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Message-ID: <CANEJEGv0Bj=iMD=O2jPUc4u918mNQ_CuLvjc2P9ztRrKVKP0iQ@mail.gmail.com>
Date: Fri, 26 Jul 2013 10:16:48 -0700
From: Grant Grundler <grundler@...omium.org>
To: Cho KyongHo <pullip.cho@...sung.com>
Cc: Linux ARM Kernel <linux-arm-kernel@...ts.infradead.org>,
Linux IOMMU <iommu@...ts.linux-foundation.org>,
Linux Kernel <linux-kernel@...r.kernel.org>,
Linux Samsung SOC <linux-samsung-soc@...r.kernel.org>,
Hyunwoong Kim <khw0178.kim@...sung.com>,
Joerg Roedel <joro@...tes.org>,
Kukjin Kim <kgene.kim@...sung.com>,
Prathyush <prathyush.k@...sung.com>,
Rahul Sharma <rahul.sharma@...sung.com>,
Subash Patel <supash.ramaswamy@...aro.org>,
Keyyoung Park <keyyoung.park@...sung.com>,
Grant Grundler <grundler@...omium.org>,
Antonios Motakis <a.motakis@...tualopensystems.com>,
kvmarm@...ts.cs.columbia.edu,
Sachin Kamat <sachin.kamat@...aro.org>
Subject: Re: [PATCH v8 11/12] iommu/exynos: change rwlock to spinlock
On Fri, Jul 26, 2013 at 4:30 AM, Cho KyongHo <pullip.cho@...sung.com> wrote:
> Since acquiring read_lock is not more frequent than write_lock, it is
> not beneficial to use rwlock, this commit changes rwlock to spinlock.
>
> Signed-off-by: Cho KyongHo <pullip.cho@...sung.com>
Reviewed-by: Grant Grundler <grundler@...omium.org>
cheers,
grant
> ---
> drivers/iommu/exynos-iommu.c | 36 ++++++++++++++++++------------------
> 1 files changed, 18 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
> index c62c244..51e5b35 100644
> --- a/drivers/iommu/exynos-iommu.c
> +++ b/drivers/iommu/exynos-iommu.c
> @@ -187,7 +187,7 @@ struct sysmmu_drvdata {
> struct clk *clk;
> struct clk *clk_master;
> int activations;
> - rwlock_t lock;
> + spinlock_t lock;
> struct iommu_domain *domain;
> bool runtime_active;
> unsigned long pgtable;
> @@ -287,7 +287,7 @@ void exynos_sysmmu_set_prefbuf(struct device *dev,
> BUG_ON((base0 + size0) <= base0);
> BUG_ON((size1 > 0) && ((base1 + size1) <= base1));
>
> - read_lock_irqsave(&data->lock, flags);
> + spin_lock_irqsave(&data->lock, flags);
> if (!is_sysmmu_active(data))
> goto finish;
>
> @@ -319,7 +319,7 @@ void exynos_sysmmu_set_prefbuf(struct device *dev,
> }
> clk_disable(data->clk_master);
> finish:
> - read_unlock_irqrestore(&data->lock, flags);
> + spin_unlock_irqrestore(&data->lock, flags);
> }
>
> static void show_fault_information(const char *name,
> @@ -371,7 +371,7 @@ static irqreturn_t exynos_sysmmu_irq(int irq, void *dev_id)
>
> if (client)
> spin_lock(&client->lock);
> - read_lock(&data->lock);
> + spin_lock(&data->lock);
>
> if (i == data->nsfrs) {
> itype = SYSMMU_FAULT_UNKNOWN;
> @@ -402,7 +402,7 @@ static irqreturn_t exynos_sysmmu_irq(int irq, void *dev_id)
> if (itype != SYSMMU_FAULT_UNKNOWN)
> sysmmu_unblock(data->sfrbases[i]);
>
> - read_unlock(&data->lock);
> + spin_unlock(&data->lock);
> if (client)
> spin_unlock(&client->lock);
>
> @@ -429,7 +429,7 @@ static bool __sysmmu_disable(struct sysmmu_drvdata *data)
> bool disabled;
> unsigned long flags;
>
> - write_lock_irqsave(&data->lock, flags);
> + spin_lock_irqsave(&data->lock, flags);
>
> disabled = set_sysmmu_inactive(data);
>
> @@ -446,7 +446,7 @@ static bool __sysmmu_disable(struct sysmmu_drvdata *data)
