[PATCH] drm: fix missing reference counting decrease

[PATCH] drm: fix missing reference counting decrease

[Insu Yun]

In drm_dp_mst_allocate_vcpi, it returns true in two paths,
but in one path, there is no reference couting decrease.

Signed-off-by: Insu Yun <wuninsu@gmail.com>
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 6ed90a2..fe273b6 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -2446,6 +2446,7 @@ bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp
 		DRM_DEBUG_KMS("payload: vcpi %d already allocated for pbn %d - requested pbn %d\n", port->vcpi.vcpi, port->vcpi.pbn, pbn);
 		if (pbn == port->vcpi.pbn) {
 			*slots = port->vcpi.num_slots;
+			drm_dp_put_port(port);
 			return true;
 		}
 	}
-- 
1.9.1

Re: [PATCH] drm: fix missing reference counting decrease

[Harry Wentland]

[-- Attachment #1: Type: text/plain, Size: 1048 bytes --]

This looks good but we should probably do the same for all return paths 
when reference for port has been acquired.

Please see attached patch.

Thanks,
Harry

On 2016-02-01 11:08 AM, Insu Yun wrote:
> In drm_dp_mst_allocate_vcpi, it returns true in two paths,
> but in one path, there is no reference couting decrease.
>
> Signed-off-by: Insu Yun <wuninsu@gmail.com>
> ---
>   drivers/gpu/drm/drm_dp_mst_topology.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
> index 6ed90a2..fe273b6 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -2446,6 +2446,7 @@ bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp
>   		DRM_DEBUG_KMS("payload: vcpi %d already allocated for pbn %d - requested pbn %d\n", port->vcpi.vcpi, port->vcpi.pbn, pbn);
>   		if (pbn == port->vcpi.pbn) {
>   			*slots = port->vcpi.num_slots;
> +			drm_dp_put_port(port);
>   			return true;
>   		}
>   	}


[-- Attachment #2: 0001-drm-dp-mst-Fix-missing-ref-count-decrease.patch --]
[-- Type: text/x-patch, Size: 1441 bytes --]

>From a6d4dc6206f06a3d1acc05ea5bf3b4885cc96a0a Mon Sep 17 00:00:00 2001
From: Harry Wentland <harry.wentland@amd.com>
Date: Tue, 9 Feb 2016 09:33:11 -0500
Subject: [PATCH] drm/dp/mst: Fix missing ref count decrease

Decrease ref count for port on all exit conditions.

Signed-off-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Mykola Lysenko <mykola.lysenko@amd.com>
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 5662e68ecccd..fa50fd0cb5ef 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -2498,7 +2498,8 @@ bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp
 		DRM_DEBUG_KMS("payload: vcpi %d already allocated for pbn %d - requested pbn %d\n", port->vcpi.vcpi, port->vcpi.pbn, pbn);
 		if (pbn == port->vcpi.pbn) {
 			*slots = port->vcpi.num_slots;
-			return true;
+			ret = 0;
+			goto out;
 		}
 	}
 
@@ -2510,10 +2511,10 @@ bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp
 	DRM_DEBUG_KMS("initing vcpi for %d %d\n", pbn, port->vcpi.num_slots);
 	*slots = port->vcpi.num_slots;
 
-	drm_dp_put_port(port);
-	return true;
+	ret = 0;
 out:
-	return false;
+	drm_dp_put_port(port);
+	return ret == 0;
 }
 EXPORT_SYMBOL(drm_dp_mst_allocate_vcpi);
 
-- 
2.1.4