Re: [PATCH v2 4/9] drm/fb-helper: Push down modeset lock into FB helpers

Hi Thierry,

2016년 06월 08일 00:26에 Thierry Reding 이(가) 쓴 글:

From: Thierry Reding treding@nvidia.com

Move the modeset locking from drivers into FB helpers.

Signed-off-by: Thierry Reding treding@nvidia.com

drivers/gpu/drm/drm_fb_helper.c | 59 +++++++++++++++++++++++++--------- drivers/gpu/drm/i915/intel_dp_mst.c | 4 --- drivers/gpu/drm/radeon/radeon_dp_mst.c | 7 ---- 3 files changed, 44 insertions(+), 26 deletions(-)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index 9afd4208596f..252c7557bdb5 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -95,8 +95,8 @@ static LIST_HEAD(kernel_fb_helper_list);

• mmap page writes.

*/

-int drm_fb_helper_add_one_connector(struct drm_fb_helper *fb_helper,

• 		    struct drm_connector *connector)
  

+static int __drm_fb_helper_add_one_connector(struct drm_fb_helper *fb_helper,

• 			     struct drm_connector *connector)
  

{ struct drm_fb_helper_connector **temp; struct drm_fb_helper_connector *conn; @@ -129,6 +129,20 @@ int drm_fb_helper_add_one_connector(struct drm_fb_helper *fb_helper, fb_helper->connector_info[fb_helper->connector_count++] = conn; return 0; }

+int drm_fb_helper_add_one_connector(struct drm_fb_helper *fb_helper,

• 		    struct drm_connector *connector)
  

+{

• int err;
• mutex_lock(&fb_helper->dev->mode_config.mutex);
• err = __drm_fb_helper_add_one_connector(fb_helper, connector);

I think you don't need to make __drm_fb_helper_add_on_connector function but just you can implement the codes here instead. And the use of prefix '__' thing would not good. And my concern about this is that other drivers may need to call this function after taking a same mutex lock. Can you assure anyone not to call this function with mutex lock?

If there is such case then,

some_function() { mutex_lock(); ... mutex_unlock(); drm_fb_helper_add_one_connector(); ... }

So in this case, other users should consider to make sure to unlock before calling this function. That would be now really what you want.

Thanks, Inki Dae

• mutex_unlock(&fb_helper->dev->mode_config.mutex);
• return err;

+} EXPORT_SYMBOL(drm_fb_helper_add_one_connector);

/** @@ -155,28 +169,28 @@ int drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper) return 0;

mutex_lock(&dev->mode_config.mutex);

• drm_for_each_connector(connector, dev) {

• ret = drm_fb_helper_add_one_connector(fb_helper, connector);
  

• ret = __drm_fb_helper_add_one_connector(fb_helper, connector);
  

• if (ret) {
  

• 	for (i = 0; i < fb_helper->connector_count; i++) {
  

• 		kfree(fb_helper->connector_info[i]);
  

• 		fb_helper->connector_info[i] = NULL;
  

• 	}
  

I think all resources should be released by someone who allocated the resources in case of failure. I mean that if some routine of __drm_fb_helper_add_on_connector function failed than the function make sure to release the resources allocated. I know this is really not what you did but original code did. So how about cleanning up this thing?

Thanks, Inki Dae

• if (ret)
  

• 	goto fail;
  

• }
• mutex_unlock(&dev->mode_config.mutex);
• return 0;

-fail:

• for (i = 0; i < fb_helper->connector_count; i++) {

• kfree(fb_helper->connector_info[i]);
  

• fb_helper->connector_info[i] = NULL;
  

• 	fb_helper->connector_count = 0;
  

• 	break;
  

• }
  

  }

• fb_helper->connector_count = 0;

• mutex_unlock(&dev->mode_config.mutex);

  return ret;

} EXPORT_SYMBOL(drm_fb_helper_single_add_all_connectors);

-int drm_fb_helper_remove_one_connector(struct drm_fb_helper *fb_helper,

• 		       struct drm_connector *connector)
  

+static int __drm_fb_helper_remove_one_connector(struct drm_fb_helper *fb_helper,

• 				struct drm_connector *connector)
  

{ struct drm_fb_helper_connector *fb_helper_connector; int i, j; @@ -193,6 +207,7 @@ int drm_fb_helper_remove_one_connector(struct drm_fb_helper *fb_helper,

if (i == fb_helper->connector_count) return -EINVAL;

• fb_helper_connector = fb_helper->connector_info[i]; drm_connector_unreference(fb_helper_connector->connector);

@@ -204,6 +219,20 @@ int drm_fb_helper_remove_one_connector(struct drm_fb_helper *fb_helper,

return 0; }

+int drm_fb_helper_remove_one_connector(struct drm_fb_helper *fb_helper,

• 		       struct drm_connector *connector)
  

+{

• int err;
• mutex_lock(&fb_helper->dev->mode_config.mutex);
• err = __drm_fb_helper_remove_one_connector(fb_helper, connector);
• mutex_unlock(&fb_helper->dev->mode_config.mutex);
• return err;

+} EXPORT_SYMBOL(drm_fb_helper_remove_one_connector);

static void drm_fb_helper_save_lut_atomic(struct drm_crtc *crtc, struct drm_fb_helper *helper) diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c index 7a34090cef34..47c3980cb3b9 100644 --- a/drivers/gpu/drm/i915/intel_dp_mst.c +++ b/drivers/gpu/drm/i915/intel_dp_mst.c @@ -477,9 +477,7 @@ static void intel_dp_register_mst_connector(struct drm_connector *connector) { struct intel_connector *intel_connector = to_intel_connector(connector); struct drm_device *dev = connector->dev;

• drm_modeset_lock_all(dev); intel_connector_add_to_fbdev(intel_connector);
• drm_modeset_unlock_all(dev); drm_connector_register(&intel_connector->base);

}

@@ -492,10 +490,8 @@ static void intel_dp_destroy_mst_connector(struct drm_dp_mst_topology_mgr *mgr, intel_connector->unregister(intel_connector);

/* need to nuke the connector */

• drm_modeset_lock_all(dev); intel_connector_remove_from_fbdev(intel_connector); intel_connector->mst_port = NULL;

• drm_modeset_unlock_all(dev);

  drm_connector_unreference(&intel_connector->base); DRM_DEBUG_KMS("\n");

diff --git a/drivers/gpu/drm/radeon/radeon_dp_mst.c b/drivers/gpu/drm/radeon/radeon_dp_mst.c index de504ea29c06..a4ccaa5af104 100644 --- a/drivers/gpu/drm/radeon/radeon_dp_mst.c +++ b/drivers/gpu/drm/radeon/radeon_dp_mst.c @@ -299,9 +299,7 @@ static void radeon_dp_register_mst_connector(struct drm_connector *connector) struct drm_device *dev = connector->dev; struct radeon_device *rdev = dev->dev_private;

• drm_modeset_lock_all(dev); radeon_fb_add_connector(rdev, connector);

• drm_modeset_unlock_all(dev);

  drm_connector_register(connector);

} @@ -314,13 +312,8 @@ static void radeon_dp_destroy_mst_connector(struct drm_dp_mst_topology_mgr *mgr, struct radeon_device *rdev = dev->dev_private;

drm_connector_unregister(connector);

• /* need to nuke the connector */

• drm_modeset_lock_all(dev);

• /* dpms off */ radeon_fb_remove_connector(rdev, connector);

• drm_connector_cleanup(connector);

• drm_modeset_unlock_all(dev);

  kfree(connector); DRM_DEBUG_KMS("\n");