Re: [PATCH v3 1/7] drm: Add common fdinfo helper

Daniel Vetter
2023-04-12T07:55:33Z

On Tue, Apr 11, 2023 at 03:56:06PM -0700, Rob Clark wrote:
> From: Rob Clark <robdclark@chromium.org>
>
> Handle a bit of the boiler-plate in a single case, and make it easier to
> add some core tracked stats.
>
> Signed-off-by: Rob Clark <robdclark@chromium.org>

Thanks a lot for kicking this off. A few polish comments below, with those
addressed:

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> ---
> drivers/gpu/drm/drm_file.c | 39 ++++++++++++++++++++++++++++++++++++++
> include/drm/drm_drv.h | 7 +++++++
> include/drm/drm_file.h | 4 ++++
> 3 files changed, 50 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
> index a51ff8cee049..37dfaa6be560 100644
> --- a/drivers/gpu/drm/drm_file.c
> +++ b/drivers/gpu/drm/drm_file.c
> @@ -148,6 +148,7 @@ bool drm_dev_needs_global_mutex(struct drm_device *dev)
> */
> struct drm_file *drm_file_alloc(struct drm_minor *minor)
> {
> + static atomic_t ident = ATOMIC_INIT(0);

Maybe make this atomic64_t just to be sure?

> struct drm_device *dev = minor->dev;
> struct drm_file *file;
> int ret;
> @@ -156,6 +157,8 @@ struct drm_file *drm_file_alloc(struct drm_minor *minor)
> if (!file)
> return ERR_PTR(-ENOMEM);
>
> + /* Get a unique identifier for fdinfo: */
> + file->client_id = atomic_inc_return(&ident) - 1;
> file->pid = get_pid(task_pid(current));
> file->minor = minor;
>
> @@ -868,6 +871,42 @@ void drm_send_event(struct drm_device *dev, struct drm_pending_event *e)
> }
> EXPORT_SYMBOL(drm_send_event);
>
> +/**
> + * drm_fop_show_fdinfo - helper for drm file fops
> + * @seq_file: output stream
> + * @f: the device file instance
> + *
> + * Helper to implement fdinfo, for userspace to query usage stats, etc, of a
> + * process using the GPU.

Please mention drm_driver.show_fd_info here too.

> + */
> +void drm_fop_show_fdinfo(struct seq_file *m, struct file *f)
> +{
> + struct drm_file *file = f->private_data;
> + struct drm_device *dev = file->minor->dev;
> + struct drm_printer p = drm_seq_file_printer(m);
> +
> + /*
> + * ******************************************************************
> + * For text output format description please see drm-usage-stats.rst!
> + * ******************************************************************

Maybe move this into the kerneldoc comment above (perhaps with an
IMPORTANT: tag or something, and make it an actual link)?

Also in the drm-usage-stats.rst please put a link to this function and
that is must be used for implementing fd_info.

> + */
> +
> + drm_printf(&p, "drm-driver:\t%s\n", dev->driver->name);
> + drm_printf(&p, "drm-client-id:\t%u\n", file->client_id);
> +
> + if (dev_is_pci(dev->dev)) {
> + struct pci_dev *pdev = to_pci_dev(dev->dev);
> +
> + drm_printf(&p, "drm-pdev:\t%04x:%02x:%02x.%d\n",
> + pci_domain_nr(pdev->bus), pdev->bus->number,
> + PCI_SLOT(pdev->devfn), PCI_FUNC(pdev->devfn));
> + }
> +
> + if (dev->driver->show_fdinfo)
> + dev->driver->show_fdinfo(&p, file);
> +}
> +EXPORT_SYMBOL(drm_fop_show_fdinfo);

Bit a bikeshed, but for consistency drop the _fop_? We don't have it for
any of the other drm fops and git grep doesn't show a naming conflict.

> +
> /**
> * mock_drm_getfile - Create a new struct file for the drm device
> * @minor: drm minor to wrap (e.g. #drm_device.primary)
> diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
> index 5b86bb7603e7..a883c6d3bcdf 100644
> --- a/include/drm/drm_drv.h
> +++ b/include/drm/drm_drv.h
> @@ -401,6 +401,13 @@ struct drm_driver {
> struct drm_device *dev, uint32_t handle,
> uint64_t *offset);
>
> + /**
> + * @fdinfo:
> + *
> + * Print device specific fdinfo. See drm-usage-stats.rst.

Please make this a link. I like links in kerneldoc :-)

> + */
> + void (*show_fdinfo)(struct drm_printer *p, struct drm_file *f);
> +
> /** @major: driver major number */
> int major;
> /** @minor: driver minor number */
> diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h
> index 0d1f853092ab..dfa995b787e1 100644
> --- a/include/drm/drm_file.h
> +++ b/include/drm/drm_file.h
> @@ -258,6 +258,9 @@ struct drm_file {
> /** @pid: Process that opened this file. */
> struct pid *pid;
>
> + /** @client_id: A unique id for fdinfo */
> + u32 client_id;
> +
> /** @magic: Authentication magic, see @authenticated. */
> drm_magic_t magic;
>
> @@ -437,6 +440,7 @@ void drm_send_event(struct drm_device *dev, struct drm_pending_event *e);
> void drm_send_event_timestamp_locked(struct drm_device *dev,
> struct drm_pending_event *e,
> ktime_t timestamp);
> +void drm_fop_show_fdinfo(struct seq_file *m, struct file *f);
>
> struct file *mock_drm_getfile(struct drm_minor *minor, unsigned int flags);
>
> --
> 2.39.2
>

--
Daniel Vetter
Software Engineer, Intel Corporation