Re: [Patch Part2 v4 19/31] PCI/MSI: Simplify PCI MSI code by initializing msi_desc.nvec_used earlier

[Bjorn Helgaas <bhelgaas@google.com>]

On Tue, Nov 04, 2014 at 08:01:53PM +0800, Jiang Liu wrote:

  PCI/MSI: Initialize msi_desc.nvec_used earlier to simplify code

> Simplify PCI MSI code by initializing msi_desc.nvec_used and
> msi_desc.msi_attrib.mutiple when create MSI descriptors.

multiple
when creating

> Also remove redundant checks in IRQ remapping drivers, PCI MSI core
> already guarattees these.

guarantees

> Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

> ---
>  drivers/iommu/irq_remapping.c |    8 --------
>  drivers/pci/msi.c             |   40 +++++++++++++++-------------------------
>  2 files changed, 15 insertions(+), 33 deletions(-)
> 
> diff --git a/drivers/iommu/irq_remapping.c b/drivers/iommu/irq_remapping.c
> index 176ff4372b7d..32fe5b1322d0 100644
> --- a/drivers/iommu/irq_remapping.c
> +++ b/drivers/iommu/irq_remapping.c
> @@ -69,19 +69,13 @@ static int do_setup_msi_irqs(struct pci_dev *dev, int nvec)
>  	unsigned int irq;
>  	struct msi_desc *msidesc;
>  
> -	WARN_ON(!list_is_singular(&dev->msi_list));
>  	msidesc = list_entry(dev->msi_list.next, struct msi_desc, list);
> -	WARN_ON(msidesc->irq);
> -	WARN_ON(msidesc->msi_attrib.multiple);
> -	WARN_ON(msidesc->nvec_used);
>  
>  	irq = irq_alloc_hwirqs(nvec, dev_to_node(&dev->dev));
>  	if (irq == 0)
>  		return -ENOSPC;
>  
>  	nvec_pow2 = __roundup_pow_of_two(nvec);
> -	msidesc->nvec_used = nvec;
> -	msidesc->msi_attrib.multiple = ilog2(nvec_pow2);
>  	for (sub_handle = 0; sub_handle < nvec; sub_handle++) {
>  		if (!sub_handle) {
>  			index = msi_alloc_remapped_irq(dev, irq, nvec_pow2);
> @@ -109,8 +103,6 @@ error:
>  	 * IRQs from tearing down again in default_teardown_msi_irqs()
>  	 */
>  	msidesc->irq = 0;
> -	msidesc->nvec_used = 0;
> -	msidesc->msi_attrib.multiple = 0;
>  
>  	return ret;
>  }
> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
> index fb2ccb536324..afe974600c7d 100644
> --- a/drivers/pci/msi.c
> +++ b/drivers/pci/msi.c
> @@ -85,19 +85,13 @@ int __weak arch_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
>   */
>  void default_teardown_msi_irqs(struct pci_dev *dev)
>  {
> +	int i;
>  	struct msi_desc *entry;
>  
> -	list_for_each_entry(entry, &dev->msi_list, list) {
> -		int i, nvec;
> -		if (entry->irq == 0)
> -			continue;
> -		if (entry->nvec_used)
> -			nvec = entry->nvec_used;
> -		else
> -			nvec = 1 << entry->msi_attrib.multiple;
> -		for (i = 0; i < nvec; i++)
> -			arch_teardown_msi_irq(entry->irq + i);
> -	}
> +	list_for_each_entry(entry, &dev->msi_list, list)
> +		if (entry->irq)
> +			for (i = 0; i < entry->nvec_used; i++)
> +				arch_teardown_msi_irq(entry->irq + i);
>  }
>  
>  void __weak arch_teardown_msi_irqs(struct pci_dev *dev)
> @@ -353,19 +347,12 @@ static void free_msi_irqs(struct pci_dev *dev)
>  	struct msi_desc *entry, *tmp;
>  	struct attribute **msi_attrs;
>  	struct device_attribute *dev_attr;
> -	int count = 0;
> +	int i, count = 0;
>  
> -	list_for_each_entry(entry, &dev->msi_list, list) {
> -		int i, nvec;
> -		if (!entry->irq)
> -			continue;
> -		if (entry->nvec_used)
> -			nvec = entry->nvec_used;
> -		else
> -			nvec = 1 << entry->msi_attrib.multiple;
> -		for (i = 0; i < nvec; i++)
> -			BUG_ON(irq_has_action(entry->irq + i));
> -	}
> +	list_for_each_entry(entry, &dev->msi_list, list)
> +		if (entry->irq)
> +			for (i = 0; i < entry->nvec_used; i++)
> +				BUG_ON(irq_has_action(entry->irq + i));
>  
>  	arch_teardown_msi_irqs(dev);
>  
> @@ -556,7 +543,7 @@ error_attrs:
>  	return ret;
>  }
>  
> -static struct msi_desc *msi_setup_entry(struct pci_dev *dev)
> +static struct msi_desc *msi_setup_entry(struct pci_dev *dev, int nvec)
>  {
>  	u16 control;
>  	struct msi_desc *entry;
> @@ -574,6 +561,8 @@ static struct msi_desc *msi_setup_entry(struct pci_dev *dev)
>  	entry->msi_attrib.maskbit	= !!(control & PCI_MSI_FLAGS_MASKBIT);
>  	entry->msi_attrib.default_irq	= dev->irq;	/* Save IOAPIC IRQ */
>  	entry->msi_attrib.multi_cap	= (control & PCI_MSI_FLAGS_QMASK) >> 1;
> +	entry->msi_attrib.multiple	= ilog2(__roundup_pow_of_two(nvec));
> +	entry->nvec_used		= nvec;
>  
>  	if (control & PCI_MSI_FLAGS_64BIT)
>  		entry->mask_pos = dev->msi_cap + PCI_MSI_MASK_64;
> @@ -606,7 +595,7 @@ static int msi_capability_init(struct pci_dev *dev, int nvec)
>  
>  	msi_set_enable(dev, 0);	/* Disable MSI during set up */
>  
> -	entry = msi_setup_entry(dev);
> +	entry = msi_setup_entry(dev, nvec);
>  	if (!entry)
>  		return -ENOMEM;
>  
> @@ -677,6 +666,7 @@ static int msix_setup_entries(struct pci_dev *dev, void __iomem *base,
>  		entry->msi_attrib.entry_nr	= entries[i].entry;
>  		entry->msi_attrib.default_irq	= dev->irq;
>  		entry->mask_base		= base;
> +		entry->nvec_used		= 1;
>  
>  		list_add_tail(&entry->list, &dev->msi_list);
>  	}
> -- 
> 1.7.10.4
>