[PATCH v9 04/16] iommu/exynos: allocate lv2 page table from own slab

[PATCH v9 04/16] iommu/exynos: allocate lv2 page table from own slab

[Cho KyongHo]

Since kmalloc() does not guarantee that the allignment of 1KiB when it
allocates 1KiB, it is required to allocate lv2 page table from own
slab that guarantees alignment of 1KiB

Signed-off-by: Cho KyongHo <pullip.cho@samsung.com>
---
 drivers/iommu/exynos-iommu.c |   24 ++++++++++++++++++++----
 1 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
index d90e6fa..a318049 100644
--- a/drivers/iommu/exynos-iommu.c
+++ b/drivers/iommu/exynos-iommu.c
@@ -100,6 +100,8 @@
 #define REG_PB1_SADDR		0x054
 #define REG_PB1_EADDR		0x058
 
+static struct kmem_cache *lv2table_kmem_cache;
+
 static unsigned long *section_entry(unsigned long *pgtable, unsigned long iova)
 {
 	return pgtable + lv1ent_offset(iova);
@@ -765,7 +767,8 @@ static void exynos_iommu_domain_destroy(struct iommu_domain *domain)
 
 	for (i = 0; i < NUM_LV1ENTRIES; i++)
 		if (lv1ent_page(priv->pgtable + i))
-			kfree(__va(lv2table_base(priv->pgtable + i)));
+			kmem_cache_free(lv2table_kmem_cache,
+					__va(lv2table_base(priv->pgtable + i)));
 
 	free_pages((unsigned long)priv->pgtable, 2);
 	free_pages((unsigned long)priv->lv2entcnt, 1);
@@ -861,7 +864,7 @@ static unsigned long *alloc_lv2entry(unsigned long *sent, unsigned long iova,
 	if (lv1ent_fault(sent)) {
 		unsigned long *pent;
 
-		pent = kzalloc(LV2TABLE_SIZE, GFP_ATOMIC);
+		pent = kmem_cache_zalloc(lv2table_kmem_cache, GFP_ATOMIC);
 		BUG_ON((unsigned long)pent & (LV2TABLE_SIZE - 1));
 		if (!pent)
 			return ERR_PTR(-ENOMEM);
@@ -881,7 +884,7 @@ static int lv1set_section(unsigned long *sent, phys_addr_t paddr, short *pgcnt)
 
 	if (lv1ent_page(sent)) {
 		BUG_ON(*pgcnt != NUM_LV2ENTRIES);
-		kfree(page_entry(sent, 0));
+		kmem_cache_free(lv2table_kmem_cache, page_entry(sent, 0));
 		*pgcnt = 0;
 	}
 
@@ -1082,10 +1085,23 @@ static int __init exynos_iommu_init(void)
 {
 	int ret;
 
+	lv2table_kmem_cache = kmem_cache_create("exynos-iommu-lv2table",
+				LV2TABLE_SIZE, LV2TABLE_SIZE, 0, NULL);
+	if (!lv2table_kmem_cache) {
+		pr_err("%s: Failed to create kmem cache\n", __func__);
+		return -ENOMEM;
+	}
+
 	ret = platform_driver_register(&exynos_sysmmu_driver);
 
 	if (ret == 0)
-		bus_set_iommu(&platform_bus_type, &exynos_iommu_ops);
+		ret = bus_set_iommu(&platform_bus_type, &exynos_iommu_ops);
+
+	if (ret) {
+		pr_err("%s: Failed to register exynos-iommu driver.\n",
+								__func__);
+		kmem_cache_destroy(lv2table_kmem_cache);
+	}
 
 	return ret;
 }
-- 
1.7.2.5

Re: [PATCH v9 04/16] iommu/exynos: allocate lv2 page table from own slab

[Tomasz Figa]

