  

• 	   uint32_t handle,
  

• 	   const char *label)
  

+{

• struct drm_gem_object *gem_obj;
• int ret = 0;
• gem_obj = drm_gem_object_lookup(file_priv, handle);
• if (!gem_obj) {

• DRM_DEBUG("Failed to look up GEM BO %d\n", handle);
  

• ret = -ENOENT;
  

• goto err;
  

• }
• drm_gem_adopt_label(gem_obj, label);

+err:

Ditto: s/err/out/

• drm_gem_object_put_unlocked(gem_obj);
• return ret;

+} +EXPORT_SYMBOL(drm_gem_set_label);

+void drm_gem_adopt_label(struct drm_gem_object *gem_obj, const char *label) +{

• char *adopted_label = NULL;
• if (label)

• adopted_label = kstrdup(label, GFP_KERNEL);
  

Add

WARN_ON(adopted_label);

• if (gem_obj->label) {

• kfree(gem_obj->label);
  

• gem_obj->label = NULL;
  

This assignment is useless since gem_obj->label is assigned below.

• }
• gem_obj->label = adopted_label;

+} +EXPORT_SYMBOL(drm_gem_adopt_label);

/**

• drm_gem_object_release - release GEM buffer object resources
• @obj: GEM buffer object

@@ -958,6 +1023,11 @@ drm_gem_object_release(struct drm_gem_object *obj)

dma_resv_fini(&obj->_resv); drm_gem_free_mmap_offset(obj);

• if (obj->label) {

• kfree(obj->label);
  

• obj->label = NULL;
  

• }

You can call kfree(obj->label) directly (kfree() checks for NULL vals), and no need to reset obj->label (obj should be free when the function returns).

} EXPORT_SYMBOL(drm_gem_object_release);

diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h index 51a2055c8f18..cbc3f7b7fb9b 100644 --- a/drivers/gpu/drm/drm_internal.h +++ b/drivers/gpu/drm/drm_internal.h @@ -137,6 +137,14 @@ int drm_gem_pin(struct drm_gem_object *obj); void drm_gem_unpin(struct drm_gem_object *obj); void *drm_gem_vmap(struct drm_gem_object *obj); void drm_gem_vunmap(struct drm_gem_object *obj, void *vaddr); +int drm_dumb_set_label_ioctl(struct drm_device *dev,

• 	void *data,
  

• 	struct drm_file *file_priv);
  

+int drm_gem_set_label(struct drm_device *dev,

• 	struct drm_file *file_priv,
  

• 	uint32_t handle,
  

• 	const char *label);
  

+void drm_gem_adopt_label(struct drm_gem_object *gem_obj, const char *label);

/* drm_debugfs.c drm_debugfs_crc.c */ #if defined(CONFIG_DEBUG_FS) diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c index fcd728d7cf72..f34e1571d70f 100644 --- a/drivers/gpu/drm/drm_ioctl.c +++ b/drivers/gpu/drm/drm_ioctl.c @@ -714,6 +714,7 @@ static const struct drm_ioctl_desc drm_ioctls[] = { DRM_IOCTL_DEF(DRM_IOCTL_MODE_LIST_LESSEES, drm_mode_list_lessees_ioctl, DRM_MASTER), DRM_IOCTL_DEF(DRM_IOCTL_MODE_GET_LEASE, drm_mode_get_lease_ioctl, DRM_MASTER), DRM_IOCTL_DEF(DRM_IOCTL_MODE_REVOKE_LEASE, drm_mode_revoke_lease_ioctl, DRM_MASTER),

• DRM_IOCTL_DEF(DRM_IOCTL_DUMB_SET_LABEL, drm_dumb_set_label_ioctl, DRM_RENDER_ALLOW),

};

#define DRM_CORE_IOCTL_COUNT ARRAY_SIZE( drm_ioctls ) diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h index cf13470810a5..501a3924354a 100644 --- a/include/drm/drm_drv.h +++ b/include/drm/drm_drv.h @@ -715,6 +715,22 @@ struct drm_driver { struct drm_device *dev, uint32_t handle);

• /**

• * @label:
  

• *
  

• * This label's a buffer object.
  

• *
  

• * Called by the user via ioctl.
  

• *
  

• * Returns:
  

• *
  

• * Zero on success, negative errno on failure.
  

• */
  

• int (*label)(struct drm_device *dev,

Maybe label_bo or set_bo_label instead of just label, just to make it clear that the label is applied to a buffer object.

• 		struct drm_file *file_priv,
  

• 		uint32_t handle,
  

• 		char *label);
  

Indentation issue here as well.

• /**
  • @gem_vm_ops: Driver private ops for this object

diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h index 6aaba14f5972..f801c054e972 100644 --- a/include/drm/drm_gem.h +++ b/include/drm/drm_gem.h @@ -237,6 +237,13 @@ struct drm_gem_object { */ int name;

• /**

• * @label:
  

• *
  

• * Label for this object, should be a human readable string.
  

• */
  

• char *label;
• /**
  • @dma_buf:

diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h index 8a5b2f8f8eb9..309c3c091385 100644 --- a/include/uapi/drm/drm.h +++ b/include/uapi/drm/drm.h @@ -626,6 +626,25 @@ struct drm_gem_open { __u64 size; };

+/** struct drm_dumb_set_label_object - ioctl argument for labelling BOs.

• • This label's a BO with a userspace label
• */

+struct drm_dumb_set_label_object {

• /** Handle for the object being labelled. */
• __u32 handle;
• /** Label and label length.

• *  len includes the trailing NUL.
  

• */
  

Nitpick: the comment fits on a single line.

/** Label and label length (len includes the trailing NUL). */

• __u32 len;
• __u64 name;
• /** Flags */
• int flags;

+};

#define DRM_CAP_DUMB_BUFFER 0x1 #define DRM_CAP_VBLANK_HIGH_CRTC 0x2 #define DRM_CAP_DUMB_PREFERRED_DEPTH 0x3 @@ -946,6 +965,7 @@ extern "C" { #define DRM_IOCTL_SYNCOBJ_QUERY DRM_IOWR(0xCB, struct drm_syncobj_timeline_array) #define DRM_IOCTL_SYNCOBJ_TRANSFER DRM_IOWR(0xCC, struct drm_syncobj_transfer) #define DRM_IOCTL_SYNCOBJ_TIMELINE_SIGNAL DRM_IOWR(0xCD, struct drm_syncobj_timeline_array) +#define DRM_IOCTL_DUMB_SET_LABEL DRM_IOWR(0xCE, struct drm_dumb_set_label_object)

Maybe s/DRM_IOCTL_DUMB_SET_LABEL/DRM_IOCTL_SET_BO_LABEL/ and s/drm_dumb_set_label_object/drm_set_bo_label/

/**

• Device specific ioctls should only be in their respective headers