linux-kernel - Re: [PATCH v2 1/3] VFIO: unregister IOMMU notifier on error recovery path

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Message-ID: <1353004289.2233.94.camel@bling.home>
Date:	Thu, 15 Nov 2012 11:31:29 -0700
From:	Alex Williamson <alex.williamson@...hat.com>
To:	Jiang Liu <liuj97@...il.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiang Liu <jiang.liu@...wei.com>,
	Joerg Roedel <joerg.roedel@....com>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org, Hanjun Guo <guohanjun@...wei.com>
Subject: Re: [PATCH v2 1/3] VFIO: unregister IOMMU notifier on error
 recovery path

On Fri, 2012-11-16 at 00:43 +0800, Jiang Liu wrote:
> On error recovery path in function vfio_create_group(), it should
> unregister the IOMMU notifier for the new VFIO group. Otherwise it may
> cause invalid memory access later when handling bus notifications.
> 
> Signed-off-by: Jiang Liu <jiang.liu@...wei.com>
> ---
>  drivers/vfio/vfio.c |   31 +++++++++++++++----------------
>  1 file changed, 15 insertions(+), 16 deletions(-)


Applied all 3, thanks!

Alex

> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> index 17830c9..3359ec2 100644
> --- a/drivers/vfio/vfio.c
> +++ b/drivers/vfio/vfio.c
> @@ -191,6 +191,17 @@ static void vfio_container_put(struct vfio_container *container)
>  	kref_put(&container->kref, vfio_container_release);
>  }
>  
> +static void vfio_group_unlock_and_free(struct vfio_group *group)
> +{
> +	mutex_unlock(&vfio.group_lock);
> +	/*
> +	 * Unregister outside of lock.  A spurious callback is harmless now
> +	 * that the group is no longer in vfio.group_list.
> +	 */
> +	iommu_group_unregister_notifier(group->iommu_group, &group->nb);
> +	kfree(group);
> +}
> +
>  /**
>   * Group objects - create, release, get, put, search
>   */
> @@ -229,8 +240,7 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group)
>  
>  	minor = vfio_alloc_group_minor(group);
>  	if (minor < 0) {
> -		mutex_unlock(&vfio.group_lock);
> -		kfree(group);
> +		vfio_group_unlock_and_free(group);
>  		return ERR_PTR(minor);
>  	}
>  
> @@ -239,8 +249,7 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group)
>  		if (tmp->iommu_group == iommu_group) {
>  			vfio_group_get(tmp);
>  			vfio_free_group_minor(minor);
> -			mutex_unlock(&vfio.group_lock);
> -			kfree(group);
> +			vfio_group_unlock_and_free(group);
>  			return tmp;
>  		}
>  	}
> @@ -249,8 +258,7 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group)
>  			    group, "%d", iommu_group_id(iommu_group));
>  	if (IS_ERR(dev)) {
>  		vfio_free_group_minor(minor);
> -		mutex_unlock(&vfio.group_lock);
> -		kfree(group);
> +		vfio_group_unlock_and_free(group);
>  		return (struct vfio_group *)dev; /* ERR_PTR */
>  	}
>  
> @@ -274,16 +282,7 @@ static void vfio_group_release(struct kref *kref)
>  	device_destroy(vfio.class, MKDEV(MAJOR(vfio.devt), group->minor));
>  	list_del(&group->vfio_next);
>  	vfio_free_group_minor(group->minor);
> -
> -	mutex_unlock(&vfio.group_lock);
> -
> -	/*
> -	 * Unregister outside of lock.  A spurious callback is harmless now
> -	 * that the group is no longer in vfio.group_list.
> -	 */
> -	iommu_group_unregister_notifier(group->iommu_group, &group->nb);
> -
> -	kfree(group);
> +	vfio_group_unlock_and_free(group);
>  }
>  
>  static void vfio_group_put(struct vfio_group *group)



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