On Thursday 08 of August 2013 18:38:04 Cho KyongHo wrote:
> Since kmalloc() does not guarantee that the allignment of 1KiB when it
> allocates 1KiB, it is required to allocate lv2 page table from own
> slab that guarantees alignment of 1KiB
> 
> Signed-off-by: Cho KyongHo <pullip.cho@samsung.com>
> ---
>  drivers/iommu/exynos-iommu.c |   24 ++++++++++++++++++++----
>  1 files changed, 20 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
> index d90e6fa..a318049 100644
> --- a/drivers/iommu/exynos-iommu.c
> +++ b/drivers/iommu/exynos-iommu.c
> @@ -100,6 +100,8 @@
>  #define REG_PB1_SADDR		0x054
>  #define REG_PB1_EADDR		0x058
> 
> +static struct kmem_cache *lv2table_kmem_cache;
> +
>  static unsigned long *section_entry(unsigned long *pgtable, unsigned
> long iova) {
>  	return pgtable + lv1ent_offset(iova);
> @@ -765,7 +767,8 @@ static void exynos_iommu_domain_destroy(struct
> iommu_domain *domain)
> 
>  	for (i = 0; i < NUM_LV1ENTRIES; i++)
>  		if (lv1ent_page(priv->pgtable + i))
> -			kfree(__va(lv2table_base(priv->pgtable + i)));
> +			kmem_cache_free(lv2table_kmem_cache,
> +					__va(lv2table_base(priv->pgtable + i)));
> 
>  	free_pages((unsigned long)priv->pgtable, 2);
>  	free_pages((unsigned long)priv->lv2entcnt, 1);
> @@ -861,7 +864,7 @@ static unsigned long *alloc_lv2entry(unsigned long
> *sent, unsigned long iova, if (lv1ent_fault(sent)) {
>  		unsigned long *pent;
> 
> -		pent = kzalloc(LV2TABLE_SIZE, GFP_ATOMIC);
> +		pent = kmem_cache_zalloc(lv2table_kmem_cache, GFP_ATOMIC);
>  		BUG_ON((unsigned long)pent & (LV2TABLE_SIZE - 1));
>  		if (!pent)
>  			return ERR_PTR(-ENOMEM);
> @@ -881,7 +884,7 @@ static int lv1set_section(unsigned long *sent,
> phys_addr_t paddr, short *pgcnt)
> 
>  	if (lv1ent_page(sent)) {
>  		BUG_ON(*pgcnt != NUM_LV2ENTRIES);
> -		kfree(page_entry(sent, 0));
> +		kmem_cache_free(lv2table_kmem_cache, page_entry(sent, 0));
>  		*pgcnt = 0;
>  	}
> 
> @@ -1082,10 +1085,23 @@ static int __init exynos_iommu_init(void)
>  {
>  	int ret;
> 
> +	lv2table_kmem_cache = kmem_cache_create("exynos-iommu-lv2table",
> +				LV2TABLE_SIZE, LV2TABLE_SIZE, 0, NULL);
> +	if (!lv2table_kmem_cache) {
> +		pr_err("%s: Failed to create kmem cache\n", __func__);
> +		return -ENOMEM;
> +	}
> +
>  	ret = platform_driver_register(&exynos_sysmmu_driver);
> 
>  	if (ret == 0)
> -		bus_set_iommu(&platform_bus_type, &exynos_iommu_ops);
> +		ret = bus_set_iommu(&platform_bus_type, &exynos_iommu_ops);
> +
> +	if (ret) {
> +		pr_err("%s: Failed to register exynos-iommu driver.\n",
> +								__func__);
> +		kmem_cache_destroy(lv2table_kmem_cache);
> +	}

What about making the return value handling here cleaner? For example:

	lv2table_kmem_cache = kmem_cache_create("exynos-iommu-lv2table",
				LV2TABLE_SIZE, LV2TABLE_SIZE, 0, NULL);
	if (!lv2table_kmem_cache) {
		...
		return -ENOMEM;
	}

	ret = platform_driver_register(&exynos_sysmmu_driver);
	if (ret) {
		...
		goto err_destroy_kmem_cache;
	}

	ret = bus_set_iommu(&platform_bus_type, &exynos_iommu_ops);
	if (ret) {
		...
		goto err_platform_unregister;
	}

	return 0;

err_platform_unregister:
	...
err_destroy_kmem_cache:
	...
	return ret;
}

Best regards,
Tomasz

Re: [PATCH v9 04/16] iommu/exynos: allocate lv2 page table from own slab

[Cho KyongHo]

On Thu, 08 Aug 2013 16:00:18 +0200, Tomasz Figa wrote:
