From: Dmitry Osipenko <digetx@gmail.com>
To: Nicolin Chen <nicolinc@nvidia.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 22:58:15 +0300 [thread overview]
Message-ID: <a4002ad9-70d9-22d1-7bcc-ae4f712187c8@gmail.com> (raw)
In-Reply-To: <20211209195128.GA35526@Asurada-Nvidia>
09.12.2021 22:51, Nicolin Chen пишет:
> On Thu, Dec 09, 2021 at 10:40:42PM +0300, Dmitry Osipenko wrote:
>> External email: Use caution opening links or attachments
>>
>>
>> 09.12.2021 22:32, Nicolin Chen пишет:
>>> 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!
>>>
>>
>> All debugfs functions handle IS_ERR(). GregKH removes all such checks
>> all over the kernel. So the check shouldn't be needed at all, please
>> remove it if it's unneeded or prove that it's needed.
>
> debugfs_create_file can handle a NULL parent, but not ERR_PTR one,
> and then it puts the new node under the root. So either passing an
> ERR_PTR parent or creating orphan nodes here doesn't sound good...
>
What makes you say so? Please show the exact source code that will cause
the problem.
The smmu->debugfs_mappings can't ever be NULL and debugfs_create_file
handles the ERR_PTR [1][2].
[1] https://elixir.bootlin.com/linux/latest/source/fs/debugfs/inode.c#L397
[2] https://elixir.bootlin.com/linux/latest/source/fs/debugfs/inode.c#L330
next prev parent reply other threads:[~2021-12-09 19:58 UTC|newest]
Thread overview: 20+ 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 ` [PATCH v8 1/6] iommu/tegra-smmu: Rename struct iommu_group *group to *grp Nicolin Chen
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 ` [PATCH v8 3/6] iommu/tegra-smmu: Rename struct tegra_smmu_swgroup *group to *swgrp Nicolin Chen
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 ` [PATCH v8 5/6] iommu/tegra-smmu: Attach as pointer to tegra_smmu_group Nicolin Chen
2021-12-09 7:38 ` [PATCH v8 6/6] iommu/tegra-smmu: Add pagetable mappings to debugfs Nicolin Chen
2021-12-09 14:47 ` Dmitry Osipenko
2021-12-09 19:32 ` Nicolin Chen
2021-12-09 19:40 ` Dmitry Osipenko
2021-12-09 19:51 ` Nicolin Chen
2021-12-09 19:58 ` Dmitry Osipenko [this message]
2021-12-09 20:06 ` Nicolin Chen
2021-12-09 14:49 ` Dmitry Osipenko
2021-12-09 19:24 ` Nicolin Chen
2021-12-09 19:44 ` Dmitry Osipenko
2021-12-09 19:54 ` Nicolin Chen
2021-12-09 19:58 ` Dmitry Osipenko
2021-12-09 20:01 ` Nicolin Chen
2021-12-09 20:03 ` Dmitry Osipenko
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