[PATCH] drm/connector: notify userspace on hotplug after register complete

Jeykumar Sankaran
2020-06-03T03:38:00Z

drm connector notifies userspace on hotplug event prematurely before
late_register and mode_object register completes. This leads to a race
between userspace and kernel on updating the IDR list. So, move the
notification to end of connector register.

Signed-off-by: Jeykumar Sankaran <jsanka@codeaurora.org>
Signed-off-by: Steve Cohen <cohens@codeaurora.org>
---
drivers/gpu/drm/drm_connector.c | 5 +++++
drivers/gpu/drm/drm_sysfs.c | 3 ---
2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index b1099e1..d877ddc 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -27,6 +27,7 @@
#include <drm/drm_print.h>
#include <drm/drm_drv.h>
#include <drm/drm_file.h>
+#include <drm/drm_sysfs.h>

#include <linux/uaccess.h>

@@ -523,6 +524,10 @@ int drm_connector_register(struct drm_connector *connector)
drm_mode_object_register(connector->dev, &connector->base);

connector->registration_state = DRM_CONNECTOR_REGISTERED;
+
+ /* Let userspace know we have a new connector */
+ drm_sysfs_hotplug_event(connector->dev);
+
goto unlock;

err_debugfs:
diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c
index 939f003..f0336c8 100644
--- a/drivers/gpu/drm/drm_sysfs.c
+++ b/drivers/gpu/drm/drm_sysfs.c
@@ -291,9 +291,6 @@ int drm_sysfs_connector_add(struct drm_connector *connector)
return PTR_ERR(connector->kdev);
}

- /* Let userspace know we have a new connector */
- drm_sysfs_hotplug_event(dev);
-
if (connector->ddc)
return sysfs_create_link(&connector->kdev->kobj,
&connector->ddc->dev.kobj, "ddc");
--
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a Linux Foundation Collaborative Project

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