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From: Joerg Roedel <joro@8bytes.org>
To: Lu Baolu <baolu.lu@linux.intel.com>
Cc: Kevin Tian <kevin.tian@intel.com>,
	Ashok Raj <ashok.raj@intel.com>, David Airlie <airlied@linux.ie>,
	Robin Murphy <robin.murphy@arm.com>,
	iommu@lists.linux-foundation.org,
	Jonathan Hunter <jonathanh@nvidia.com>,
	Christoph Hellwig <hch@infradead.org>,
	Alex Williamson <alex.williamson@redhat.com>,
	Thierry Reding <thierry.reding@gmail.com>,
	Ben Skeggs <bskeggs@redhat.com>, Jason Gunthorpe <jgg@nvidia.com>,
	Daniel Vetter <daniel@ffwll.ch>, Will Deacon <will@kernel.org>,
	Christoph Hellwig <hch@lst.de>,
	linux-kernel@vger.kernel.org,
	Jacob jun Pan <jacob.jun.pan@intel.com>
Subject: Re: [PATCH v3 07/10] iommu: Use right way to retrieve iommu_ops
Date: Mon, 14 Feb 2022 13:49:48 +0100	[thread overview]
Message-ID: <YgpP7AhY5hd/DX/C@8bytes.org> (raw)
In-Reply-To: <20220214015538.2828933-8-baolu.lu@linux.intel.com>

On Mon, Feb 14, 2022 at 09:55:35AM +0800, Lu Baolu wrote:
> +static inline const struct iommu_ops *dev_iommu_ops(struct device *dev)
> +{
> +	/*
> +	 * Assume that valid ops must be installed if iommu_probe_device()
> +	 * has succeeded. The device ops are essentially for internal use
> +	 * within the IOMMU subsystem itself, so we should be able to trust
> +	 * ourselves not to misuse the helper.
> +	 */
> +	WARN_ON(!dev || !dev->iommu || !dev->iommu->iommu_dev ||
> +		!dev->iommu->iommu_dev->ops);

There is no need for this WARN_ON, the code will oops anyway when one of
the pointers checked here is NULL.

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WARNING: multiple messages have this Message-ID (diff)
From: Joerg Roedel <joro@8bytes.org>
To: Lu Baolu <baolu.lu@linux.intel.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>,
	Christoph Hellwig <hch@infradead.org>,
	Ben Skeggs <bskeggs@redhat.com>,
	Kevin Tian <kevin.tian@intel.com>,
	Ashok Raj <ashok.raj@intel.com>, Will Deacon <will@kernel.org>,
	Robin Murphy <robin.murphy@arm.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Eric Auger <eric.auger@redhat.com>, Liu Yi L <yi.l.liu@intel.com>,
	Jacob jun Pan <jacob.jun.pan@intel.com>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
	Thierry Reding <thierry.reding@gmail.com>,
	Jonathan Hunter <jonathanh@nvidia.com>,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v3 07/10] iommu: Use right way to retrieve iommu_ops
Date: Mon, 14 Feb 2022 13:49:48 +0100	[thread overview]
Message-ID: <YgpP7AhY5hd/DX/C@8bytes.org> (raw)
In-Reply-To: <20220214015538.2828933-8-baolu.lu@linux.intel.com>

On Mon, Feb 14, 2022 at 09:55:35AM +0800, Lu Baolu wrote:
> +static inline const struct iommu_ops *dev_iommu_ops(struct device *dev)
> +{
> +	/*
> +	 * Assume that valid ops must be installed if iommu_probe_device()
> +	 * has succeeded. The device ops are essentially for internal use
> +	 * within the IOMMU subsystem itself, so we should be able to trust
> +	 * ourselves not to misuse the helper.
> +	 */
> +	WARN_ON(!dev || !dev->iommu || !dev->iommu->iommu_dev ||
> +		!dev->iommu->iommu_dev->ops);

There is no need for this WARN_ON, the code will oops anyway when one of
the pointers checked here is NULL.


  reply	other threads:[~2022-02-14 12:49 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-14  1:55 [PATCH v3 00/10] iommu cleanup and refactoring Lu Baolu
2022-02-14  1:55 ` Lu Baolu
2022-02-14  1:55 ` [PATCH v3 01/10] iommu/vt-d: Remove guest pasid related callbacks Lu Baolu
2022-02-14  1:55   ` Lu Baolu
2022-02-14  1:55 ` [PATCH v3 02/10] iommu: Remove guest pasid related interfaces and definitions Lu Baolu
2022-02-14  1:55   ` Lu Baolu
2022-02-14  1:55 ` [PATCH v3 03/10] iommu/vt-d: Remove aux-domain related callbacks Lu Baolu
2022-02-14  1:55   ` Lu Baolu
2022-02-14  1:55 ` [PATCH v3 04/10] iommu: Remove aux-domain related interfaces and iommu_ops Lu Baolu
2022-02-14  1:55   ` Lu Baolu
2022-02-14  1:55 ` [PATCH v3 05/10] iommu: Remove apply_resv_region Lu Baolu
2022-02-14  1:55   ` Lu Baolu
2022-02-14  1:55 ` [PATCH v3 06/10] drm/nouveau/device: Get right pgsize_bitmap of iommu_domain Lu Baolu
2022-02-14  1:55   ` Lu Baolu
2022-02-14 12:52   ` Joerg Roedel
2022-02-14 12:52     ` Joerg Roedel
2022-02-15  2:08     ` Lu Baolu
2022-02-15  2:08       ` Lu Baolu
2022-02-14  1:55 ` [PATCH v3 07/10] iommu: Use right way to retrieve iommu_ops Lu Baolu
2022-02-14  1:55   ` Lu Baolu
2022-02-14 12:49   ` Joerg Roedel [this message]
2022-02-14 12:49     ` Joerg Roedel
2022-02-15  1:46     ` Lu Baolu
2022-02-15  1:46       ` Lu Baolu
2022-02-15  2:01       ` Lu Baolu
2022-02-15  2:01         ` Lu Baolu
2022-02-14  1:55 ` [PATCH v3 08/10] iommu: Remove unused argument in is_attach_deferred Lu Baolu
2022-02-14  1:55   ` Lu Baolu
2022-02-14  1:55 ` [PATCH v3 09/10] iommu: Use dev_iommu_ops() helper Lu Baolu
2022-02-14  1:55   ` Lu Baolu
2022-02-14 13:26   ` Jason Gunthorpe via iommu
2022-02-14 13:26     ` Jason Gunthorpe
2022-02-15  1:39     ` Lu Baolu
2022-02-15  1:39       ` Lu Baolu
2022-02-14  1:55 ` [PATCH v3 10/10] iommu: Split struct iommu_ops Lu Baolu
2022-02-14  1:55   ` Lu Baolu
2022-02-14 14:14 ` [PATCH v3 00/10] iommu cleanup and refactoring Joerg Roedel
2022-02-14 14:14   ` Joerg Roedel
2022-02-15  2:05   ` Lu Baolu
2022-02-15  2:05     ` Lu Baolu
2022-02-15  9:17     ` Joerg Roedel
2022-02-15  9:17       ` Joerg Roedel
2022-02-16  2:56       ` Lu Baolu
2022-02-16  2:56         ` Lu Baolu

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