linux-kernel - Re: [PATCH v2 3/6] iommu: Same critical region for device release and removal

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Message-ID: <Y++f8UmMK4AvrwBF@nvidia.com>
Date:   Fri, 17 Feb 2023 11:40:33 -0400
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Lu Baolu <baolu.lu@...ux.intel.com>
Cc:     iommu@...ts.linux.dev, Joerg Roedel <joro@...tes.org>,
        Christoph Hellwig <hch@...radead.org>,
        Kevin Tian <kevin.tian@...el.com>,
        Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/6] iommu: Same critical region for device release
 and removal

On Fri, Feb 17, 2023 at 05:47:33PM +0800, Lu Baolu wrote:
> In a non-driver context, it is crucial to ensure the consistency of a
> device's iommu ops. Otherwise, it may result in a situation where a
> device is released but it's iommu ops are still used.
> 
> Put the ops->release_device and __iommu_group_remove_device() in a some
> group->mutext critical region, so that, as long as group->mutex is held
> and the device is in its group's device list, its iommu ops are always
> consistent.
> 
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> ---
>  drivers/iommu/iommu.c | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 6247883991e2..093692308b80 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -101,6 +101,10 @@ static int iommu_create_device_direct_mappings(struct iommu_group *group,
>  static struct iommu_group *iommu_group_get_for_dev(struct device *dev);
>  static ssize_t iommu_group_store_type(struct iommu_group *group,
>  				      const char *buf, size_t count);
> +static struct group_device *
> +__iommu_group_remove_device(struct iommu_group *group, struct device *dev);
> +static void __iommu_group_release_device(struct iommu_group *group,
> +					 struct group_device *grp_dev);

Seems like a hunk is missing from this patch?

Jason