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[PATCH v11 05/10] genirq/msi-doorbell: msi_doorbell_pages

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  [PATCH v11 05/10] genirq/msi-doorbell: msi_doorbell_pages Eric Auger <eric.auger@redhat.com> - 2016-07-19 15:10 +0200
    Re: [PATCH v11 05/10] genirq/msi-doorbell: msi_doorbell_pages Thomas Gleixner <tglx@linutronix.de> - 2016-07-19 16:50 +0200
      Re: [PATCH v11 05/10] genirq/msi-doorbell: msi_doorbell_pages Auger Eric <eric.auger@redhat.com> - 2016-07-20 10:00 +0200
      Re: [PATCH v11 05/10] genirq/msi-doorbell: msi_doorbell_pages Auger Eric <eric.auger@redhat.com> - 2016-07-21 15:40 +0200

#1446430 — [PATCH v11 05/10] genirq/msi-doorbell: msi_doorbell_pages

msi_doorbell_pages sum up the number of iommu pages of a given order
requested to map all the registered doorbells. This function will allow
to dimension the intermediate physical address (IPA) aperture requested
to map the MSI doorbells.

Signed-off-by: Eric Auger <eric.auger@redhat.com>

---

v10: creation
---
 include/linux/msi-doorbell.h | 14 ++++++++++++
 kernel/irq/msi-doorbell.c    | 52 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 66 insertions(+)

diff --git a/include/linux/msi-doorbell.h b/include/linux/msi-doorbell.h
index c455e33..146bfbc 100644
--- a/include/linux/msi-doorbell.h
+++ b/include/linux/msi-doorbell.h
@@ -35,6 +35,14 @@ msi_doorbell_register_global(phys_addr_t base, size_t size,
  */
 void msi_doorbell_unregister_global(struct irq_chip_msi_doorbell_info *db);
 
+/**
+ * msi_doorbell_pages: compute the number of iommu pages of size 1 << order
+ * requested to map all the registered doorbells
+ *
+ * @order: iommu page order
+ */
+int msi_doorbell_pages(unsigned int order);
+
 #else
 
 static inline struct irq_chip_msi_doorbell_info *
@@ -47,6 +55,12 @@ msi_doorbell_register_global(phys_addr_t base, size_t size,
 static inline void
 msi_doorbell_unregister_global(struct irq_chip_msi_doorbell_info *db) {}
 
+static inline int
+msi_doorbell_pages(unsigned int order)
+{
+	return 0;
+}
+
 #endif /* CONFIG_MSI_DOORBELL */
 
 #endif
diff --git a/kernel/irq/msi-doorbell.c b/kernel/irq/msi-doorbell.c
index 0ff541e..a5bde37 100644
--- a/kernel/irq/msi-doorbell.c
+++ b/kernel/irq/msi-doorbell.c
@@ -60,3 +60,55 @@ void msi_doorbell_unregister_global(struct irq_chip_msi_doorbell_info *dbinfo)
 	mutex_unlock(&irqchip_doorbell_mutex);
 }
 EXPORT_SYMBOL_GPL(msi_doorbell_unregister_global);
+
+static int compute_db_mapping_requirements(phys_addr_t addr, size_t size,
+					   unsigned int order)
+{
+	phys_addr_t offset, granule;
+	unsigned int nb_pages;
+
+	granule = (uint64_t)(1 << order);
+	offset = addr & (granule - 1);
+	size = ALIGN(size + offset, granule);
+	nb_pages = size >> order;
+
+	return nb_pages;
+}
+
+static int
+compute_dbinfo_mapping_requirements(struct irq_chip_msi_doorbell_info *dbinfo,
+				    unsigned int order)
+{
+	int ret = 0;
+
+	if (!dbinfo->doorbell_is_percpu) {
+		ret = compute_db_mapping_requirements(dbinfo->global_doorbell,
+						      dbinfo->size, order);
+	} else {
+		phys_addr_t __percpu *pbase;
+		int cpu;
+
+		for_each_possible_cpu(cpu) {
+			pbase = per_cpu_ptr(dbinfo->percpu_doorbells, cpu);
+			ret += compute_db_mapping_requirements(*pbase,
+							       dbinfo->size,
+							       order);
+		}
+	}
+	return ret;
+}
+
+int msi_doorbell_pages(unsigned int order)
+{
+	struct irqchip_doorbell *db;
+	int ret = 0;
+
+	mutex_lock(&irqchip_doorbell_mutex);
+	list_for_each_entry(db, &irqchip_doorbell_list, next) {
+		ret += compute_dbinfo_mapping_requirements(&db->info, order);
+	}
+	mutex_unlock(&irqchip_doorbell_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(msi_doorbell_pages);
-- 
1.9.1

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#1446530

On Tue, 19 Jul 2016, Eric Auger wrote:
> msi_doorbell_pages sum up the number of iommu pages of a given order

adding () to the function name would make it immediately clear that
msi_doorbell_pages is a function.

