linux-kernel - Re: [PATCH 8/9] dmaengine: idxd: Fix freeing the allocated ida too late

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Message-ID: <7972e017-ec4a-4fe4-a11f-bc0a1ff9b6f7@intel.com>
Date: Wed, 6 Aug 2025 10:27:38 -0700
From: Dave Jiang <dave.jiang@...el.com>
To: Vinicius Costa Gomes <vinicius.gomes@...el.com>,
 Vinod Koul <vkoul@...nel.org>, Dan Williams <dan.j.williams@...el.com>,
 Fenghua Yu <fenghuay@...dia.com>
Cc: dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 8/9] dmaengine: idxd: Fix freeing the allocated ida too
 late



On 8/4/25 6:27 PM, Vinicius Costa Gomes wrote:
> It can happen that when the cdev .release() is called, the driver
> already called ida_destroy(). Move ida_free() to the _del() path.
> 
> We see with DEBUG_KOBJECT_RELEASE enabled and forcing an early PCI
> unbind.
> 
> Fixes: 04922b7445a1 ("dmaengine: idxd: fix cdev setup and free device lifetime issues")
> Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@...el.com>

Reviewed-by: Dave Jiang <dave.jiang@...el.com>
> ---
>  drivers/dma/idxd/cdev.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/dma/idxd/cdev.c b/drivers/dma/idxd/cdev.c
> index 7e4715f927732702416d917f34ab0a83f575d533..4105688cf3f060704b851ee17467c135c170326e 100644
> --- a/drivers/dma/idxd/cdev.c
> +++ b/drivers/dma/idxd/cdev.c
> @@ -158,11 +158,7 @@ static const struct device_type idxd_cdev_file_type = {
>  static void idxd_cdev_dev_release(struct device *dev)
>  {
>  	struct idxd_cdev *idxd_cdev = dev_to_cdev(dev);
> -	struct idxd_cdev_context *cdev_ctx;
> -	struct idxd_wq *wq = idxd_cdev->wq;
>  
> -	cdev_ctx = &ictx[wq->idxd->data->type];
> -	ida_free(&cdev_ctx->minor_ida, idxd_cdev->minor);
>  	kfree(idxd_cdev);
>  }
>  
> @@ -582,11 +578,15 @@ int idxd_wq_add_cdev(struct idxd_wq *wq)
>  
>  void idxd_wq_del_cdev(struct idxd_wq *wq)
>  {
> +	struct idxd_cdev_context *cdev_ctx;
>  	struct idxd_cdev *idxd_cdev;
>  
>  	idxd_cdev = wq->idxd_cdev;
>  	wq->idxd_cdev = NULL;
>  	cdev_device_del(&idxd_cdev->cdev, cdev_dev(idxd_cdev));
> +
> +	cdev_ctx = &ictx[wq->idxd->data->type];
> +	ida_free(&cdev_ctx->minor_ida, idxd_cdev->minor);
>  	put_device(cdev_dev(idxd_cdev));
>  }
>  
>