> On Thursday 08 of August 2013 18:38:04 Cho KyongHo wrote:
> > Since kmalloc() does not guarantee that the allignment of 1KiB when it
> > allocates 1KiB, it is required to allocate lv2 page table from own
> > slab that guarantees alignment of 1KiB
> > 
> > Signed-off-by: Cho KyongHo <pullip.cho@samsung.com>
> > ---
> >  drivers/iommu/exynos-iommu.c |   24 ++++++++++++++++++++----
> >  1 files changed, 20 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
> > index d90e6fa..a318049 100644
> > --- a/drivers/iommu/exynos-iommu.c
> > +++ b/drivers/iommu/exynos-iommu.c
> > @@ -100,6 +100,8 @@
> >  #define REG_PB1_SADDR		0x054
> >  #define REG_PB1_EADDR		0x058
> > 
> > +static struct kmem_cache *lv2table_kmem_cache;
> > +
> >  static unsigned long *section_entry(unsigned long *pgtable, unsigned
> > long iova) {
> >  	return pgtable + lv1ent_offset(iova);
> > @@ -765,7 +767,8 @@ static void exynos_iommu_domain_destroy(struct
> > iommu_domain *domain)
> > 
> >  	for (i = 0; i < NUM_LV1ENTRIES; i++)
> >  		if (lv1ent_page(priv->pgtable + i))
> > -			kfree(__va(lv2table_base(priv->pgtable + i)));
> > +			kmem_cache_free(lv2table_kmem_cache,
> > +					__va(lv2table_base(priv->pgtable + i)));
> > 
> >  	free_pages((unsigned long)priv->pgtable, 2);
> >  	free_pages((unsigned long)priv->lv2entcnt, 1);
> > @@ -861,7 +864,7 @@ static unsigned long *alloc_lv2entry(unsigned long
> > *sent, unsigned long iova, if (lv1ent_fault(sent)) {
> >  		unsigned long *pent;
> > 
> > -		pent = kzalloc(LV2TABLE_SIZE, GFP_ATOMIC);
> > +		pent = kmem_cache_zalloc(lv2table_kmem_cache, GFP_ATOMIC);
> >  		BUG_ON((unsigned long)pent & (LV2TABLE_SIZE - 1));
> >  		if (!pent)
> >  			return ERR_PTR(-ENOMEM);
> > @@ -881,7 +884,7 @@ static int lv1set_section(unsigned long *sent,
> > phys_addr_t paddr, short *pgcnt)
> > 
> >  	if (lv1ent_page(sent)) {
> >  		BUG_ON(*pgcnt != NUM_LV2ENTRIES);
> > -		kfree(page_entry(sent, 0));
> > +		kmem_cache_free(lv2table_kmem_cache, page_entry(sent, 0));
> >  		*pgcnt = 0;
> >  	}
> > 
> > @@ -1082,10 +1085,23 @@ static int __init exynos_iommu_init(void)
> >  {
> >  	int ret;
> > 
> > +	lv2table_kmem_cache = kmem_cache_create("exynos-iommu-lv2table",
> > +				LV2TABLE_SIZE, LV2TABLE_SIZE, 0, NULL);
> > +	if (!lv2table_kmem_cache) {
> > +		pr_err("%s: Failed to create kmem cache\n", __func__);
> > +		return -ENOMEM;
> > +	}
> > +
> >  	ret = platform_driver_register(&exynos_sysmmu_driver);
> > 
> >  	if (ret == 0)
> > -		bus_set_iommu(&platform_bus_type, &exynos_iommu_ops);
> > +		ret = bus_set_iommu(&platform_bus_type, &exynos_iommu_ops);
> > +
> > +	if (ret) {
> > +		pr_err("%s: Failed to register exynos-iommu driver.\n",
> > +								__func__);
> > +		kmem_cache_destroy(lv2table_kmem_cache);
> > +	}
> 
> What about making the return value handling here cleaner? For example:
> 
> 	lv2table_kmem_cache = kmem_cache_create("exynos-iommu-lv2table",
> 				LV2TABLE_SIZE, LV2TABLE_SIZE, 0, NULL);
> 	if (!lv2table_kmem_cache) {
> 		...
> 		return -ENOMEM;
> 	}
> 
> 	ret = platform_driver_register(&exynos_sysmmu_driver);
> 	if (ret) {
> 		...
> 		goto err_destroy_kmem_cache;
> 	}
> 
> 	ret = bus_set_iommu(&platform_bus_type, &exynos_iommu_ops);
> 	if (ret) {
> 		...
> 		goto err_platform_unregister;
> 	}
> 
> 	return 0;
> 
> err_platform_unregister:
> 	...
> err_destroy_kmem_cache:
> 	...
> 	return ret;
> }
> 

