linux-kernel - RE: [PATCH] drm/hyperv: Don't overwrite dirt

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Date:   Thu, 22 Sep 2022 22:46:13 +0000
From:   "Michael Kelley (LINUX)" <mikelley@...rosoft.com>
To:     Saurabh Sengar <ssengar@...ux.microsoft.com>,
        Saurabh Singh Sengar <ssengar@...rosoft.com>,
        "drawat.floss@...il.com" <drawat.floss@...il.com>,
        "airlied@...ux.ie" <airlied@...ux.ie>,
        "daniel@...ll.ch" <daniel@...ll.ch>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] drm/hyperv: Don't overwrite dirt_needed value set by host

From: Saurabh Sengar <ssengar@...ux.microsoft.com> Sent: Monday, September 12, 2022 8:33 AM
> 
> 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@...ux.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 4a8941fa0815..57d49a08b37f 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;
> --
> 2.31.1

Reviewed-by: Michael Kelley <mikelley@...rosoft.com>