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[109.252.170.211]) by smtp.googlemail.com with ESMTPSA id x25sm2990589lfe.284.2020.09.28.17.17.58 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 28 Sep 2020 17:17:59 -0700 (PDT) Subject: Re: [PATCH v2 2/2] iommu/tegra-smmu: Expend mutex protection range To: Nicolin Chen , 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 References: <20200928235901.28337-1-nicoleotsuka@gmail.com> <20200928235901.28337-3-nicoleotsuka@gmail.com> From: Dmitry Osipenko Message-ID: <692b51fa-7a3e-dee7-b628-7cb2d2dc188d@gmail.com> Date: Tue, 29 Sep 2020 03:17:58 +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: <20200928235901.28337-3-nicoleotsuka@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ... > static bool tegra_smmu_capable(enum iommu_cap cap) > @@ -420,17 +413,21 @@ static int tegra_smmu_as_prepare(struct tegra_smmu *smmu, > struct tegra_smmu_as *as) > { > u32 value; > - int err; > + int err = 0; > + > + mutex_lock(&smmu->lock); > > if (as->use_count > 0) { > as->use_count++; > - return 0; > + goto err_unlock; This looks a bit odd because it's not a error condition. Perhaps should be better to "goto bump_usecount"? Or make it similar to tegra_smmu_as_unprepare()? > } > > as->pd_dma = dma_map_page(smmu->dev, as->pd, 0, SMMU_SIZE_PD, > DMA_TO_DEVICE); > - if (dma_mapping_error(smmu->dev, as->pd_dma)) > - return -ENOMEM; > + if (dma_mapping_error(smmu->dev, as->pd_dma)) { > + err = -ENOMEM; > + goto err_unlock; > + } > > /* We can't handle 64-bit DMA addresses */ > if (!smmu_dma_addr_valid(smmu, as->pd_dma)) { > @@ -453,24 +450,35 @@ static int tegra_smmu_as_prepare(struct tegra_smmu *smmu, > as->smmu = smmu; bump_usecount: > as->use_count++; > > + mutex_unlock(&smmu->lock); > + > return 0; > > err_unmap: > dma_unmap_page(smmu->dev, as->pd_dma, SMMU_SIZE_PD, DMA_TO_DEVICE); > +err_unlock: > + mutex_unlock(&smmu->lock); > + > return err; > } > > static void tegra_smmu_as_unprepare(struct tegra_smmu *smmu, > struct tegra_smmu_as *as) > { > - if (--as->use_count > 0) > + mutex_lock(&smmu->lock); > + > + if (--as->use_count > 0) { > + mutex_unlock(&smmu->lock); > return; > + } > > tegra_smmu_free_asid(smmu, as->id); > > dma_unmap_page(smmu->dev, as->pd_dma, SMMU_SIZE_PD, DMA_TO_DEVICE); > > as->smmu = NULL; > + > + mutex_unlock(&smmu->lock); > } > > static int tegra_smmu_attach_dev(struct iommu_domain *domain, >