Thank you for suggestion.
I think you are worrying about missing the information who makes 'ret' non-zero.
Ok. I will process it separately.

thanks

KyongHo.
> Best regards,
> Tomasz
> 

Re: [PATCH v9 04/16] iommu/exynos: allocate lv2 page table from own slab

[Tomasz Figa]

Hi KyongHo,

On Friday 09 of August 2013 14:58:49 Cho KyongHo wrote:
> On Thu, 08 Aug 2013 16:00:18 +0200, Tomasz Figa wrote:
> > On Thursday 08 of August 2013 18:38:04 Cho KyongHo wrote:
> > > Since kmalloc() does not guarantee that the allignment of 1KiB when
> > > it
> > > allocates 1KiB, it is required to allocate lv2 page table from own
> > > slab that guarantees alignment of 1KiB
> > > 
> > > Signed-off-by: Cho KyongHo <pullip.cho@samsung.com>
> > > ---
> > > 
> > >  drivers/iommu/exynos-iommu.c |   24 ++++++++++++++++++++----
> > >  1 files changed, 20 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/drivers/iommu/exynos-iommu.c
> > > b/drivers/iommu/exynos-iommu.c index d90e6fa..a318049 100644
> > > --- a/drivers/iommu/exynos-iommu.c
> > > +++ b/drivers/iommu/exynos-iommu.c
> > > @@ -100,6 +100,8 @@
> > > 
> > >  #define REG_PB1_SADDR		0x054
> > >  #define REG_PB1_EADDR		0x058
> > > 
> > > +static struct kmem_cache *lv2table_kmem_cache;
> > > +
> > > 
> > >  static unsigned long *section_entry(unsigned long *pgtable,
> > >  unsigned
> > > 
> > > long iova) {
> > > 
> > >  	return pgtable + lv1ent_offset(iova);
> > > 
> > > @@ -765,7 +767,8 @@ static void exynos_iommu_domain_destroy(struct
> > > iommu_domain *domain)
> > > 
> > >  	for (i = 0; i < NUM_LV1ENTRIES; i++)
> > >  	
> > >  		if (lv1ent_page(priv->pgtable + i))
> > > 
> > > -			kfree(__va(lv2table_base(priv->pgtable + i)));
> > > +			kmem_cache_free(lv2table_kmem_cache,
> > > +					__va(lv2table_base(priv->pgtable + 
i)));
> > > 
> > >  	free_pages((unsigned long)priv->pgtable, 2);
> > >  	free_pages((unsigned long)priv->lv2entcnt, 1);
> > > 
> > > @@ -861,7 +864,7 @@ static unsigned long *alloc_lv2entry(unsigned
> > > long
> > > *sent, unsigned long iova, if (lv1ent_fault(sent)) {
> > > 
> > >  		unsigned long *pent;
> > > 
> > > -		pent = kzalloc(LV2TABLE_SIZE, GFP_ATOMIC);
> > > +		pent = kmem_cache_zalloc(lv2table_kmem_cache, GFP_ATOMIC);
> > > 
> > >  		BUG_ON((unsigned long)pent & (LV2TABLE_SIZE - 1));
> > >  		if (!pent)
> > >  		
> > >  			return ERR_PTR(-ENOMEM);
> > > 
> > > @@ -881,7 +884,7 @@ static int lv1set_section(unsigned long *sent,
> > > phys_addr_t paddr, short *pgcnt)
> > > 
> > >  	if (lv1ent_page(sent)) {
> > >  	
> > >  		BUG_ON(*pgcnt != NUM_LV2ENTRIES);
> > > 
> > > -		kfree(page_entry(sent, 0));
> > > +		kmem_cache_free(lv2table_kmem_cache, page_entry(sent, 0));
> > > 
> > >  		*pgcnt = 0;
> > >  	
> > >  	}
> > > 
> > > @@ -1082,10 +1085,23 @@ static int __init exynos_iommu_init(void)
> > > 
> > >  {
> > >  
> > >  	int ret;
> > > 
> > > +	lv2table_kmem_cache = kmem_cache_create("exynos-iommu-lv2table",
> > > +				LV2TABLE_SIZE, LV2TABLE_SIZE, 0, NULL);
> > > +	if (!lv2table_kmem_cache) {
> > > +		pr_err("%s: Failed to create kmem cache\n", __func__);
> > > +		return -ENOMEM;
> > > +	}
> > > +
> > > 
> > >  	ret = platform_driver_register(&exynos_sysmmu_driver);
> > >  	
> > >  	if (ret == 0)
> > > 
> > > -		bus_set_iommu(&platform_bus_type, &exynos_iommu_ops);
> > > +		ret = bus_set_iommu(&platform_bus_type, 
&exynos_iommu_ops);
> > > +
> > > +	if (ret) {
> > > +		pr_err("%s: Failed to register exynos-iommu driver.\n",
> > > +								__func__);
> > > +		kmem_cache_destroy(lv2table_kmem_cache);
> > > +	}
> > 
> > What about making the return value handling here cleaner? For example:
> > 	lv2table_kmem_cache = kmem_cache_create("exynos-iommu-lv2table",
> > 	
> > 				LV2TABLE_SIZE, LV2TABLE_SIZE, 0, NULL);
> > 	
> > 	if (!lv2table_kmem_cache) {
> > 	
> > 		...
> > 		return -ENOMEM;
> > 	
> > 	}
> > 	
> > 	ret = platform_driver_register(&exynos_sysmmu_driver);
> > 	if (ret) {
> > 	
> > 		...
> > 		goto err_destroy_kmem_cache;
> > 	
> > 	}
> > 	
> > 	ret = bus_set_iommu(&platform_bus_type, &exynos_iommu_ops);
> > 	if (ret) {
> > 	
> > 		...
> > 		goto err_platform_unregister;
> > 	
> > 	}
> > 	
> > 	return 0;
> > 
> > err_platform_unregister:
> > 	...
> > 
> > err_destroy_kmem_cache:
> > 	...
> > 	return ret;
> > 
> > }
> 
> Thank you for suggestion.
> I think you are worrying about missing the information who makes 'ret'
> non-zero.

