Subject: Re: [PATCH 3.4 065/125] drm/ttm: Fixed a read/write lock imbalance
To: <lizf@kernel.org>, <stable@vger.kernel.org>
References: <1476275600-4626-1-git-send-email-lizf@kernel.org>
 <1476275641-4697-65-git-send-email-lizf@kernel.org>
CC: <linux-kernel@vger.kernel.org>, Zefan Li <lizefan@huawei.com>
From: Thomas Hellstrom <thellstrom@vmware.com>
Message-ID: <cd653ffc-d7c9-4a6a-2b9c-0c2058cee4d0@vmware.com>
Date: Wed, 12 Oct 2016 15:04:45 +0200
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Li,

IIRC This one goes hand in hand with a vmwgfx (the only user) patch.
Please don't apply until I've figured out whether that patch is also in 3.4.

Thanks,
Thomas


On 10/12/2016 02:33 PM, lizf@kernel.org wrote:
> From: Thomas Hellstrom <thellstrom@vmware.com>
>
> 3.4.113-rc1 review patch.  If anyone has any objections, please let me know.
>
> ------------------
>
>
> commit 025af189fb44250206dd8a32fa4a682392af3301 upstream.
>
> In ttm_write_lock(), the uninterruptible path should call
> __ttm_write_lock() not __ttm_read_lock().  This fixes a vmwgfx hang
> on F23 start up.
>
> syeh: Extracted this from one of Thomas' internal patches.
>
> Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
> Reviewed-by: Sinclair Yeh <syeh@vmware.com>
> Signed-off-by: Zefan Li <lizefan@huawei.com>
> ---
>  drivers/gpu/drm/ttm/ttm_lock.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_lock.c b/drivers/gpu/drm/ttm/ttm_lock.c
> index 075daf4..9934b4d 100644
> --- a/drivers/gpu/drm/ttm/ttm_lock.c
> +++ b/drivers/gpu/drm/ttm/ttm_lock.c
> @@ -180,7 +180,7 @@ int ttm_write_lock(struct ttm_lock *lock, bool interruptible)
>  			spin_unlock(&lock->lock);
>  		}
>  	} else
> -		wait_event(lock->queue, __ttm_read_lock(lock));
> +		wait_event(lock->queue, __ttm_write_lock(lock));
>  
>  	return ret;
>  }