linux-kernel - RE: [PATCH 023/190] Revert "drm/radeon: fix multiple reference count leak"

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Message-ID: <MN2PR12MB44889F62CD7F3EAC7572AEA2F7479@MN2PR12MB4488.namprd12.prod.outlook.com>
Date:   Wed, 21 Apr 2021 16:07:14 +0000
From:   "Deucher, Alexander" <Alexander.Deucher@....com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Aditya Pakki <pakki001@....edu>
Subject: RE: [PATCH 023/190] Revert "drm/radeon: fix multiple reference count
 leak"

[AMD Public Use]

> -----Original Message-----
> From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Sent: Wednesday, April 21, 2021 8:58 AM
> To: linux-kernel@...r.kernel.org
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>; Aditya Pakki
> <pakki001@....edu>; Deucher, Alexander
> <Alexander.Deucher@....com>
> Subject: [PATCH 023/190] Revert "drm/radeon: fix multiple reference count
> leak"
> 
> This reverts commit 6f2e8acdb48ed166b65d47837c31b177460491ec.
> 
> Commits from @umn.edu addresses have been found to be submitted in
> "bad faith" to try to test the kernel community's ability to review "known
> malicious" changes.  The result of these submissions can be found in a paper
> published at the 42nd IEEE Symposium on Security and Privacy entitled,
> "Open Source Insecurity: Stealthily Introducing Vulnerabilities via Hypocrite
> Commits" written by Qiushi Wu (University of Minnesota) and Kangjie Lu
> (University of Minnesota).
> 
> Because of this, all submissions from this group must be reverted from the
> kernel tree and will need to be re-reviewed again to determine if they
> actually are a valid fix.  Until that work is complete, remove this change to
> ensure that no problems are being introduced into the codebase.
> 
> Cc: Aditya Pakki <pakki001@....edu>
> Cc: Alex Deucher <alexander.deucher@....com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

AFAICT, this patch is correct or at least does no harm.  Handling of pm_runtime_get_sync() errors in the kernel seems to be inconsistent at best.

Alex

> ---
>  drivers/gpu/drm/radeon/radeon_connectors.c | 20 +++++---------------
>  1 file changed, 5 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c
> b/drivers/gpu/drm/radeon/radeon_connectors.c
> index 607ad5620bd9..ba8885676676 100644
> --- a/drivers/gpu/drm/radeon/radeon_connectors.c
> +++ b/drivers/gpu/drm/radeon/radeon_connectors.c
> @@ -879,10 +879,8 @@ radeon_lvds_detect(struct drm_connector
> *connector, bool force)
> 
>  	if (!drm_kms_helper_is_poll_worker()) {
>  		r = pm_runtime_get_sync(connector->dev->dev);
> -		if (r < 0) {
> -			pm_runtime_put_autosuspend(connector->dev-
> >dev);
> +		if (r < 0)
>  			return connector_status_disconnected;
> -		}
>  	}
> 
>  	if (encoder) {
> @@ -1027,10 +1025,8 @@ radeon_vga_detect(struct drm_connector
> *connector, bool force)
> 
>  	if (!drm_kms_helper_is_poll_worker()) {
>  		r = pm_runtime_get_sync(connector->dev->dev);
> -		if (r < 0) {
> -			pm_runtime_put_autosuspend(connector->dev-
> >dev);
> +		if (r < 0)
>  			return connector_status_disconnected;
> -		}
>  	}
> 
>  	encoder = radeon_best_single_encoder(connector);
> @@ -1167,10 +1163,8 @@ radeon_tv_detect(struct drm_connector
> *connector, bool force)
> 
>  	if (!drm_kms_helper_is_poll_worker()) {
>  		r = pm_runtime_get_sync(connector->dev->dev);
> -		if (r < 0) {
> -			pm_runtime_put_autosuspend(connector->dev-
> >dev);
> +		if (r < 0)
>  			return connector_status_disconnected;
> -		}
>  	}
> 
>  	encoder = radeon_best_single_encoder(connector);
> @@ -1253,10 +1247,8 @@ radeon_dvi_detect(struct drm_connector
> *connector, bool force)
> 
>  	if (!drm_kms_helper_is_poll_worker()) {
>  		r = pm_runtime_get_sync(connector->dev->dev);
> -		if (r < 0) {
> -			pm_runtime_put_autosuspend(connector->dev-
> >dev);
> +		if (r < 0)
>  			return connector_status_disconnected;
> -		}
>  	}
> 
>  	if (radeon_connector->detected_hpd_without_ddc) { @@ -1665,10
> +1657,8 @@ radeon_dp_detect(struct drm_connector *connector, bool
> force)
> 
>  	if (!drm_kms_helper_is_poll_worker()) {
>  		r = pm_runtime_get_sync(connector->dev->dev);
> -		if (r < 0) {
> -			pm_runtime_put_autosuspend(connector->dev-
> >dev);
> +		if (r < 0)
>  			return connector_status_disconnected;
> -		}
>  	}
> 
>  	if (!force && radeon_check_hpd_status_unchanged(connector)) {
> --
> 2.31.1