linux-kernel - [PATCH v5 5/7] iommu/exynos: Rework and fix internal locking

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Date:   Thu, 20 Oct 2016 09:22:51 +0200
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        iommu@...ts.linux-foundation.org, linux-samsung-soc@...r.kernel.org
Cc:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Joerg Roedel <joro@...tes.org>,
        Inki Dae <inki.dae@...sung.com>, Kukjin Kim <kgene@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Mark Brown <broonie@...nel.org>,
        "Luis R. Rodriguez" <mcgrof@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        Lukas Wunner <lukas@...ner.de>,
        Kevin Hilman <khilman@...nel.org>,
        Tobias Jakobi <tjakobi@...h.uni-bielefeld.de>,
        Tomasz Figa <tomasz.figa@...il.com>
Subject: [PATCH v5 5/7] iommu/exynos: Rework and fix internal locking

This patch reworks locking in the exynos_iommu_attach/detach_device
functions to ensure that all entries of the sysmmu_drvdata and
exynos_iommu_owner structure are updated under the respective spinlocks,
while runtime pm functions are called without any spinlocks held.

Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
---
 drivers/iommu/exynos-iommu.c | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
index 28e570b53672..a959443e6f33 100644
--- a/drivers/iommu/exynos-iommu.c
+++ b/drivers/iommu/exynos-iommu.c
@@ -731,10 +731,12 @@ static void exynos_iommu_domain_free(struct iommu_domain *iommu_domain)
 	spin_lock_irqsave(&domain->lock, flags);
 
 	list_for_each_entry_safe(data, next, &domain->clients, domain_node) {
+		spin_lock(&data->lock);
 		__sysmmu_disable(data);
 		data->pgtable = 0;
 		data->domain = NULL;
 		list_del_init(&data->domain_node);
+		spin_unlock(&data->lock);
 	}
 
 	spin_unlock_irqrestore(&domain->lock, flags);
@@ -772,17 +774,22 @@ static void exynos_iommu_detach_device(struct iommu_domain *iommu_domain,
 	if (!has_sysmmu(dev) || owner->domain != iommu_domain)
 		return;
 
+	list_for_each_entry(data, &owner->controllers, owner_node) {
+		__sysmmu_disable(data);
+		pm_runtime_put(data->sysmmu);
+	}
+
 	spin_lock_irqsave(&domain->lock, flags);
 	list_for_each_entry_safe(data, next, &domain->clients, domain_node) {
-		__sysmmu_disable(data);
+		spin_lock(&data->lock);
 		data->pgtable = 0;
 		data->domain = NULL;
 		list_del_init(&data->domain_node);
-		pm_runtime_put(data->sysmmu);
+		spin_unlock(&data->lock);
 	}
+	owner->domain = NULL;
 	spin_unlock_irqrestore(&domain->lock, flags);
 
-	owner->domain = NULL;
 
 	dev_dbg(dev, "%s: Detached IOMMU with pgtable %pa\n", __func__,
 		&pagetable);
@@ -803,18 +810,22 @@ static int exynos_iommu_attach_device(struct iommu_domain *iommu_domain,
 	if (owner->domain)
 		exynos_iommu_detach_device(owner->domain, dev);
 
+	spin_lock_irqsave(&domain->lock, flags);
 	list_for_each_entry(data, &owner->controllers, owner_node) {
+		spin_lock(&data->lock);
 		data->pgtable = pagetable;
 		data->domain = domain;
+		list_add_tail(&data->domain_node, &domain->clients);
+		spin_unlock(&data->lock);
+	}
+	owner->domain = iommu_domain;
+	spin_unlock_irqrestore(&domain->lock, flags);
+
+	list_for_each_entry(data, &owner->controllers, owner_node) {
 		pm_runtime_get_sync(data->sysmmu);
 		__sysmmu_enable(data);
-
-		spin_lock_irqsave(&domain->lock, flags);
-		list_add_tail(&data->domain_node, &domain->clients);
-		spin_unlock_irqrestore(&domain->lock, flags);
 	}
 
-	owner->domain = iommu_domain;
 	dev_dbg(dev, "%s: Attached IOMMU with pgtable %pa\n", __func__,
 		&pagetable);
 
-- 
1.9.1