[PATCH v3 1/2] drm: Add GPU reset sysfs event

André Almeida
2022-11-25T17:52:40Z

From: Shashank Sharma <shashank.sharma@amd.com>

Add a sysfs event to notify userspace about GPU resets providing:
- PID that triggered the GPU reset, if any. Resets can happen from
kernel threads as well, in that case no PID is provided
- Information about the reset (e.g. was VRAM lost?)

Co-developed-by: André Almeida <andrealmeid@igalia.com>
Signed-off-by: André Almeida <andrealmeid@igalia.com>
Signed-off-by: Shashank Sharma <shashank.sharma@amd.com>
---

V3:
- Reduce information to just PID and flags
- Use pid pointer instead of just pid number
- BUG() if no reset info is provided

V2:
- Addressed review comments from Christian and Amar
- move the reset information structure to DRM layer
- drop _ctx from struct name
- make pid 32 bit(than 64)
- set flag when VRAM invalid (than valid)
- add process name as well (Amar)
---
drivers/gpu/drm/drm_sysfs.c | 26 ++++++++++++++++++++++++++
include/drm/drm_sysfs.h | 13 +++++++++++++
2 files changed, 39 insertions(+)

diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c
index 430e00b16eec..85777abf4194 100644
--- a/drivers/gpu/drm/drm_sysfs.c
+++ b/drivers/gpu/drm/drm_sysfs.c
@@ -409,6 +409,32 @@ void drm_sysfs_hotplug_event(struct drm_device *dev)
}
EXPORT_SYMBOL(drm_sysfs_hotplug_event);

+/**
+ * drm_sysfs_reset_event - generate a DRM uevent to indicate GPU reset
+ * @dev: DRM device
+ * @reset_info: The contextual information about the reset (like PID, flags)
+ *
+ * Send a uevent for the DRM device specified by @dev. This informs
+ * user that a GPU reset has occurred, so that an interested client
+ * can take any recovery or profiling measure.
+ */
+void drm_sysfs_reset_event(struct drm_device *dev, struct drm_reset_event_info *reset_info)
+{
+ unsigned char pid_str[13];
+ unsigned char flags_str[18];
+ unsigned char reset_str[] = "RESET=1";
+ char *envp[] = { reset_str, pid_str, flags_str, NULL };
+
+ DRM_DEBUG("generating reset event\n");
+
+ BUG_ON(!reset_info);
+
+ snprintf(pid_str, sizeof(pid_str), "PID=%u", pid_vnr(reset_info->pid));
+ snprintf(flags_str, sizeof(flags_str), "FLAGS=0x%llx", reset_info->flags);
+ kobject_uevent_env(&dev->primary->kdev->kobj, KOBJ_CHANGE, envp);
+}
+EXPORT_SYMBOL(drm_sysfs_reset_event);
+
/**
* drm_sysfs_connector_hotplug_event - generate a DRM uevent for any connector
* change
diff --git a/include/drm/drm_sysfs.h b/include/drm/drm_sysfs.h
index 6273cac44e47..dbb0ac6230b8 100644
--- a/include/drm/drm_sysfs.h
+++ b/include/drm/drm_sysfs.h
@@ -2,15 +2,28 @@
#ifndef _DRM_SYSFS_H_
#define _DRM_SYSFS_H_

+#define DRM_RESET_EVENT_VRAM_LOST (1 << 0)
+
struct drm_device;
struct device;
struct drm_connector;
struct drm_property;

+/**
+ * struct drm_reset_event_info - Information about a GPU reset event
+ * @pid: Process that triggered the reset, if any
+ * @flags: Extra information around the reset event (e.g. is VRAM lost?)
+ */
+struct drm_reset_event_info {
+ struct pid *pid;
+ uint64_t flags;
+};
+
int drm_class_device_register(struct device *dev);
void drm_class_device_unregister(struct device *dev);

void drm_sysfs_hotplug_event(struct drm_device *dev);
+void drm_sysfs_reset_event(struct drm_device *dev, struct drm_reset_event_info *reset_info);
void drm_sysfs_connector_hotplug_event(struct drm_connector *connector);
void drm_sysfs_connector_status_event(struct drm_connector *connector,
struct drm_property *property);
--
2.38.1