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From: Nicolin Chen <nicoleotsuka@gmail.com>
To: thierry.reding@gmail.com, joro@8bytes.org, krzk@kernel.org
Cc: vdumpa@nvidia.com, jonathanh@nvidia.com,
	linux-tegra@vger.kernel.org, iommu@lists.linux-foundation.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH 2/5] iommu/tegra-smmu: Expend mutex protection range
Date: Sat, 26 Sep 2020 01:07:16 -0700	[thread overview]
Message-ID: <20200926080719.6822-3-nicoleotsuka@gmail.com> (raw)
In-Reply-To: <20200926080719.6822-1-nicoleotsuka@gmail.com>

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>
---
 drivers/iommu/tegra-smmu.c | 34 +++++++++++++++++++++-------------
 1 file changed, 21 insertions(+), 13 deletions(-)

diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
index 6335285dc373..b10e02073610 100644
--- a/drivers/iommu/tegra-smmu.c
+++ b/drivers/iommu/tegra-smmu.c
@@ -256,26 +256,19 @@ static int tegra_smmu_alloc_asid(struct tegra_smmu *smmu, unsigned int *idp)
 {
 	unsigned long id;
 
-	mutex_lock(&smmu->lock);
-
 	id = find_first_zero_bit(smmu->asids, smmu->soc->num_asids);
-	if (id >= smmu->soc->num_asids) {
-		mutex_unlock(&smmu->lock);
+	if (id >= smmu->soc->num_asids)
 		return -ENOSPC;
-	}
 
 	set_bit(id, smmu->asids);
 	*idp = id;
 
-	mutex_unlock(&smmu->lock);
 	return 0;
 }
 
 static void tegra_smmu_free_asid(struct tegra_smmu *smmu, unsigned int id)
 {
-	mutex_lock(&smmu->lock);
 	clear_bit(id, smmu->asids);
-	mutex_unlock(&smmu->lock);
 }
 
 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;
 	}
 
 	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;
 	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,
-- 
2.17.1


WARNING: multiple messages have this Message-ID (diff)
From: Nicolin Chen <nicoleotsuka@gmail.com>
To: thierry.reding@gmail.com, joro@8bytes.org, krzk@kernel.org
Cc: linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org,
	iommu@lists.linux-foundation.org, jonathanh@nvidia.com
Subject: [PATCH 2/5] iommu/tegra-smmu: Expend mutex protection range
Date: Sat, 26 Sep 2020 01:07:16 -0700	[thread overview]
Message-ID: <20200926080719.6822-3-nicoleotsuka@gmail.com> (raw)
In-Reply-To: <20200926080719.6822-1-nicoleotsuka@gmail.com>

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>
---
 drivers/iommu/tegra-smmu.c | 34 +++++++++++++++++++++-------------
 1 file changed, 21 insertions(+), 13 deletions(-)

diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
index 6335285dc373..b10e02073610 100644
--- a/drivers/iommu/tegra-smmu.c
+++ b/drivers/iommu/tegra-smmu.c
@@ -256,26 +256,19 @@ static int tegra_smmu_alloc_asid(struct tegra_smmu *smmu, unsigned int *idp)
 {
 	unsigned long id;
 
-	mutex_lock(&smmu->lock);
-
 	id = find_first_zero_bit(smmu->asids, smmu->soc->num_asids);
-	if (id >= smmu->soc->num_asids) {
-		mutex_unlock(&smmu->lock);
+	if (id >= smmu->soc->num_asids)
 		return -ENOSPC;
-	}
 
 	set_bit(id, smmu->asids);
 	*idp = id;
 
-	mutex_unlock(&smmu->lock);
 	return 0;
 }
 
 static void tegra_smmu_free_asid(struct tegra_smmu *smmu, unsigned int id)
 {
-	mutex_lock(&smmu->lock);
 	clear_bit(id, smmu->asids);
-	mutex_unlock(&smmu->lock);
 }
 
 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;
 	}
 
 	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;
 	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,
-- 
2.17.1

_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

  parent reply	other threads:[~2020-09-26  8:12 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-26  8:07 [PATCH 0/5] iommu/tegra-smmu: Adding PCI support and mappings debugfs node Nicolin Chen
2020-09-26  8:07 ` Nicolin Chen
2020-09-26  8:07 ` [PATCH 1/5] iommu/tegra-smmu: Unwrap tegra_smmu_group_get Nicolin Chen
2020-09-26  8:07   ` Nicolin Chen
2020-09-28  7:13   ` Thierry Reding
2020-09-28  7:13     ` Thierry Reding
2020-09-28 19:33     ` Nicolin Chen
2020-09-28 19:33       ` Nicolin Chen
2020-09-26  8:07 ` Nicolin Chen [this message]
2020-09-26  8:07   ` [PATCH 2/5] iommu/tegra-smmu: Expend mutex protection range Nicolin Chen
2020-09-26  8:07 ` [PATCH 3/5] iommu/tegra-smmu: Use iommu_fwspec in .probe_/.attach_device() Nicolin Chen
2020-09-26  8:07   ` Nicolin Chen
2020-09-26 14:48   ` Dmitry Osipenko
2020-09-26 14:48     ` Dmitry Osipenko
2020-09-26 20:42     ` Nicolin Chen
2020-09-26 20:42       ` Nicolin Chen
2020-09-28  7:29     ` Thierry Reding
2020-09-28  7:29       ` Thierry Reding
2020-09-28  7:52   ` Thierry Reding
2020-09-28  7:52     ` Thierry Reding
2020-09-28 22:18     ` Nicolin Chen
2020-09-28 22:18       ` Nicolin Chen
2020-09-29  4:06       ` Dmitry Osipenko
2020-09-29  4:06         ` Dmitry Osipenko
2020-09-29  5:36         ` Nicolin Chen
2020-09-29  5:36           ` Nicolin Chen
2020-09-26  8:07 ` [PATCH 4/5] iommu/tegra-smmu: Add PCI support Nicolin Chen
2020-09-26  8:07   ` Nicolin Chen
2020-09-26 22:18   ` Dmitry Osipenko
2020-09-26 22:18     ` Dmitry Osipenko
2020-09-28 22:31     ` Nicolin Chen
2020-09-28 22:31       ` Nicolin Chen
2020-09-28  7:55   ` Thierry Reding
2020-09-28  7:55     ` Thierry Reding
2020-09-28 22:33     ` Nicolin Chen
2020-09-28 22:33       ` Nicolin Chen
2020-09-26  8:07 ` [PATCH 5/5] iommu/tegra-smmu: Add pagetable mappings to debugfs Nicolin Chen
2020-09-26  8:07   ` Nicolin Chen
2020-09-26 14:48   ` Dmitry Osipenko
2020-09-26 14:48     ` Dmitry Osipenko
2020-09-26 20:47     ` Nicolin Chen
2020-09-26 20:47       ` Nicolin Chen
2020-09-26 21:41       ` Dmitry Osipenko
2020-09-26 21:41         ` Dmitry Osipenko
2020-09-26 21:24   ` Dmitry Osipenko
2020-09-26 21:24     ` Dmitry Osipenko
2020-09-26 21:37     ` Dmitry Osipenko
2020-09-26 21:37       ` Dmitry Osipenko

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