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Message-id: <13890783.WKk2X4EVm4@amdc1032>
Date: Fri, 12 Jul 2013 17:30:33 +0200
From: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
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>
Subject: Re: [PATCH v7 5/9] iommu/exynos: change rwlock to spinlock
Hi,
On Friday, July 05, 2013 09:29:26 PM Cho KyongHo 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.
This change is not of a "fix type" and is not required to make the driver
work so it would probably be best to move it to the end of a patch series
(IOW just making it the last patch in the series).
Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics
> Signed-off-by: Cho KyongHo <pullip.cho@...sung.com>
> ---
> drivers/iommu/exynos-iommu.c | 32 ++++++++++++++++----------------
> 1 files changed, 16 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
> index 390f8b7..6793661 100644
> --- a/drivers/iommu/exynos-iommu.c
> +++ b/drivers/iommu/exynos-iommu.c
> @@ -175,7 +175,7 @@ struct sysmmu_drvdata {
> void __iomem **sfrbases;
> struct clk *clk[2];
> int activations;
> - rwlock_t lock;
> + spinlock_t lock;
> struct iommu_domain *domain;
> sysmmu_fault_handler_t fault_handler;
> unsigned long pgtable;
> @@ -259,7 +259,7 @@ 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;
>
> @@ -289,7 +289,7 @@ void exynos_sysmmu_set_prefbuf(struct device *dev,
> }
> }
> finish:
> - read_unlock_irqrestore(&data->lock, flags);
> + spin_unlock_irqrestore(&data->lock, flags);
> }
>
> static void __set_fault_handler(struct sysmmu_drvdata *data,
> @@ -297,9 +297,9 @@ static void __set_fault_handler(struct sysmmu_drvdata *data,
> {
> unsigned long flags;
>
> - write_lock_irqsave(&data->lock, flags);
> + spin_lock_irqsave(&data->lock, flags);
> data->fault_handler = handler;
> - write_unlock_irqrestore(&data->lock, flags);
> + spin_unlock_irqrestore(&data->lock, flags);
> }
>
> void exynos_sysmmu_set_fault_handler(struct device *dev,
> @@ -347,7 +347,7 @@ static irqreturn_t exynos_sysmmu_irq(int irq, void *dev_id)
>
> int i, ret = -ENOSYS;
>
> - read_lock(&data->lock);
> + spin_lock(&data->lock);
>
> WARN_ON(!is_sysmmu_active(data));
>
> @@ -391,7 +391,7 @@ 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);
>
> return IRQ_HANDLED;
> }
> @@ -402,7 +402,7 @@ static bool __exynos_sysmmu_disable(struct sysmmu_drvdata *data)
> bool disabled = false;
> int i;
>
> - write_lock_irqsave(&data->lock, flags);
> + spin_lock_irqsave(&data->lock, flags);
>
> if (!set_sysmmu_inactive(data))
> goto finish;
> @@ -419,7 +419,7 @@ static bool __exynos_sysmmu_disable(struct sysmmu_drvdata *data)
> data->pgtable = 0;
> data->domain = NULL;
> finish:
> - write_unlock_irqrestore(&data->lock, flags);
> + spin_unlock_irqrestore(&data->lock, flags);
>
> if (disabled)
> dev_dbg(data->sysmmu, "(%s) Disabled\n", data->dbgname);
> @@ -442,7 +442,7 @@ static int __exynos_sysmmu_enable(struct sysmmu_drvdata *data,
> int i, ret = 0;
> unsigned long flags;
>
> - write_lock_irqsave(&data->lock, flags);
> + spin_lock_irqsave(&data->lock, flags);
>
> if (!set_sysmmu_active(data)) {
> if (WARN_ON(pgtable != data->pgtable)) {
> @@ -481,7 +481,7 @@ static int __exynos_sysmmu_enable(struct sysmmu_drvdata *data,
>
> dev_dbg(data->sysmmu, "(%s) Enabled\n", data->dbgname);
> finish:
> - write_unlock_irqrestore(&data->lock, flags);
> + spin_unlock_irqrestore(&data->lock, flags);
>
> return ret;
> }
> @@ -528,7 +528,7 @@ static void sysmmu_tlb_invalidate_entry(struct device *dev, unsigned long iova)
> unsigned long flags;
> struct sysmmu_drvdata *data = dev_get_drvdata(dev->archdata.iommu);
>
> - read_lock_irqsave(&data->lock, flags);
> + spin_lock_irqsave(&data->lock, flags);
>
> if (is_sysmmu_active(data)) {
> int i;
> @@ -545,7 +545,7 @@ static void sysmmu_tlb_invalidate_entry(struct device *dev, unsigned long iova)
> data->dbgname);
> }
>
> - read_unlock_irqrestore(&data->lock, flags);
> + spin_unlock_irqrestore(&data->lock, flags);
> }
>
> void exynos_sysmmu_tlb_invalidate(struct device *dev)
> @@ -553,7 +553,7 @@ void exynos_sysmmu_tlb_invalidate(struct device *dev)
> unsigned long flags;
> struct sysmmu_drvdata *data = dev_get_drvdata(dev->archdata.iommu);
>
> - read_lock_irqsave(&data->lock, flags);
> + spin_lock_irqsave(&data->lock, flags);
>
> if (is_sysmmu_active(data)) {
> int i;
> @@ -569,7 +569,7 @@ void exynos_sysmmu_tlb_invalidate(struct device *dev)
> data->dbgname);
> }
>
> - read_unlock_irqrestore(&data->lock, flags);
> + spin_unlock_irqrestore(&data->lock, flags);
> }
>
> static int exynos_sysmmu_probe(struct platform_device *pdev)
> @@ -666,7 +666,7 @@ static int exynos_sysmmu_probe(struct platform_device *pdev)
> }
>
> data->sysmmu = dev;
> - rwlock_init(&data->lock);
> + spin_lock_init(&data->lock);
> INIT_LIST_HEAD(&data->node);
>
> __set_fault_handler(data, &default_fault_handler);
--
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