From: Dmitry Osipenko <digetx@gmail.com>
To: Nicolin Chen <nicoleotsuka@gmail.com>,
thierry.reding@gmail.com, joro@8bytes.org
Cc: vdumpa@nvidia.com, jonathanh@nvidia.com,
linux-tegra@vger.kernel.org, iommu@lists.linux-foundation.org,
linux-kernel@vger.kernel.org, hch@infradead.org
Subject: Re: [PATCH v4 1/2] iommu/tegra-smmu: Unwrap tegra_smmu_group_get
Date: Tue, 29 Sep 2020 20:41:49 +0300 [thread overview]
Message-ID: <35d789ae-7deb-7f8c-0556-98fe73f5999f@gmail.com> (raw)
In-Reply-To: <20200929061325.10197-2-nicoleotsuka@gmail.com>
29.09.2020 09:13, Nicolin Chen пишет:
> The tegra_smmu_group_get was added to group devices in different
> SWGROUPs and it'd return a NULL group pointer upon a mismatch at
> tegra_smmu_find_group(), so for most of clients/devices, it very
> likely would mismatch and need a fallback generic_device_group().
>
> But now tegra_smmu_group_get handles devices in same SWGROUP too,
> which means that it would allocate a group for every new SWGROUP
> or would directly return an existing one upon matching a SWGROUP,
> i.e. any device will go through this function.
>
> So possibility of having a NULL group pointer in device_group()
> is upon failure of either devm_kzalloc() or iommu_group_alloc().
> In either case, calling generic_device_group() no longer makes a
> sense. Especially for devm_kzalloc() failing case, it'd cause a
> problem if it fails at devm_kzalloc() yet succeeds at a fallback
> generic_device_group(), because it does not create a group->list
> for other devices to match.
>
> This patch simply unwraps the function to clean it up.
>
> Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
> ---
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
next prev parent reply other threads:[~2020-09-29 17:41 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-29 6:13 [PATCH v4 0/2] iommu/tegra-smmu: Two followup changes Nicolin Chen
2020-09-29 6:13 ` [PATCH v4 1/2] iommu/tegra-smmu: Unwrap tegra_smmu_group_get Nicolin Chen
2020-09-29 17:41 ` Dmitry Osipenko [this message]
2020-10-03 14:27 ` Dmitry Osipenko
2020-10-08 9:55 ` Thierry Reding
2020-09-29 6:13 ` [PATCH v4 2/2] iommu/tegra-smmu: Expand mutex protection range Nicolin Chen
2020-09-29 17:42 ` Dmitry Osipenko
2020-09-30 0:31 ` Nicolin Chen
2020-10-03 14:28 ` Dmitry Osipenko
2020-10-08 9:56 ` Thierry Reding
2020-11-07 8:35 ` [PATCH v4 0/2] iommu/tegra-smmu: Two followup changes Nicolin Chen
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