Oh, this is a valid point, but it was more a nitpick about the coding 
style. Single path error handling (with goto) is widely used in the kernel 
in cases when more than one thing has to be undone and so I suggested this 
method of error handling here as well.

> Ok. I will process it separately.

Since this patch adds most of the error handling to this function, I think 
it should be fine to do it as a part of this patch.

Best regards,
Tomasz

Re: [PATCH v9 04/16] iommu/exynos: allocate lv2 page table from own slab

[Cho KyongHo]

On Fri, 09 Aug 2013 09:55:30 +0200, Tomasz Figa wrote:
> Hi KyongHo,
> 
> On Friday 09 of August 2013 14:58:49 Cho KyongHo wrote:
> > On Thu, 08 Aug 2013 16:00:18 +0200, Tomasz Figa wrote:
> > > On Thursday 08 of August 2013 18:38:04 Cho KyongHo wrote:
> > > > Since kmalloc() does not guarantee that the allignment of 1KiB when
> > > > it
> > > > allocates 1KiB, it is required to allocate lv2 page table from own
> > > > slab that guarantees alignment of 1KiB
> > > > 
> > > > Signed-off-by: Cho KyongHo <pullip.cho@samsung.com>
> > > > ---
> > > > 
> > > >  drivers/iommu/exynos-iommu.c |   24 ++++++++++++++++++++----
> > > >  1 files changed, 20 insertions(+), 4 deletions(-)
> > > > 
> > > > diff --git a/drivers/iommu/exynos-iommu.c
> > > > b/drivers/iommu/exynos-iommu.c index d90e6fa..a318049 100644
> > > > --- a/drivers/iommu/exynos-iommu.c
> > > > +++ b/drivers/iommu/exynos-iommu.c
> > > > @@ -100,6 +100,8 @@
> > > > 
> > > >  #define REG_PB1_SADDR		0x054
> > > >  #define REG_PB1_EADDR		0x058
> > > > 
> > > > +static struct kmem_cache *lv2table_kmem_cache;
> > > > +
> > > > 
> > > >  static unsigned long *section_entry(unsigned long *pgtable,
> > > >  unsigned
> > > > 
> > > > long iova) {
> > > > 
> > > >  	return pgtable + lv1ent_offset(iova);
> > > > 
> > > > @@ -765,7 +767,8 @@ static void exynos_iommu_domain_destroy(struct
> > > > iommu_domain *domain)
> > > > 
> > > >  	for (i = 0; i < NUM_LV1ENTRIES; i++)
> > > >  	
> > > >  		if (lv1ent_page(priv->pgtable + i))
> > > > 
> > > > -			kfree(__va(lv2table_base(priv->pgtable + i)));
> > > > +			kmem_cache_free(lv2table_kmem_cache,
> > > > +					__va(lv2table_base(priv->pgtable + 
> i)));
> > > > 
> > > >  	free_pages((unsigned long)priv->pgtable, 2);
> > > >  	free_pages((unsigned long)priv->lv2entcnt, 1);
> > > > 
> > > > @@ -861,7 +864,7 @@ static unsigned long *alloc_lv2entry(unsigned
> > > > long
> > > > *sent, unsigned long iova, if (lv1ent_fault(sent)) {
> > > > 
> > > >  		unsigned long *pent;
> > > > 
> > > > -		pent = kzalloc(LV2TABLE_SIZE, GFP_ATOMIC);
> > > > +		pent = kmem_cache_zalloc(lv2table_kmem_cache, GFP_ATOMIC);
> > > > 
> > > >  		BUG_ON((unsigned long)pent & (LV2TABLE_SIZE - 1));
> > > >  		if (!pent)
> > > >  		
> > > >  			return ERR_PTR(-ENOMEM);
> > > > 
> > > > @@ -881,7 +884,7 @@ static int lv1set_section(unsigned long *sent,
> > > > phys_addr_t paddr, short *pgcnt)
> > > > 
> > > >  	if (lv1ent_page(sent)) {
> > > >  	
> > > >  		BUG_ON(*pgcnt != NUM_LV2ENTRIES);
> > > > 
> > > > -		kfree(page_entry(sent, 0));
> > > > +		kmem_cache_free(lv2table_kmem_cache, page_entry(sent, 0));
> > > > 
> > > >  		*pgcnt = 0;
> > > >  	
> > > >  	}
> > > > 
> > > > @@ -1082,10 +1085,23 @@ static int __init exynos_iommu_init(void)
> > > > 
> > > >  {
> > > >  
> > > >  	int ret;
> > > > 
> > > > +	lv2table_kmem_cache = kmem_cache_create("exynos-iommu-lv2table",
> > > > +				LV2TABLE_SIZE, LV2TABLE_SIZE, 0, NULL);
> > > > +	if (!lv2table_kmem_cache) {
> > > > +		pr_err("%s: Failed to create kmem cache\n", __func__);
> > > > +		return -ENOMEM;
> > > > +	}
> > > > +
> > > > 
> > > >  	ret = platform_driver_register(&exynos_sysmmu_driver);
> > > >  	
> > > >  	if (ret == 0)
> > > > 
> > > > -		bus_set_iommu(&platform_bus_type, &exynos_iommu_ops);
> > > > +		ret = bus_set_iommu(&platform_bus_type, 
> &exynos_iommu_ops);
> > > > +
> > > > +	if (ret) {
> > > > +		pr_err("%s: Failed to register exynos-iommu driver.\n",
> > > > +								__func__);
> > > > +		kmem_cache_destroy(lv2table_kmem_cache);
> > > > +	}
> > > 
> > > What about making the return value handling here cleaner? For example:
> > > 	lv2table_kmem_cache = kmem_cache_create("exynos-iommu-lv2table",
> > > 	
> > > 				LV2TABLE_SIZE, LV2TABLE_SIZE, 0, NULL);
> > > 	
> > > 	if (!lv2table_kmem_cache) {
> > > 	
> > > 		...
> > > 		return -ENOMEM;
> > > 	
> > > 	}
> > > 	
> > > 	ret = platform_driver_register(&exynos_sysmmu_driver);
> > > 	if (ret) {
> > > 	
> > > 		...
> > > 		goto err_destroy_kmem_cache;
> > > 	
> > > 	}
> > > 	
> > > 	ret = bus_set_iommu(&platform_bus_type, &exynos_iommu_ops);
> > > 	if (ret) {
> > > 	
> > > 		...
> > > 		goto err_platform_unregister;
> > > 	
> > > 	}
> > > 	
> > > 	return 0;
> > > 
> > > err_platform_unregister:
> > > 	...
> > > 
> > > err_destroy_kmem_cache:
> > > 	...
> > > 	return ret;
> > > 
> > > }
> > 
> > Thank you for suggestion.
> > I think you are worrying about missing the information who makes 'ret'
> > non-zero.
> 
> Oh, this is a valid point, but it was more a nitpick about the coding 
> style. Single path error handling (with goto) is widely used in the kernel 
> in cases when more than one thing has to be undone and so I suggested this 
> method of error handling here as well.
> 
> > Ok. I will process it separately.
> 
> Since this patch adds most of the error handling to this function, I think 
> it should be fine to do it as a part of this patch.
> 

I meant 'separately' that checking all return values each.
I think it can be simpler without goto.
There are just 2 cases to rollback previous changes in that function.

> Best regards,
> Tomasz
> 

Re: [PATCH v9 04/16] iommu/exynos: allocate lv2 page table from own slab

[Tomasz Figa]