> +/**
> + * msi_doorbell_pages: compute the number of iommu pages of size 1 << order
> + * requested to map all the registered doorbells
> + *
> + * @order: iommu page order
> + */

Why are you adding the kernel doc to the header and not to the implementation?

> +int msi_doorbell_pages(unsigned int order);
> +
>  #else
>  
>  static inline struct irq_chip_msi_doorbell_info *
> @@ -47,6 +55,12 @@ msi_doorbell_register_global(phys_addr_t base, size_t size,
>  static inline void
>  msi_doorbell_unregister_global(struct irq_chip_msi_doorbell_info *db) {}
>  
> +static inline int
> +msi_doorbell_pages(unsigned int order)

What's the point of this line break? 

> +{
> +	return 0;
> +}
> +
>  #endif /* CONFIG_MSI_DOORBELL */
>  
>  #endif
> diff --git a/kernel/irq/msi-doorbell.c b/kernel/irq/msi-doorbell.c
> index 0ff541e..a5bde37 100644
> --- a/kernel/irq/msi-doorbell.c
> +++ b/kernel/irq/msi-doorbell.c
> @@ -60,3 +60,55 @@ void msi_doorbell_unregister_global(struct irq_chip_msi_doorbell_info *dbinfo)
>  	mutex_unlock(&irqchip_doorbell_mutex);
>  }
>  EXPORT_SYMBOL_GPL(msi_doorbell_unregister_global);
> +
> +static int compute_db_mapping_requirements(phys_addr_t addr, size_t size,
> +					   unsigned int order)
> +{
> +	phys_addr_t offset, granule;
> +	unsigned int nb_pages;
> +
> +	granule = (uint64_t)(1 << order);
> +	offset = addr & (granule - 1);
> +	size = ALIGN(size + offset, granule);
> +	nb_pages = size >> order;
> +
> +	return nb_pages;
> +}
> +
> +static int
> +compute_dbinfo_mapping_requirements(struct irq_chip_msi_doorbell_info *dbinfo,
> +				    unsigned int order)

I'm sure you can find even longer function names which require more line
breaks.

> +{
> +	int ret = 0;
> +
> +	if (!dbinfo->doorbell_is_percpu) {
> +		ret = compute_db_mapping_requirements(dbinfo->global_doorbell,
> +						      dbinfo->size, order);
> +	} else {
> +		phys_addr_t __percpu *pbase;
> +		int cpu;
> +
> +		for_each_possible_cpu(cpu) {
> +			pbase = per_cpu_ptr(dbinfo->percpu_doorbells, cpu);
> +			ret += compute_db_mapping_requirements(*pbase,
> +							       dbinfo->size,
> +							       order);
> +		}
> +	}
> +	return ret;
> +}
> +
> +int msi_doorbell_pages(unsigned int order)
> +{
> +	struct irqchip_doorbell *db;
> +	int ret = 0;
> +
> +	mutex_lock(&irqchip_doorbell_mutex);
> +	list_for_each_entry(db, &irqchip_doorbell_list, next) {

Pointless braces

> +		ret += compute_dbinfo_mapping_requirements(&db->info, order);
> +	}
> +	mutex_unlock(&irqchip_doorbell_mutex);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(msi_doorbell_pages);

So here is a general rant about your naming choices.

   struct irqchip_doorbell
   struct irq_chip_msi_doorbell_info

   struct irq_chip {
   	  ....	  *(*msi_doorbell_info);
   }

   irqchip_doorbell_mutex

   msi_doorbell_register_global
   msi_doorbell_unregister_global

   msi_doorbell_pages

This really sucks. Your public functions start sensibly with msi_doorbell.

Though what is the _global postfix for the register/unregister functions for?
Are there _private functions in the pipeline?

msi_doorbell_pages() is not telling me what it does. msi_calc_doorbell_pages()
would describe it right away.

You doorbell info structure can really do with:

    struct msi_doorbell_info;

And the wrapper struct around it is fine with:

    struct msi_doorbell;

Thanks,

	tglx

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#1447059

Hi Thomas,
On 19/07/2016 16:38, Thomas Gleixner wrote:
> On Tue, 19 Jul 2016, Eric Auger wrote:
>> msi_doorbell_pages sum up the number of iommu pages of a given order
> 
> adding () to the function name would make it immediately clear that
> msi_doorbell_pages is a function.
> 
>> +/**
>> + * msi_doorbell_pages: compute the number of iommu pages of size 1 << order
>> + * requested to map all the registered doorbells
>> + *
>> + * @order: iommu page order
>> + */
> 
> Why are you adding the kernel doc to the header and not to the implementation?
> 
>> +int msi_doorbell_pages(unsigned int order);
>> +
>>  #else
>>  
>>  static inline struct irq_chip_msi_doorbell_info *
>> @@ -47,6 +55,12 @@ msi_doorbell_register_global(phys_addr_t base, size_t size,
>>  static inline void
>>  msi_doorbell_unregister_global(struct irq_chip_msi_doorbell_info *db) {}
>>  
>> +static inline int
>> +msi_doorbell_pages(unsigned int order)
> 
> What's the point of this line break?

