[PATCH v2 1/2] drm: Add GPU reset sysfs event

[Shashank Sharma <contactshashanksharma@xxxxxxxxx>]

From: Shashank Sharma <shashank.sharma@xxxxxxx>

This patch adds a new sysfs event, which will indicate
the userland about a GPU reset, and can also provide
some information like:
- process ID of the process involved with the GPU reset
- process name of the involved process
- the GPU status info (using flags)

This patch also introduces the first flag of the flags
bitmap, which can be appended as and when required.

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)

Cc: Alexandar Deucher <alexander.deucher@xxxxxxx>
Cc: Christian Koenig <christian.koenig@xxxxxxx>
Cc: Amaranath Somalapuram <amaranath.somalapuram@xxxxxxx>
Signed-off-by: Shashank Sharma <shashank.sharma@xxxxxxx>
---
 drivers/gpu/drm/drm_sysfs.c | 31 +++++++++++++++++++++++++++++++
 include/drm/drm_sysfs.h     | 10 ++++++++++
 2 files changed, 41 insertions(+)

diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c
index 430e00b16eec..840994810910 100644
--- a/drivers/gpu/drm/drm_sysfs.c
+++ b/drivers/gpu/drm/drm_sysfs.c
@@ -409,6 +409,37 @@ 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 *reset_info)
+{
+	unsigned char pid_str[13];
+	unsigned char flags_str[15];
+	unsigned char pname_str[TASK_COMM_LEN + 6];
+	unsigned char reset_str[] = "RESET=1";
+	char *envp[] = { reset_str, pid_str, pname_str, flags_str, NULL };
+
+	if (!reset_info) {
+		DRM_WARN("No reset info, not sending the event\n");
+		return;
+	}
+
+	DRM_DEBUG("generating reset event\n");
+
+	snprintf(pid_str, ARRAY_SIZE(pid_str), "PID=%u", reset_info->pid);
+	snprintf(pname_str, ARRAY_SIZE(pname_str), "NAME=%s", reset_info->pname);
+	snprintf(flags_str, ARRAY_SIZE(flags_str), "FLAGS=%u", 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..5ba11c760619 100644
--- a/include/drm/drm_sysfs.h
+++ b/include/drm/drm_sysfs.h
@@ -1,16 +1,26 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #ifndef _DRM_SYSFS_H_
 #define _DRM_SYSFS_H_
+#include <linux/sched.h>
+
+#define DRM_GPU_RESET_FLAG_VRAM_INVALID (1 << 0)
 
 struct drm_device;
 struct device;
 struct drm_connector;
 struct drm_property;
 
+struct drm_reset_event {
+	uint32_t pid;
+	uint32_t flags;
+	char pname[TASK_COMM_LEN];
+};
+
 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 *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);
-- 
2.32.0