On Friday 09 of August 2013 17:51:56 Cho KyongHo wrote:
> On Fri, 09 Aug 2013 09:55:30 +0200, Tomasz Figa wrote:
> > Hi KyongHo,
> > 
> > On Friday 09 of August 2013 14:58:49 Cho KyongHo wrote:
> > > On Thu, 08 Aug 2013 16:00:18 +0200, Tomasz Figa wrote:
> > > > On Thursday 08 of August 2013 18:38:04 Cho KyongHo wrote:
> > > > > Since kmalloc() does not guarantee that the allignment of 1KiB
> > > > > when
> > > > > it
> > > > > allocates 1KiB, it is required to allocate lv2 page table from
> > > > > own
> > > > > slab that guarantees alignment of 1KiB
> > > > > 
> > > > > Signed-off-by: Cho KyongHo <pullip.cho@samsung.com>
> > > > > ---
> > > > > 
> > > > >  drivers/iommu/exynos-iommu.c |   24 ++++++++++++++++++++----
> > > > >  1 files changed, 20 insertions(+), 4 deletions(-)
> > > > > 
> > > > > diff --git a/drivers/iommu/exynos-iommu.c
> > > > > b/drivers/iommu/exynos-iommu.c index d90e6fa..a318049 100644
> > > > > --- a/drivers/iommu/exynos-iommu.c
> > > > > +++ b/drivers/iommu/exynos-iommu.c
> > > > > @@ -100,6 +100,8 @@
> > > > > 
> > > > >  #define REG_PB1_SADDR		0x054
> > > > >  #define REG_PB1_EADDR		0x058
> > > > > 
> > > > > +static struct kmem_cache *lv2table_kmem_cache;
> > > > > +
> > > > > 
> > > > >  static unsigned long *section_entry(unsigned long *pgtable,
> > > > >  unsigned
> > > > > 
> > > > > long iova) {
> > > > > 
> > > > >  	return pgtable + lv1ent_offset(iova);
> > > > > 
> > > > > @@ -765,7 +767,8 @@ static void
> > > > > exynos_iommu_domain_destroy(struct
> > > > > iommu_domain *domain)
> > > > > 
> > > > >  	for (i = 0; i < NUM_LV1ENTRIES; i++)
> > > > >  	
> > > > >  		if (lv1ent_page(priv->pgtable + i))
> > > > > 
> > > > > -			kfree(__va(lv2table_base(priv->pgtable + i)));
> > > > > +			kmem_cache_free(lv2table_kmem_cache,
> > > > > +					__va(lv2table_base(priv->pgtable +
> > 
> > i)));
> > 
> > > > >  	free_pages((unsigned long)priv->pgtable, 2);
> > > > >  	free_pages((unsigned long)priv->lv2entcnt, 1);
> > > > > 
> > > > > @@ -861,7 +864,7 @@ static unsigned long *alloc_lv2entry(unsigned
> > > > > long
> > > > > *sent, unsigned long iova, if (lv1ent_fault(sent)) {
> > > > > 
> > > > >  		unsigned long *pent;
> > > > > 
> > > > > -		pent = kzalloc(LV2TABLE_SIZE, GFP_ATOMIC);
> > > > > +		pent = kmem_cache_zalloc(lv2table_kmem_cache, GFP_ATOMIC);
> > > > > 
> > > > >  		BUG_ON((unsigned long)pent & (LV2TABLE_SIZE - 1));
> > > > >  		if (!pent)
> > > > >  		
> > > > >  			return ERR_PTR(-ENOMEM);
> > > > > 
> > > > > @@ -881,7 +884,7 @@ static int lv1set_section(unsigned long
> > > > > *sent,
> > > > > phys_addr_t paddr, short *pgcnt)
> > > > > 
> > > > >  	if (lv1ent_page(sent)) {
> > > > >  	
> > > > >  		BUG_ON(*pgcnt != NUM_LV2ENTRIES);
> > > > > 
> > > > > -		kfree(page_entry(sent, 0));
> > > > > +		kmem_cache_free(lv2table_kmem_cache, page_entry(sent, 0));
> > > > > 
> > > > >  		*pgcnt = 0;
> > > > >  	
> > > > >  	}
> > > > > 
> > > > > @@ -1082,10 +1085,23 @@ static int __init exynos_iommu_init(void)
> > > > > 
> > > > >  {
> > > > >  
> > > > >  	int ret;
> > > > > 
> > > > > +	lv2table_kmem_cache =
> > > > > kmem_cache_create("exynos-iommu-lv2table",
> > > > > +				LV2TABLE_SIZE, LV2TABLE_SIZE, 0, NULL);
> > > > > +	if (!lv2table_kmem_cache) {
> > > > > +		pr_err("%s: Failed to create kmem cache\n", __func__);
> > > > > +		return -ENOMEM;
> > > > > +	}
> > > > > +
> > > > > 
> > > > >  	ret = platform_driver_register(&exynos_sysmmu_driver);
> > > > >  	
> > > > >  	if (ret == 0)
> > > > > 
> > > > > -		bus_set_iommu(&platform_bus_type, &exynos_iommu_ops);
> > > > > +		ret = bus_set_iommu(&platform_bus_type,
> > 
> > &exynos_iommu_ops);
> > 
> > > > > +
> > > > > +	if (ret) {
> > > > > +		pr_err("%s: Failed to register exynos-iommu driver.\n",
> > > > > +								__func__);
> > > > > +		kmem_cache_destroy(lv2table_kmem_cache);
> > > > > +	}
> > > > 
> > > > What about making the return value handling here cleaner? For 
example:
> > > > 	lv2table_kmem_cache = kmem_cache_create("exynos-iommu-lv2table",
> > > > 	
> > > > 				LV2TABLE_SIZE, LV2TABLE_SIZE, 0, NULL);
> > > > 	
> > > > 	if (!lv2table_kmem_cache) {
> > > > 	
> > > > 		...
> > > > 		return -ENOMEM;
> > > > 	
> > > > 	}
> > > > 	
> > > > 	ret = platform_driver_register(&exynos_sysmmu_driver);
> > > > 	if (ret) {
> > > > 	
> > > > 		...
> > > > 		goto err_destroy_kmem_cache;
> > > > 	
> > > > 	}
> > > > 	
> > > > 	ret = bus_set_iommu(&platform_bus_type, &exynos_iommu_ops);
> > > > 	if (ret) {
> > > > 	
> > > > 		...
> > > > 		goto err_platform_unregister;
> > > > 	
> > > > 	}
> > > > 	
> > > > 	return 0;
> > > > 
> > > > err_platform_unregister:
> > > > 	...
> > > > 
> > > > err_destroy_kmem_cache:
> > > > 	...
> > > > 	return ret;
> > > > 
> > > > }
> > > 
> > > Thank you for suggestion.
> > > I think you are worrying about missing the information who makes
> > > 'ret'
> > > non-zero.
> > 
> > Oh, this is a valid point, but it was more a nitpick about the coding
> > style. Single path error handling (with goto) is widely used in the
> > kernel in cases when more than one thing has to be undone and so I
> > suggested this method of error handling here as well.
> > 
> > > Ok. I will process it separately.
> > 
> > Since this patch adds most of the error handling to this function, I
> > think it should be fine to do it as a part of this patch.
> 
> I meant 'separately' that checking all return values each.
> I think it can be simpler without goto.
>
> There are just 2 cases to rollback previous changes in that function.