> 
>> +{
>> +	return 0;
>> +}
>> +
>>  #endif /* CONFIG_MSI_DOORBELL */
>>  
>>  #endif
>> diff --git a/kernel/irq/msi-doorbell.c b/kernel/irq/msi-doorbell.c
>> index 0ff541e..a5bde37 100644
>> --- a/kernel/irq/msi-doorbell.c
>> +++ b/kernel/irq/msi-doorbell.c
>> @@ -60,3 +60,55 @@ void msi_doorbell_unregister_global(struct irq_chip_msi_doorbell_info *dbinfo)
>>  	mutex_unlock(&irqchip_doorbell_mutex);
>>  }
>>  EXPORT_SYMBOL_GPL(msi_doorbell_unregister_global);
>> +
>> +static int compute_db_mapping_requirements(phys_addr_t addr, size_t size,
>> +					   unsigned int order)
>> +{
>> +	phys_addr_t offset, granule;
>> +	unsigned int nb_pages;
>> +
>> +	granule = (uint64_t)(1 << order);
>> +	offset = addr & (granule - 1);
>> +	size = ALIGN(size + offset, granule);
>> +	nb_pages = size >> order;
>> +
>> +	return nb_pages;
>> +}
>> +
>> +static int
>> +compute_dbinfo_mapping_requirements(struct irq_chip_msi_doorbell_info *dbinfo,
>> +				    unsigned int order)
> 
> I'm sure you can find even longer function names which require more line
> breaks.
> 
>> +{
>> +	int ret = 0;
>> +
>> +	if (!dbinfo->doorbell_is_percpu) {
>> +		ret = compute_db_mapping_requirements(dbinfo->global_doorbell,
>> +						      dbinfo->size, order);
>> +	} else {
>> +		phys_addr_t __percpu *pbase;
>> +		int cpu;
>> +
>> +		for_each_possible_cpu(cpu) {
>> +			pbase = per_cpu_ptr(dbinfo->percpu_doorbells, cpu);
>> +			ret += compute_db_mapping_requirements(*pbase,
>> +							       dbinfo->size,
>> +							       order);
>> +		}
>> +	}
>> +	return ret;
>> +}
>> +
>> +int msi_doorbell_pages(unsigned int order)
>> +{
>> +	struct irqchip_doorbell *db;
>> +	int ret = 0;
>> +
>> +	mutex_lock(&irqchip_doorbell_mutex);
>> +	list_for_each_entry(db, &irqchip_doorbell_list, next) {
> 
> Pointless braces
> 
>> +		ret += compute_dbinfo_mapping_requirements(&db->info, order);
>> +	}
>> +	mutex_unlock(&irqchip_doorbell_mutex);
>> +
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(msi_doorbell_pages);
> 
> So here is a general rant about your naming choices.
> 
>    struct irqchip_doorbell
>    struct irq_chip_msi_doorbell_info
> 
>    struct irq_chip {
>    	  ....	  *(*msi_doorbell_info);
>    }
> 
>    irqchip_doorbell_mutex
> 
>    msi_doorbell_register_global
>    msi_doorbell_unregister_global
> 
>    msi_doorbell_pages
> 
> This really sucks. Your public functions start sensibly with msi_doorbell.
> 
> Though what is the _global postfix for the register/unregister functions for?
> Are there _private functions in the pipeline?
global is to be opposed to per-cpu (doorbell). Currently gicv2m and
gicv3-its expose a single "global" doorbell and I have not yet coped
with irqchips exposing per-cpu doorbells.
> 
> msi_doorbell_pages() is not telling me what it does. msi_calc_doorbell_pages()
> would describe it right away.
> 
> You doorbell info structure can really do with:
> 
>     struct msi_doorbell_info;
> 
> And the wrapper struct around it is fine with:
> 
>     struct msi_doorbell;
Yes you're right I will revisit the names and fix all style issues you
reported.

Thank you for your time

Eric
> 
> Thanks,
> 
> 	tglx
> 

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#1447887

Hi Thomas,

On 19/07/2016 16:38, Thomas Gleixner wrote:
> On Tue, 19 Jul 2016, Eric Auger wrote:
>> msi_doorbell_pages sum up the number of iommu pages of a given order
> 
> adding () to the function name would make it immediately clear that
> msi_doorbell_pages is a function.
> 
>> +/**
>> + * msi_doorbell_pages: compute the number of iommu pages of size 1 << order
>> + * requested to map all the registered doorbells
>> + *
>> + * @order: iommu page order
>> + */
> 
> Why are you adding the kernel doc to the header and not to the implementation?

