[PATCH 5.15] drm/hyperv: Don't overwrite dirt_needed value set by host

[PATCH 5.15] drm/hyperv: Don't overwrite dirt_needed value set by host

[Saurabh Sengar]

[ Upstream commit 19b5e6659eaf537ebeac90ae30c7df0296fe5ab9 ]

Existing code is causing a race condition where dirt_needed value is
already set by the host and gets overwritten with default value. Remove
this default setting of dirt_needed, to avoid overwriting the value
received in the channel callback set by vmbus_open. Removing this
setting also means the default value for dirt_needed is changed to false
as it's allocated by kzalloc which is similar to legacy hyperv_fb driver.

Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Dexuan Cui <decui@microsoft.com>
---
 drivers/gpu/drm/hyperv/hyperv_drm_drv.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/gpu/drm/hyperv/hyperv_drm_drv.c b/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
index 00e53de4812b..584d3a73db96 100644
--- a/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
+++ b/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
@@ -198,8 +198,6 @@ static int hyperv_vmbus_probe(struct hv_device *hdev,
 	if (ret)
 		drm_warn(dev, "Failed to update vram location.\n");
 
-	hv->dirt_needed = true;
-
 	ret = hyperv_mode_config_init(hv);
 	if (ret)
 		goto err_vmbus_close;
-- 
2.34.1

Re: [PATCH 5.15] drm/hyperv: Don't overwrite dirt_needed value set by host

[Sasha Levin]

On Mon, May 08, 2023 at 03:30:02AM -0700, Saurabh Sengar wrote:
>[ Upstream commit 19b5e6659eaf537ebeac90ae30c7df0296fe5ab9 ]
>
>Existing code is causing a race condition where dirt_needed value is
>already set by the host and gets overwritten with default value. Remove
>this default setting of dirt_needed, to avoid overwriting the value
>received in the channel callback set by vmbus_open. Removing this
>setting also means the default value for dirt_needed is changed to false
>as it's allocated by kzalloc which is similar to legacy hyperv_fb driver.
>
>Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
>Reviewed-by: Michael Kelley <mikelley@microsoft.com>
>Reviewed-by: Dexuan Cui <decui@microsoft.com>

Queued up, thanks!

-- 
Thanks,
Sasha