[PATCH v2 2/9] drm: Add common fdinfo helper

Rob Clark
2023-04-27T17:54:11Z

Handle a bit of the boiler-plate in a single case, and make it easier to
add some core tracked stats. This also ensures consistent behavior
across drivers for standardised fields.

v2: Update drm-usage-stats.rst, 64b client-id, rename drm_show_fdinfo

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Rob Clark <robdclark@chromium.org>
---
Documentation/gpu/drm-usage-stats.rst | 10 +++++++-
drivers/gpu/drm/drm_file.c | 35 +++++++++++++++++++++++++++
include/drm/drm_drv.h | 7 ++++++
include/drm/drm_file.h | 4 +++
4 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/Documentation/gpu/drm-usage-stats.rst b/Documentation/gpu/drm-usage-stats.rst
index 72d069e5dacb..552195fb1ea3 100644
--- a/Documentation/gpu/drm-usage-stats.rst
+++ b/Documentation/gpu/drm-usage-stats.rst
@@ -126,7 +126,15 @@ percentage utilization of the engine, whereas drm-engine-<str> only reflects
time active without considering what frequency the engine is operating as a
percentage of it's maximum frequency.

+Implementation Details
+======================
+
+Drivers should use drm_show_fdinfo() in their `struct file_operations`, and
+implement &drm_driver.show_fdinfo if they wish to provide any stats which
+are not provided by drm_show_fdinfo(). But even driver specific stats should
+be documented above and where possible, aligned with other drivers.
+
Driver specific implementations
-===============================
+-------------------------------

:ref:`i915-usage-stats`
diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
index a51ff8cee049..6d5bdd684ae2 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 atomic64_t ident = ATOMIC_INIT(0);
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 = atomic64_inc_return(&ident);
file->pid = get_pid(task_pid(current));
file->minor = minor;

@@ -868,6 +871,38 @@ void drm_send_event(struct drm_device *dev, struct drm_pending_event *e)
}
EXPORT_SYMBOL(drm_send_event);

+/**
+ * drm_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. See also &drm_driver.show_fdinfo.
+ *
+ * For text output format description please see Documentation/gpu/drm-usage-stats.rst
+ */
+void drm_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);
+
+ drm_printf(&p, "drm-driver:\t%s\n", dev->driver->name);
+ drm_printf(&p, "drm-client-id:\t%llu\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_show_fdinfo);
+
/**
* 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..5edf2a13733b 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);

+ /**
+ * @show_fdinfo:
+ *
+ * Print device specific fdinfo. See Documentation/gpu/drm-usage-stats.rst.
+ */
+ 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..6de6d0e9c634 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 */
+ u64 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_show_fdinfo(struct seq_file *m, struct file *f);

struct file *mock_drm_getfile(struct drm_minor *minor, unsigned int flags);

--
2.39.2