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iommu/tegra-smmu: Expand mutex protection range
This is used to protect potential race condition at use_count. since probes of client drivers, calling attach_dev(), may run concurrently. Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com> Tested-by: Dmitry Osipenko <digetx@gmail.com> Reviewed-by: Dmitry Osipenko <digetx@gmail.com> Acked-by: Thierry Reding <treding@nvidia.com> Link: https://lore.kernel.org/r/20201125101013.14953-3-nicoleotsuka@gmail.com Signed-off-by: Will Deacon <will@kernel.org>
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1 changed files with 21 additions and 13 deletions
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@ -256,26 +256,19 @@ static int tegra_smmu_alloc_asid(struct tegra_smmu *smmu, unsigned int *idp)
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{
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unsigned long id;
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mutex_lock(&smmu->lock);
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id = find_first_zero_bit(smmu->asids, smmu->soc->num_asids);
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if (id >= smmu->soc->num_asids) {
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mutex_unlock(&smmu->lock);
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if (id >= smmu->soc->num_asids)
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return -ENOSPC;
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}
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set_bit(id, smmu->asids);
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*idp = id;
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mutex_unlock(&smmu->lock);
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return 0;
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}
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static void tegra_smmu_free_asid(struct tegra_smmu *smmu, unsigned int id)
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{
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mutex_lock(&smmu->lock);
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clear_bit(id, smmu->asids);
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mutex_unlock(&smmu->lock);
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}
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static bool tegra_smmu_capable(enum iommu_cap cap)
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@ -420,17 +413,21 @@ static int tegra_smmu_as_prepare(struct tegra_smmu *smmu,
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struct tegra_smmu_as *as)
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{
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u32 value;
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int err;
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int err = 0;
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mutex_lock(&smmu->lock);
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if (as->use_count > 0) {
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as->use_count++;
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return 0;
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goto unlock;
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}
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as->pd_dma = dma_map_page(smmu->dev, as->pd, 0, SMMU_SIZE_PD,
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DMA_TO_DEVICE);
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if (dma_mapping_error(smmu->dev, as->pd_dma))
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return -ENOMEM;
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if (dma_mapping_error(smmu->dev, as->pd_dma)) {
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err = -ENOMEM;
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goto unlock;
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}
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/* We can't handle 64-bit DMA addresses */
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if (!smmu_dma_addr_valid(smmu, as->pd_dma)) {
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@ -453,24 +450,35 @@ static int tegra_smmu_as_prepare(struct tegra_smmu *smmu,
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as->smmu = smmu;
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as->use_count++;
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mutex_unlock(&smmu->lock);
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return 0;
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err_unmap:
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dma_unmap_page(smmu->dev, as->pd_dma, SMMU_SIZE_PD, DMA_TO_DEVICE);
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unlock:
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mutex_unlock(&smmu->lock);
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return err;
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}
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static void tegra_smmu_as_unprepare(struct tegra_smmu *smmu,
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struct tegra_smmu_as *as)
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{
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if (--as->use_count > 0)
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mutex_lock(&smmu->lock);
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if (--as->use_count > 0) {
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mutex_unlock(&smmu->lock);
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return;
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}
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tegra_smmu_free_asid(smmu, as->id);
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dma_unmap_page(smmu->dev, as->pd_dma, SMMU_SIZE_PD, DMA_TO_DEVICE);
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as->smmu = NULL;
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mutex_unlock(&smmu->lock);
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}
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static int tegra_smmu_attach_dev(struct iommu_domain *domain,
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