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");
On Tue, Jun 02, 2020 at 08:37:31PM -0700, Jeykumar Sankaran wrote:
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
Hm on the unregister side we don't have the race, there we remove everything and then send out the uevent. But there the uevent is also generated in a separate step, so I wonder whether we shouldn't do the same for register for symmetry ...
Anyway this looks good, nice catch, I'll add cc: stable and merge. -Daniel
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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