I am confused by this comment. I was told in the past that it was better
to put the comments in the API header. On your side do you want me to
move all function kernel-doc comments to the implementation.

Looking at kernel-doc-nano-HOWTO.txt, I was not able to find any
indication about the best choice.

I will now run the kernel-doc script to check the conformance of my
comments.

Thank you for your patience!

Best Regards

Eric
> 
>> +int msi_doorbell_pages(unsigned int order);
>> +
>>  #else
>>  
>>  static inline struct irq_chip_msi_doorbell_info *
>> @@ -47,6 +55,12 @@ msi_doorbell_register_global(phys_addr_t base, size_t size,
>>  static inline void
>>  msi_doorbell_unregister_global(struct irq_chip_msi_doorbell_info *db) {}
>>  
>> +static inline int
>> +msi_doorbell_pages(unsigned int order)
> 
> What's the point of this line break? 
> 
>> +{
>> +	return 0;
>> +}
>> +
>>  #endif /* CONFIG_MSI_DOORBELL */
>>  
>>  #endif
>> diff --git a/kernel/irq/msi-doorbell.c b/kernel/irq/msi-doorbell.c
>> index 0ff541e..a5bde37 100644
>> --- a/kernel/irq/msi-doorbell.c
>> +++ b/kernel/irq/msi-doorbell.c
>> @@ -60,3 +60,55 @@ void msi_doorbell_unregister_global(struct irq_chip_msi_doorbell_info *dbinfo)
>>  	mutex_unlock(&irqchip_doorbell_mutex);
>>  }
>>  EXPORT_SYMBOL_GPL(msi_doorbell_unregister_global);
>> +
>> +static int compute_db_mapping_requirements(phys_addr_t addr, size_t size,
>> +					   unsigned int order)
>> +{
>> +	phys_addr_t offset, granule;
>> +	unsigned int nb_pages;
>> +
>> +	granule = (uint64_t)(1 << order);
>> +	offset = addr & (granule - 1);
>> +	size = ALIGN(size + offset, granule);
>> +	nb_pages = size >> order;
>> +
>> +	return nb_pages;
>> +}
>> +
>> +static int
>> +compute_dbinfo_mapping_requirements(struct irq_chip_msi_doorbell_info *dbinfo,
>> +				    unsigned int order)
> 
> I'm sure you can find even longer function names which require more line
> breaks.
> 
>> +{
>> +	int ret = 0;
>> +
>> +	if (!dbinfo->doorbell_is_percpu) {
>> +		ret = compute_db_mapping_requirements(dbinfo->global_doorbell,
>> +						      dbinfo->size, order);
>> +	} else {
>> +		phys_addr_t __percpu *pbase;
>> +		int cpu;
>> +
>> +		for_each_possible_cpu(cpu) {
>> +			pbase = per_cpu_ptr(dbinfo->percpu_doorbells, cpu);
>> +			ret += compute_db_mapping_requirements(*pbase,
>> +							       dbinfo->size,
>> +							       order);
>> +		}
>> +	}
>> +	return ret;
>> +}
>> +
>> +int msi_doorbell_pages(unsigned int order)
>> +{
>> +	struct irqchip_doorbell *db;
>> +	int ret = 0;
>> +
>> +	mutex_lock(&irqchip_doorbell_mutex);
>> +	list_for_each_entry(db, &irqchip_doorbell_list, next) {
> 
> Pointless braces
> 
>> +		ret += compute_dbinfo_mapping_requirements(&db->info, order);
>> +	}
>> +	mutex_unlock(&irqchip_doorbell_mutex);
>> +
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(msi_doorbell_pages);
> 
> So here is a general rant about your naming choices.
> 
>    struct irqchip_doorbell
>    struct irq_chip_msi_doorbell_info
> 
>    struct irq_chip {
>    	  ....	  *(*msi_doorbell_info);
>    }
> 
>    irqchip_doorbell_mutex
> 
>    msi_doorbell_register_global
>    msi_doorbell_unregister_global
> 
>    msi_doorbell_pages
> 
> This really sucks. Your public functions start sensibly with msi_doorbell.
> 
> Though what is the _global postfix for the register/unregister functions for?
> Are there _private functions in the pipeline?
> 
> msi_doorbell_pages() is not telling me what it does. msi_calc_doorbell_pages()
> would describe it right away.
> 
> You doorbell info structure can really do with:
> 
>     struct msi_doorbell_info;
> 
> And the wrapper struct around it is fine with:
> 
>     struct msi_doorbell;
> 
> Thanks,
> 
> 	tglx
> 

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