It might end up with less lines, but having roll back in single place is 
more readable. That's why it's the preferred error handling way in Linux 
kernel, if you have more than one action to undo on your error path.

Best regards,
Tomasz

Re: [PATCH v9 04/16] iommu/exynos: allocate lv2 page table from own slab

[Cho KyongHo]

On Fri, 09 Aug 2013 11:35:20 +0200, Tomasz Figa wrote:
> On Friday 09 of August 2013 17:51:56 Cho KyongHo wrote:
> > On Fri, 09 Aug 2013 09:55:30 +0200, Tomasz Figa wrote:
> > > Hi KyongHo,
> > > 
> > > On Friday 09 of August 2013 14:58:49 Cho KyongHo wrote:
> > > > On Thu, 08 Aug 2013 16:00:18 +0200, Tomasz Figa wrote:
> > > > > On Thursday 08 of August 2013 18:38:04 Cho KyongHo wrote:
> > > > > > Since kmalloc() does not guarantee that the allignment of 1KiB
> > > > > > when
> > > > > > it
> > > > > > allocates 1KiB, it is required to allocate lv2 page table from
> > > > > > own
> > > > > > slab that guarantees alignment of 1KiB
> > > > > > 
> > > > > > Signed-off-by: Cho KyongHo <pullip.cho@samsung.com>
> > > > > > ---
> > > > > > 
> > > > > >  drivers/iommu/exynos-iommu.c |   24 ++++++++++++++++++++----
> > > > > >  1 files changed, 20 insertions(+), 4 deletions(-)
> > > > > > 
> > > > > > diff --git a/drivers/iommu/exynos-iommu.c
> > > > > > b/drivers/iommu/exynos-iommu.c index d90e6fa..a318049 100644
> > > > > > --- a/drivers/iommu/exynos-iommu.c
> > > > > > +++ b/drivers/iommu/exynos-iommu.c
> > > > > > @@ -100,6 +100,8 @@
> > > > > > 
> > > > > >  #define REG_PB1_SADDR		0x054
> > > > > >  #define REG_PB1_EADDR		0x058
> > > > > > 
> > > > > > +static struct kmem_cache *lv2table_kmem_cache;
> > > > > > +
> > > > > > 
> > > > > >  static unsigned long *section_entry(unsigned long *pgtable,
> > > > > >  unsigned
> > > > > > 
> > > > > > long iova) {
> > > > > > 
> > > > > >  	return pgtable + lv1ent_offset(iova);
> > > > > > 
> > > > > > @@ -765,7 +767,8 @@ static void
> > > > > > exynos_iommu_domain_destroy(struct
> > > > > > iommu_domain *domain)
> > > > > > 
> > > > > >  	for (i = 0; i < NUM_LV1ENTRIES; i++)
> > > > > >  	
> > > > > >  		if (lv1ent_page(priv->pgtable + i))
> > > > > > 
> > > > > > -			kfree(__va(lv2table_base(priv->pgtable + i)));
> > > > > > +			kmem_cache_free(lv2table_kmem_cache,
> > > > > > +					__va(lv2table_base(priv->pgtable +
> > > 
> > > i)));
> > > 
> > > > > >  	free_pages((unsigned long)priv->pgtable, 2);
> > > > > >  	free_pages((unsigned long)priv->lv2entcnt, 1);
> > > > > > 
> > > > > > @@ -861,7 +864,7 @@ static unsigned long *alloc_lv2entry(unsigned
> > > > > > long
> > > > > > *sent, unsigned long iova, if (lv1ent_fault(sent)) {
> > > > > > 
> > > > > >  		unsigned long *pent;
> > > > > > 
> > > > > > -		pent = kzalloc(LV2TABLE_SIZE, GFP_ATOMIC);
> > > > > > +		pent = kmem_cache_zalloc(lv2table_kmem_cache, GFP_ATOMIC);
> > > > > > 
> > > > > >  		BUG_ON((unsigned long)pent & (LV2TABLE_SIZE - 1));
> > > > > >  		if (!pent)
> > > > > >  		
> > > > > >  			return ERR_PTR(-ENOMEM);
> > > > > > 
> > > > > > @@ -881,7 +884,7 @@ static int lv1set_section(unsigned long
> > > > > > *sent,
> > > > > > phys_addr_t paddr, short *pgcnt)
> > > > > > 
> > > > > >  	if (lv1ent_page(sent)) {
> > > > > >  	
> > > > > >  		BUG_ON(*pgcnt != NUM_LV2ENTRIES);
> > > > > > 
> > > > > > -		kfree(page_entry(sent, 0));
> > > > > > +		kmem_cache_free(lv2table_kmem_cache, page_entry(sent, 0));
> > > > > > 
> > > > > >  		*pgcnt = 0;
> > > > > >  	
> > > > > >  	}
> > > > > > 
> > > > > > @@ -1082,10 +1085,23 @@ static int __init exynos_iommu_init(void)
> > > > > > 
> > > > > >  {
> > > > > >  
> > > > > >  	int ret;
> > > > > > 
> > > > > > +	lv2table_kmem_cache =
> > > > > > kmem_cache_create("exynos-iommu-lv2table",
> > > > > > +				LV2TABLE_SIZE, LV2TABLE_SIZE, 0, NULL);
> > > > > > +	if (!lv2table_kmem_cache) {
> > > > > > +		pr_err("%s: Failed to create kmem cache\n", __func__);
> > > > > > +		return -ENOMEM;
> > > > > > +	}
> > > > > > +
> > > > > > 
> > > > > >  	ret = platform_driver_register(&exynos_sysmmu_driver);
> > > > > >  	
> > > > > >  	if (ret == 0)
> > > > > > 
> > > > > > -		bus_set_iommu(&platform_bus_type, &exynos_iommu_ops);
> > > > > > +		ret = bus_set_iommu(&platform_bus_type,
> > > 
> > > &exynos_iommu_ops);
> > > 
> > > > > > +
> > > > > > +	if (ret) {
> > > > > > +		pr_err("%s: Failed to register exynos-iommu driver.\n",
> > > > > > +								__func__);
> > > > > > +		kmem_cache_destroy(lv2table_kmem_cache);
> > > > > > +	}
> > > > > 
> > > > > What about making the return value handling here cleaner? For 
> example:
> > > > > 	lv2table_kmem_cache = kmem_cache_create("exynos-iommu-lv2table",
> > > > > 	
> > > > > 				LV2TABLE_SIZE, LV2TABLE_SIZE, 0, NULL);
> > > > > 	
> > > > > 	if (!lv2table_kmem_cache) {
> > > > > 	
> > > > > 		...
> > > > > 		return -ENOMEM;
> > > > > 	
> > > > > 	}
> > > > > 	
> > > > > 	ret = platform_driver_register(&exynos_sysmmu_driver);
> > > > > 	if (ret) {
> > > > > 	
> > > > > 		...
> > > > > 		goto err_destroy_kmem_cache;
> > > > > 	
> > > > > 	}
> > > > > 	
> > > > > 	ret = bus_set_iommu(&platform_bus_type, &exynos_iommu_ops);
> > > > > 	if (ret) {
> > > > > 	
> > > > > 		...
> > > > > 		goto err_platform_unregister;
> > > > > 	
> > > > > 	}
> > > > > 	
> > > > > 	return 0;
> > > > > 
> > > > > err_platform_unregister:
> > > > > 	...
> > > > > 
> > > > > err_destroy_kmem_cache:
> > > > > 	...
> > > > > 	return ret;
> > > > > 
> > > > > }
> > > > 
> > > > Thank you for suggestion.
> > > > I think you are worrying about missing the information who makes
> > > > 'ret'
> > > > non-zero.
> > > 
> > > Oh, this is a valid point, but it was more a nitpick about the coding
> > > style. Single path error handling (with goto) is widely used in the
> > > kernel in cases when more than one thing has to be undone and so I
> > > suggested this method of error handling here as well.
> > > 
> > > > Ok. I will process it separately.
> > > 
> > > Since this patch adds most of the error handling to this function, I
> > > think it should be fine to do it as a part of this patch.
> > 
> > I meant 'separately' that checking all return values each.
> > I think it can be simpler without goto.
> >
> > There are just 2 cases to rollback previous changes in that function.
> 
> It might end up with less lines, but having roll back in single place is 
> more readable. That's why it's the preferred error handling way in Linux 
> kernel, if you have more than one action to undo on your error path.
> 

