[PATCH v2 8/9] drm/fdinfo: Add comm/cmdline override fields

Rob Clark
2023-04-27T17:55:01Z

These are useful in particular for VM scenarios where the process which
has opened to drm device file is just a proxy for the real user in a VM
guest.

Signed-off-by: Rob Clark <robdclark@chromium.org>
---
Documentation/gpu/drm-usage-stats.rst | 18 ++++++++++++++++++
drivers/gpu/drm/drm_file.c | 15 +++++++++++++++
include/drm/drm_file.h | 19 +++++++++++++++++++
3 files changed, 52 insertions(+)

diff --git a/Documentation/gpu/drm-usage-stats.rst b/Documentation/gpu/drm-usage-stats.rst
index 58dc0d3f8c58..e4877cf8089c 100644
--- a/Documentation/gpu/drm-usage-stats.rst
+++ b/Documentation/gpu/drm-usage-stats.rst
@@ -73,6 +73,24 @@ scope of each device, in which case `drm-pdev` shall be present as well.
Userspace should make sure to not double account any usage statistics by using
the above described criteria in order to associate data to individual clients.

+- drm-comm-override: <valstr>
+
+Returns the client executable override string. Some drivers support letting
+userspace override this in cases where the userspace is simply a "proxy".
+Such as is the case with virglrenderer drm native context, where the host
+process is just forwarding command submission, etc, from guest userspace.
+This allows the proxy to make visible the executable name of the actual
+app in the VM guest.
+
+- drm-cmdline-override: <valstr>
+
+Returns the client cmdline override string. Some drivers support letting
+userspace override this in cases where the userspace is simply a "proxy".
+Such as is the case with virglrenderer drm native context, where the host
+process is just forwarding command submission, etc, from guest userspace.
+This allows the proxy to make visible the cmdline of the actual app in the
+VM guest.
+
Utilization
^^^^^^^^^^^

diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
index 9321eb0bf020..d7514c313af1 100644
--- a/drivers/gpu/drm/drm_file.c
+++ b/drivers/gpu/drm/drm_file.c
@@ -178,6 +178,8 @@ struct drm_file *drm_file_alloc(struct drm_minor *minor)
spin_lock_init(&file->master_lookup_lock);
mutex_init(&file->event_read_lock);

+ mutex_init(&file->override_lock);
+
if (drm_core_check_feature(dev, DRIVER_GEM))
drm_gem_open(dev, file);

@@ -292,6 +294,8 @@ void drm_file_free(struct drm_file *file)
WARN_ON(!list_empty(&file->event_list));

put_pid(file->pid);
+ kfree(file->override_comm);
+ kfree(file->override_cmdline);
kfree(file);
}

@@ -995,6 +999,17 @@ void drm_show_fdinfo(struct seq_file *m, struct file *f)
PCI_SLOT(pdev->devfn), PCI_FUNC(pdev->devfn));
}

+ mutex_lock(&file->override_lock);
+ if (file->override_comm) {
+ drm_printf(&p, "drm-comm-override:\t%s\n",
+ file->override_comm);
+ }
+ if (file->override_cmdline) {
+ drm_printf(&p, "drm-cmdline-override:\t%s\n",
+ file->override_cmdline);
+ }
+ mutex_unlock(&file->override_lock);
+
if (dev->driver->show_fdinfo)
dev->driver->show_fdinfo(&p, file);
}
diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h
index 1339e925af52..604d05fa6f0c 100644
--- a/include/drm/drm_file.h
+++ b/include/drm/drm_file.h
@@ -370,6 +370,25 @@ struct drm_file {
*/
struct drm_prime_file_private prime;

+ /**
+ * @comm: Overridden task comm
+ *
+ * Accessed under override_lock
+ */
+ char *override_comm;
+
+ /**
+ * @cmdline: Overridden task cmdline
+ *
+ * Accessed under override_lock
+ */
+ char *override_cmdline;
+
+ /**
+ * @override_lock: Serialize access to override_comm and override_cmdline
+ */
+ struct mutex override_lock;
+
/* private: */
#if IS_ENABLED(CONFIG_DRM_LEGACY)
unsigned long lock_count; /* DRI1 legacy lock count */
--
2.39.2