From: Dmitry Osipenko <digetx@gmail.com>
To: Nicolin Chen <nicoleotsuka@gmail.com>
Cc: thierry.reding@gmail.com, joro@8bytes.org, krzk@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 v2 2/3] iommu/tegra-smmu: Rework .probe_device and .attach_dev
Date: Wed, 30 Sep 2020 09:33:36 +0300 [thread overview]
Message-ID: <9a1ec0bf-3020-2045-229c-a350c9c9fc2e@gmail.com> (raw)
In-Reply-To: <20200930061351.GA16460@Asurada-Nvidia>
30.09.2020 09:13, Nicolin Chen пишет:
> On Wed, Sep 30, 2020 at 09:10:38AM +0300, Dmitry Osipenko wrote:
>> 30.09.2020 08:49, Nicolin Chen пишет:
>>> On Wed, Sep 30, 2020 at 08:11:52AM +0300, Dmitry Osipenko wrote:
>>>> 30.09.2020 03:30, Nicolin Chen пишет:
>>>>> + /* An invalid mc pointer means mc and smmu drivers are not ready */
>>>>> + if (IS_ERR_OR_NULL(mc))
>>>>
>>>> tegra_get_memory_controller() doesn't return NULL.
>>>
>>> Well, I don't want to assume that it'd do that forever, and the
>>> NULL check of IS_ERR_OR_NULL is marked "unlikely" so it doesn't
>>> hurt to have.
>>>
>>
>> I don't see any reasons why it won't do that forever.
>>
>> Secondly, public function can't be changed randomly without updating all
>> the callers.
>>
>> Hence there is no need to handle cases that can't ever happen and it
>> hurts readability of the code + original error code is missed.
>
> I don't quite understand why an extra "_OR_NULL" would hurt
> readability....but I'd take a step back and use IS_ERR().
>
The tegra_get_memory_controller() doesn't return NULL, hence the
NULL-check is misleading.
If I was reading that code for the first time and notice such a thing,
then instantly I'd have a much lower credibility to the whole code.
next prev parent reply other threads:[~2020-09-30 6:33 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-30 0:30 [PATCH v2 0/3] iommu/tegra-smmu: Add PCI support Nicolin Chen
2020-09-30 0:30 ` [PATCH v2 1/3] memory: tegra: Add helper function tegra_get_memory_controller Nicolin Chen
2020-09-30 5:12 ` Dmitry Osipenko
2020-09-30 5:44 ` Nicolin Chen
2020-09-30 6:32 ` Dmitry Osipenko
2020-09-30 6:38 ` Nicolin Chen
2020-09-30 7:31 ` Dmitry Osipenko
2020-09-30 7:21 ` Krzysztof Kozlowski
2020-09-30 7:25 ` Nicolin Chen
2020-09-30 7:50 ` Krzysztof Kozlowski
2020-09-30 0:30 ` [PATCH v2 2/3] iommu/tegra-smmu: Rework .probe_device and .attach_dev Nicolin Chen
2020-09-30 5:10 ` Dmitry Osipenko
2020-09-30 5:20 ` Dmitry Osipenko
2020-09-30 5:50 ` Nicolin Chen
2020-09-30 6:34 ` Nicolin Chen
2020-09-30 5:11 ` Dmitry Osipenko
2020-09-30 5:49 ` Nicolin Chen
2020-09-30 6:10 ` Dmitry Osipenko
2020-09-30 6:13 ` Nicolin Chen
2020-09-30 6:33 ` Dmitry Osipenko [this message]
2020-09-30 5:24 ` Dmitry Osipenko
2020-09-30 5:39 ` Nicolin Chen
2020-09-30 5:48 ` Dmitry Osipenko
2020-09-30 5:39 ` Dmitry Osipenko
2020-09-30 5:41 ` Nicolin Chen
2020-09-30 5:59 ` Dmitry Osipenko
2020-09-30 6:19 ` Nicolin Chen
2020-09-30 0:30 ` [PATCH v2 3/3] iommu/tegra-smmu: Add PCI support Nicolin Chen
2020-09-30 5:10 ` Dmitry Osipenko
2020-09-30 5:28 ` Nicolin Chen
2020-09-30 5:10 ` Dmitry Osipenko
2020-09-30 5:29 ` Nicolin Chen
2020-09-30 5:58 ` Dmitry Osipenko
2020-09-30 7:16 ` Nicolin Chen
2020-09-30 5:10 ` Dmitry Osipenko
2020-09-30 5:34 ` Nicolin Chen
2020-09-30 6:01 ` Dmitry Osipenko
2020-09-30 7:12 ` Nicolin Chen
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