I fully understand what you are concerning about and I also agree.
Actually it is simple choice without any side effect.
It is just a preference.
I will change it into 'goto'.
Then we can determine what looks better :) 

Thank you.

KyongHo.

> Best regards,
> Tomasz
> 

Re: [PATCH v9 04/16] iommu/exynos: allocate lv2 page table from own slab

['Joerg Roedel']

On Fri, Aug 09, 2013 at 09:55:30AM +0200, Tomasz Figa wrote:
> Oh, this is a valid point, but it was more a nitpick about the coding 
> style. Single path error handling (with goto) is widely used in the kernel 
> in cases when more than one thing has to be undone and so I suggested this 
> method of error handling here as well.

I agree with that review from Tomasz, the error-handling should look
similar to all the other places in the kernel and use goto.


	Joerg

Re: [PATCH v9 04/16] iommu/exynos: allocate lv2 page table from own slab

[Cho KyongHo]

On Wed, 14 Aug 2013 12:56:16 +0200, 'Joerg Roedel' wrote:
> On Fri, Aug 09, 2013 at 09:55:30AM +0200, Tomasz Figa wrote:
> > Oh, this is a valid point, but it was more a nitpick about the coding 
> > style. Single path error handling (with goto) is widely used in the kernel 
> > in cases when more than one thing has to be undone and so I suggested this 
> > method of error handling here as well.
> 
> I agree with that review from Tomasz, the error-handling should look
> similar to all the other places in the kernel and use goto.
> 
Ok.

Thanks.

KyongHo.
> 
> 	Joerg
> 
>