Re: [PATCH v2] PCI/MSI: Simplify the return value of arch_setup_msi_irqs

[Bjorn Helgaas]

On Wed, Jun 22, 2016 at 11:20:20AM +0800, Shawn Lin wrote:
> No any callers do care whether arch_setup_msi_irqs returns
> -ENOSPC or other error numbers. That means they treat the
> negative numbers in the same way. So there shouldn't make any
> difference to directly return -ENOSPC if finding it's non-zero.

This return value gets returned all the way up to the external
interfaces used by drivers, e.g., pci_enable_msi_range(), so it would
take quite a lot of analysis to assert that *no* caller cares whether
it's -ENOSPC or something else.  I suspect you're right that it
probably doesn't matter, but it looks pretty hard to prove it.

> Signed-off-by: Shawn Lin 
> 
> ---
> 
> Changes in v2:
> - fix warning generated by -Wmisleading-indentation reported by Kbuild robot
> 
>  drivers/pci/msi.c | 6 ++
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
> index a080f44..5057219 100644
> --- a/drivers/pci/msi.c
> +++ b/drivers/pci/msi.c
> @@ -108,7 +108,7 @@ int __weak arch_setup_msi_irqs(struct pci_dev *dev, int 
> nvec, int type)
>  {
>   struct msi_controller *chip = dev->bus->msi;
>   struct msi_desc *entry;
> - int ret;
> + int ret = 0;

I don't think this initialization is necessary.

>   if (chip && chip->setup_irqs)
>   return chip->setup_irqs(chip, dev, nvec, type);
> @@ -121,9 +121,7 @@ int __weak arch_setup_msi_irqs(struct pci_dev *dev, int 
> nvec, int type)
>  
>   for_each_pci_msi_entry(entry, dev) {
>   ret = arch_setup_msi_irq(dev, entry);
> - if (ret < 0)
> - return ret;
> - if (ret > 0)
> + if (ret)
>   return -ENOSPC;
>   }
>  
> -- 
> 2.3.7
> 
> 
> --
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> the body of a message to majord...@vger.kernel.org
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Re: [PATCH v2] PCI/MSI: Simplify the return value of arch_setup_msi_irqs

[Bjorn Helgaas]

On Wed, Jun 22, 2016 at 11:20:20AM +0800, Shawn Lin wrote:
> No any callers do care whether arch_setup_msi_irqs returns
> -ENOSPC or other error numbers. That means they treat the
> negative numbers in the same way. So there shouldn't make any
> difference to directly return -ENOSPC if finding it's non-zero.

This return value gets returned all the way up to the external
interfaces used by drivers, e.g., pci_enable_msi_range(), so it would
take quite a lot of analysis to assert that *no* caller cares whether
it's -ENOSPC or something else.  I suspect you're right that it
probably doesn't matter, but it looks pretty hard to prove it.

> Signed-off-by: Shawn Lin 
> 
> ---
> 
> Changes in v2:
> - fix warning generated by -Wmisleading-indentation reported by Kbuild robot
> 
>  drivers/pci/msi.c | 6 ++
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
> index a080f44..5057219 100644
> --- a/drivers/pci/msi.c
> +++ b/drivers/pci/msi.c
> @@ -108,7 +108,7 @@ int __weak arch_setup_msi_irqs(struct pci_dev *dev, int 
> nvec, int type)
>  {
>   struct msi_controller *chip = dev->bus->msi;
>   struct msi_desc *entry;
> - int ret;
> + int ret = 0;

I don't think this initialization is necessary.

>   if (chip && chip->setup_irqs)
>   return chip->setup_irqs(chip, dev, nvec, type);
> @@ -121,9 +121,7 @@ int __weak arch_setup_msi_irqs(struct pci_dev *dev, int 
> nvec, int type)
>  
>   for_each_pci_msi_entry(entry, dev) {
>   ret = arch_setup_msi_irq(dev, entry);
> - if (ret < 0)
> - return ret;
> - if (ret > 0)
> + if (ret)
>   return -ENOSPC;
>   }
>  
> -- 
> 2.3.7
> 
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-pci" in
> the body of a message to majord...@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

[PATCH v2] PCI/MSI: Simplify the return value of arch_setup_msi_irqs

[Shawn Lin]

No any callers do care whether arch_setup_msi_irqs returns
-ENOSPC or other error numbers. That means they treat the
negative numbers in the same way. So there shouldn't make any
difference to directly return -ENOSPC if finding it's non-zero.

Signed-off-by: Shawn Lin 

---

Changes in v2:
- fix warning generated by -Wmisleading-indentation reported by Kbuild robot

 drivers/pci/msi.c | 6 ++
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index a080f44..5057219 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -108,7 +108,7 @@ int __weak arch_setup_msi_irqs(struct pci_dev *dev, int 
nvec, int type)
 {
struct msi_controller *chip = dev->bus->msi;
struct msi_desc *entry;
-   int ret;
+   int ret = 0;
 
if (chip && chip->setup_irqs)
return chip->setup_irqs(chip, dev, nvec, type);
@@ -121,9 +121,7 @@ int __weak arch_setup_msi_irqs(struct pci_dev *dev, int 
nvec, int type)
 
for_each_pci_msi_entry(entry, dev) {
ret = arch_setup_msi_irq(dev, entry);
-   if (ret < 0)
-   return ret;
-   if (ret > 0)
+   if (ret)
return -ENOSPC;
}
 
-- 
2.3.7

[PATCH v2] PCI/MSI: Simplify the return value of arch_setup_msi_irqs

[Shawn Lin]

No any callers do care whether arch_setup_msi_irqs returns
-ENOSPC or other error numbers. That means they treat the
negative numbers in the same way. So there shouldn't make any
difference to directly return -ENOSPC if finding it's non-zero.

Signed-off-by: Shawn Lin 

---

Changes in v2:
- fix warning generated by -Wmisleading-indentation reported by Kbuild robot

 drivers/pci/msi.c | 6 ++
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index a080f44..5057219 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -108,7 +108,7 @@ int __weak arch_setup_msi_irqs(struct pci_dev *dev, int 
nvec, int type)
 {
struct msi_controller *chip = dev->bus->msi;
struct msi_desc *entry;
-   int ret;
+   int ret = 0;
 
if (chip && chip->setup_irqs)
return chip->setup_irqs(chip, dev, nvec, type);
@@ -121,9 +121,7 @@ int __weak arch_setup_msi_irqs(struct pci_dev *dev, int 
nvec, int type)
 
for_each_pci_msi_entry(entry, dev) {
ret = arch_setup_msi_irq(dev, entry);
-   if (ret < 0)
-   return ret;
-   if (ret > 0)
+   if (ret)
return -ENOSPC;
}
 
-- 
2.3.7