> data->activations);
> }
>
> - write_unlock_irqrestore(&data->lock, flags);
> + spin_unlock_irqrestore(&data->lock, flags);
>
> return disabled;
> }
> @@ -493,7 +493,7 @@ static int __sysmmu_enable(struct sysmmu_drvdata *data,
> int ret = 0;
> unsigned long flags;
>
> - write_lock_irqsave(&data->lock, flags);
> + spin_lock_irqsave(&data->lock, flags);
> if (set_sysmmu_active(data)) {
> data->pgtable = pgtable;
> data->domain = domain;
> @@ -511,7 +511,7 @@ static int __sysmmu_enable(struct sysmmu_drvdata *data,
> if (WARN_ON(ret < 0))
> set_sysmmu_inactive(data); /* decrement count */
>
> - write_unlock_irqrestore(&data->lock, flags);
> + spin_unlock_irqrestore(&data->lock, flags);
>
> return ret;
> }
> @@ -602,7 +602,7 @@ static void sysmmu_tlb_invalidate_entry(struct device *dev, unsigned long iova)
>
> data = dev_get_drvdata(client->sysmmu[i]);
>
> - read_lock_irqsave(&data->lock, flags);
> + spin_lock_irqsave(&data->lock, flags);
> if (is_sysmmu_active(data) && data->runtime_active) {
> int i;
> clk_enable(data->clk_master);
> @@ -615,7 +615,7 @@ static void sysmmu_tlb_invalidate_entry(struct device *dev, unsigned long iova)
> "disabled. Skipping TLB invalidation @ %#lx\n",
> iova);
> }
> - read_unlock_irqrestore(&data->lock, flags);
> + spin_unlock_irqrestore(&data->lock, flags);
> }
> }
>
> @@ -630,7 +630,7 @@ void exynos_sysmmu_tlb_invalidate(struct device *dev)
>
> data = dev_get_drvdata(client->sysmmu[i]);
>
> - read_lock_irqsave(&data->lock, flags);
> + spin_lock_irqsave(&data->lock, flags);
> if (is_sysmmu_active(data) &&
> data->runtime_active) {
> int i;
> @@ -646,7 +646,7 @@ void exynos_sysmmu_tlb_invalidate(struct device *dev)
> } else {
> dev_dbg(dev, "disabled. Skipping TLB invalidation\n");
> }
> - read_unlock_irqrestore(&data->lock, flags);
> + spin_unlock_irqrestore(&data->lock, flags);
> }
> }
>
> @@ -735,7 +735,7 @@ static int __init exynos_sysmmu_probe(struct platform_device *pdev)
>
> data->runtime_active = !pm_runtime_enabled(dev);
>
> - rwlock_init(&data->lock);
> + spin_lock_init(&data->lock);
> INIT_LIST_HEAD(&data->node);
>
> platform_set_drvdata(pdev, data);
> @@ -749,11 +749,11 @@ static int sysmmu_suspend(struct device *dev)
> {
> struct sysmmu_drvdata *data = dev_get_drvdata(dev);
> unsigned long flags;
> - read_lock_irqsave(&data->lock, flags);
> + spin_lock_irqsave(&data->lock, flags);
> if (is_sysmmu_active(data) &&
> (!pm_runtime_enabled(dev) || data->runtime_active))
> __sysmmu_disable_nocount(data);
> - read_unlock_irqrestore(&data->lock, flags);
> + spin_unlock_irqrestore(&data->lock, flags);
> return 0;
> }
>
> @@ -761,11 +761,11 @@ static int sysmmu_resume(struct device *dev)
> {
> struct sysmmu_drvdata *data = dev_get_drvdata(dev);
> unsigned long flags;
> - read_lock_irqsave(&data->lock, flags);
> + spin_lock_irqsave(&data->lock, flags);
> if (is_sysmmu_active(data) &&
> (!pm_runtime_enabled(dev) || data->runtime_active))
> __sysmmu_enable_nocount(data);
> - read_unlock_irqrestore(&data->lock, flags);
> + spin_unlock_irqrestore(&data->lock, flags);
> return 0;
> }
> #endif
> --
> 1.7.2.5
>
>
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