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[109.252.170.211]) by smtp.googlemail.com with ESMTPSA id 80sm226170lff.61.2020.09.30.08.22.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 30 Sep 2020 08:22:38 -0700 (PDT) Subject: Re: [PATCH v3 1/3] memory: tegra: Add devm_tegra_get_memory_controller() To: Krzysztof Kozlowski Cc: Nicolin Chen , thierry.reding@gmail.com, joro@8bytes.org, vdumpa@nvidia.com, jonathanh@nvidia.com, linux-tegra@vger.kernel.org, iommu@lists.linux-foundation.org, "linux-kernel@vger.kernel.org" References: <20200930084258.25493-1-nicoleotsuka@gmail.com> <20200930084258.25493-2-nicoleotsuka@gmail.com> From: Dmitry Osipenko Message-ID: <257958e0-8359-4296-9653-ba821b39d813@gmail.com> Date: Wed, 30 Sep 2020 18:22:37 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-tegra@vger.kernel.org 30.09.2020 17:45, Krzysztof Kozlowski пишет: > On Wed, 30 Sep 2020 at 16:41, Dmitry Osipenko wrote: >> >> ... >>> +struct tegra_mc *devm_tegra_get_memory_controller(struct device *dev) >>> +{ >>> + struct platform_device *pdev; >>> + struct device_node *np; >>> + struct tegra_mc *mc; >>> + int err; >>> + >>> + np = of_find_matching_node_and_match(NULL, tegra_mc_of_match, NULL); >>> + if (!np) >>> + return ERR_PTR(-ENOENT); >>> + >>> + pdev = of_find_device_by_node(np); >>> + of_node_put(np); >>> + if (!pdev) >>> + return ERR_PTR(-ENODEV); >>> + >>> + mc = platform_get_drvdata(pdev); >>> + if (!mc) { >>> + put_device(mc->dev); >> >> This should be put_device(&pdev->dev). Please always be careful while >> copying someones else code :) > > Good catch. I guess devm_add_action_or_reset() would also work... or > running Smatch on new code. Smatch should point it out. The devm_add_action_or_reset() shouldn't help much in this particular case because it's too early for the devm_add_action here. Having an explicit put_device() in all error code paths also helps with improving readability of the code a tad, IMO. Smatch indeed should catch this bug, but Smatch usually isn't a part of the developers workflow. More often Smatch is a part of maintainers workflow, hence such problems usually are getting caught before patches are applied.