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From: Nicolin Chen <nicolinc@nvidia.com>
To: Dmitry Osipenko <digetx@gmail.com>
Cc: <thierry.reding@gmail.com>, <joro@8bytes.org>, <will@kernel.org>,
	<vdumpa@nvidia.com>, <jonathanh@nvidia.com>,
	<linux-tegra@vger.kernel.org>, <iommu@lists.linux-foundation.org>,
	<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v8 6/6] iommu/tegra-smmu: Add pagetable mappings to debugfs
Date: Thu, 9 Dec 2021 11:32:54 -0800	[thread overview]
Message-ID: <20211209193253.GB34762@Asurada-Nvidia> (raw)
In-Reply-To: <5713902d-823b-63ca-00c9-aa6c64c1af41@gmail.com>

On Thu, Dec 09, 2021 at 05:47:18PM +0300, Dmitry Osipenko wrote:
> External email: Use caution opening links or attachments
> 
> 
> 09.12.2021 10:38, Nicolin Chen пишет:
> > @@ -545,6 +719,15 @@ static void tegra_smmu_detach_as(struct tegra_smmu *smmu,
> >               if (group->swgrp != swgrp)
> >                       continue;
> >               group->as = NULL;
> > +
> > +             if (smmu->debugfs_mappings) {
> 
> Do we really need this check?
> 
> Looks like all debugfs_create_dir() usages in this driver are incorrect,
> that function never returns NULL. Please fix this.

debugfs_create_dir returns ERR_PTR on failure. So here should be
to check !IS_ERR. Thanks for pointing it out!

> > +                     struct dentry *d;
> 
> The file name is wrong here.
> 
>                         if (group->soc)
>                                 name = group->soc->name;
>                         else
>                                 name = group->swgrp->name;

Yea, I'll add this.

> 
> > +                     d = debugfs_lookup(group->swgrp->name,
> > +                                        smmu->debugfs_mappings);
> > +                     debugfs_remove(d);
> > +             }
> 
> This now looks problematic to me. You created debugfs file when the
> first member of the shared group was attached to AS, now you remove this
> file when any device is detached. The shared debugfs file should be
> refcounted or something.a

Will see how to handle it.

Thanks
Nic

WARNING: multiple messages have this Message-ID (diff)
From: Nicolin Chen via iommu <iommu@lists.linux-foundation.org>
To: Dmitry Osipenko <digetx@gmail.com>
Cc: linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
	jonathanh@nvidia.com, thierry.reding@gmail.com,
	linux-tegra@vger.kernel.org, will@kernel.org
Subject: Re: [PATCH v8 6/6] iommu/tegra-smmu: Add pagetable mappings to debugfs
Date: Thu, 9 Dec 2021 11:32:54 -0800	[thread overview]
Message-ID: <20211209193253.GB34762@Asurada-Nvidia> (raw)
In-Reply-To: <5713902d-823b-63ca-00c9-aa6c64c1af41@gmail.com>

On Thu, Dec 09, 2021 at 05:47:18PM +0300, Dmitry Osipenko wrote:
> External email: Use caution opening links or attachments
> 
> 
> 09.12.2021 10:38, Nicolin Chen пишет:
> > @@ -545,6 +719,15 @@ static void tegra_smmu_detach_as(struct tegra_smmu *smmu,
> >               if (group->swgrp != swgrp)
> >                       continue;
> >               group->as = NULL;
> > +
> > +             if (smmu->debugfs_mappings) {
> 
> Do we really need this check?
> 
> Looks like all debugfs_create_dir() usages in this driver are incorrect,
> that function never returns NULL. Please fix this.

debugfs_create_dir returns ERR_PTR on failure. So here should be
to check !IS_ERR. Thanks for pointing it out!

> > +                     struct dentry *d;
> 
> The file name is wrong here.
> 
>                         if (group->soc)
>                                 name = group->soc->name;
>                         else
>                                 name = group->swgrp->name;

Yea, I'll add this.

> 
> > +                     d = debugfs_lookup(group->swgrp->name,
> > +                                        smmu->debugfs_mappings);
> > +                     debugfs_remove(d);
> > +             }
> 
> This now looks problematic to me. You created debugfs file when the
> first member of the shared group was attached to AS, now you remove this
> file when any device is detached. The shared debugfs file should be
> refcounted or something.a

Will see how to handle it.

Thanks
Nic
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

  reply	other threads:[~2021-12-09 19:33 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-09  7:38 [PATCH v8 0/6] iommu/tegra-smmu: Add pagetable mappings to debugfs Nicolin Chen
2021-12-09  7:38 ` Nicolin Chen via iommu
2021-12-09  7:38 ` [PATCH v8 1/6] iommu/tegra-smmu: Rename struct iommu_group *group to *grp Nicolin Chen
2021-12-09  7:38   ` Nicolin Chen via iommu
2021-12-09  7:38 ` [PATCH v8 2/6] iommu/tegra-smmu: Rename tegra_smmu_find_group to tegra_smmu_find_group_soc Nicolin Chen
2021-12-09  7:38   ` Nicolin Chen via iommu
2021-12-09  7:38 ` [PATCH v8 3/6] iommu/tegra-smmu: Rename struct tegra_smmu_swgroup *group to *swgrp Nicolin Chen
2021-12-09  7:38   ` Nicolin Chen via iommu
2021-12-09  7:38 ` [PATCH v8 4/6] iommu/tegra-smmu: Use swgrp pointer instead of swgroup id Nicolin Chen
2021-12-09  7:38   ` Nicolin Chen via iommu
2021-12-09  7:38 ` [PATCH v8 5/6] iommu/tegra-smmu: Attach as pointer to tegra_smmu_group Nicolin Chen
2021-12-09  7:38   ` Nicolin Chen via iommu
2021-12-09  7:38 ` [PATCH v8 6/6] iommu/tegra-smmu: Add pagetable mappings to debugfs Nicolin Chen
2021-12-09  7:38   ` Nicolin Chen via iommu
2021-12-09 14:47   ` Dmitry Osipenko
2021-12-09 14:47     ` Dmitry Osipenko
2021-12-09 19:32     ` Nicolin Chen [this message]
2021-12-09 19:32       ` Nicolin Chen via iommu
2021-12-09 19:40       ` Dmitry Osipenko
2021-12-09 19:40         ` Dmitry Osipenko
2021-12-09 19:51         ` Nicolin Chen
2021-12-09 19:51           ` Nicolin Chen via iommu
2021-12-09 19:58           ` Dmitry Osipenko
2021-12-09 19:58             ` Dmitry Osipenko
2021-12-09 20:06             ` Nicolin Chen
2021-12-09 20:06               ` Nicolin Chen via iommu
2021-12-09 14:49   ` Dmitry Osipenko
2021-12-09 14:49     ` Dmitry Osipenko
2021-12-09 19:24     ` Nicolin Chen
2021-12-09 19:24       ` Nicolin Chen via iommu
2021-12-09 19:44       ` Dmitry Osipenko
2021-12-09 19:44         ` Dmitry Osipenko
2021-12-09 19:54         ` Nicolin Chen
2021-12-09 19:54           ` Nicolin Chen via iommu
2021-12-09 19:58           ` Dmitry Osipenko
2021-12-09 19:58             ` Dmitry Osipenko
2021-12-09 20:01             ` Nicolin Chen
2021-12-09 20:01               ` Nicolin Chen via iommu
2021-12-09 20:03               ` Dmitry Osipenko
2021-12-09 20:03                 ` Dmitry Osipenko

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