[RESEND PATCH] PCI: Factor functions of PCI function reset

[RESEND PATCH] PCI: Factor functions of PCI function reset

[Yicong Yang]

Previosly we use pci_probe_reset_function() to probe whehter a function
can be reset and use __pci_reset_function_locked() to perform a function
reset. These two functions have lots of common lines.

Factor the two functions and reduce the redundancy.

Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
---
 drivers/pci/pci.c   | 61 ++++++++++++++++-------------------------------------
 drivers/pci/pci.h   |  2 +-
 drivers/pci/probe.c |  2 +-
 3 files changed, 20 insertions(+), 45 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index e39c549..e3e5f0f 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5006,9 +5006,11 @@ static void pci_dev_restore(struct pci_dev *dev)
 }

 /**
- * __pci_reset_function_locked - reset a PCI device function while holding
- * the @dev mutex lock.
+ * pci_probe_reset_function - check whether the device can be safely reset
+ *                            or reset a PCI device function while holding
+ *                            the @dev mutex lock.
  * @dev: PCI device to reset
+ * @probe: Probe or not whether the device can be reset.
  *
  * Some devices allow an individual function to be reset without affecting
  * other functions in the same device.  The PCI device must be responsive
@@ -5022,10 +5024,10 @@ static void pci_dev_restore(struct pci_dev *dev)
  * device including MSI, bus mastering, BARs, decoding IO and memory spaces,
  * etc.
  *
- * Returns 0 if the device function was successfully reset or negative if the
- * device doesn't support resetting a single function.
+ * Returns 0 if the device function can be reset or was successfully reset.
+ * negative if the device doesn't support resetting a single function.
  */
-int __pci_reset_function_locked(struct pci_dev *dev)
+int pci_probe_reset_function(struct pci_dev *dev, int probe)
 {
 	int rc;

@@ -5039,61 +5041,34 @@ int __pci_reset_function_locked(struct pci_dev *dev)
 	 * other error, we're also finished: this indicates that further
 	 * reset mechanisms might be broken on the device.
 	 */
-	rc = pci_dev_specific_reset(dev, 0);
+	rc = pci_dev_specific_reset(dev, probe);
 	if (rc != -ENOTTY)
 		return rc;
 	if (pcie_has_flr(dev)) {
+		if (probe)
+			return 0;
 		rc = pcie_flr(dev);
 		if (rc != -ENOTTY)
 			return rc;
 	}
-	rc = pci_af_flr(dev, 0);
+	rc = pci_af_flr(dev, probe);
 	if (rc != -ENOTTY)
 		return rc;
-	rc = pci_pm_reset(dev, 0);
+	rc = pci_pm_reset(dev, probe);
 	if (rc != -ENOTTY)
 		return rc;
-	rc = pci_dev_reset_slot_function(dev, 0);
+	rc = pci_dev_reset_slot_function(dev, probe);
 	if (rc != -ENOTTY)
 		return rc;
-	return pci_parent_bus_reset(dev, 0);
+
+	return pci_parent_bus_reset(dev, probe);
 }
-EXPORT_SYMBOL_GPL(__pci_reset_function_locked);

-/**
- * pci_probe_reset_function - check whether the device can be safely reset
- * @dev: PCI device to reset
- *
- * Some devices allow an individual function to be reset without affecting
- * other functions in the same device.  The PCI device must be responsive
- * to PCI config space in order to use this function.
- *
- * Returns 0 if the device function can be reset or negative if the
- * device doesn't support resetting a single function.
- */
-int pci_probe_reset_function(struct pci_dev *dev)
+int __pci_reset_function_locked(struct pci_dev *dev)
 {
-	int rc;
-
-	might_sleep();
-
-	rc = pci_dev_specific_reset(dev, 1);
-	if (rc != -ENOTTY)
-		return rc;
-	if (pcie_has_flr(dev))
-		return 0;
-	rc = pci_af_flr(dev, 1);
-	if (rc != -ENOTTY)
-		return rc;
-	rc = pci_pm_reset(dev, 1);
-	if (rc != -ENOTTY)
-		return rc;
-	rc = pci_dev_reset_slot_function(dev, 1);
-	if (rc != -ENOTTY)
-		return rc;
-
-	return pci_parent_bus_reset(dev, 1);
+	return pci_probe_reset_function(dev, 0);
 }
+EXPORT_SYMBOL_GPL(__pci_reset_function_locked);

 /**
  * pci_reset_function - quiesce and reset a PCI device function
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index fa12f7c..73740dd 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -39,7 +39,7 @@ enum pci_mmap_api {
 int pci_mmap_fits(struct pci_dev *pdev, int resno, struct vm_area_struct *vmai,
 		  enum pci_mmap_api mmap_api);

-int pci_probe_reset_function(struct pci_dev *dev);
+int pci_probe_reset_function(struct pci_dev *dev, int probe);
 int pci_bridge_secondary_bus_reset(struct pci_dev *dev);
 int pci_bus_error_reset(struct pci_dev *dev);

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 03d3712..793cc8a 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2403,7 +2403,7 @@ static void pci_init_capabilities(struct pci_dev *dev)

 	pcie_report_downtraining(dev);

-	if (pci_probe_reset_function(dev) == 0)
+	if (pci_probe_reset_function(dev, 1) == 0)
 		dev->reset_fn = 1;
 }

--
2.8.1

Re: [RESEND PATCH] PCI: Factor functions of PCI function reset

[Krzysztof Wilczyński]

Hi,

[...]
> + * Returns 0 if the device function can be reset or was successfully reset.
> + * negative if the device doesn't support resetting a single function.
[...]

A small nitpick, so feel free to ignore it, of course.  A little change
to the above sentence:

  Returns 0 if the device function can be reset or was successfully
  reset, otherwise negative if the device doesn't support resetting
  a single function.

What do you think?

Krzysztof

Re: [RESEND PATCH] PCI: Factor functions of PCI function reset

[Yicong Yang]

Hi Krzysztof,

thanks for picking up this.

On 2021/3/8 7:56, Krzysztof Wilczyński wrote:
> Hi,
> 
> [...]
>> + * Returns 0 if the device function can be reset or was successfully reset.
>> + * negative if the device doesn't support resetting a single function.
> [...]
> 
> A small nitpick, so feel free to ignore it, of course.  A little change
> to the above sentence:
> 
>   Returns 0 if the device function can be reset or was successfully
>   reset, otherwise negative if the device doesn't support resetting
>   a single function.
> 
> What do you think?
> 

sure. any other comments on the patch? otherwise i'd like to post a v2 one
according to your suggestion. :)

Regards,
Yicong

Re: [RESEND PATCH] PCI: Factor functions of PCI function reset

[Bjorn Helgaas]

[+cc Alex, Krzysztof]

On Wed, Nov 11, 2020 at 06:22:03PM +0800, Yicong Yang wrote:
> Previosly we use pci_probe_reset_function() to probe whehter a function
> can be reset and use __pci_reset_function_locked() to perform a function
> reset. These two functions have lots of common lines.

s/Previosly/Previously/
s/we use/we used/
s/whehter/whether/

I'm not a big fan of dual-purpose functions that decide whether to
probe or to reset based on a parameter.  Those two things just don't
seem semantically compatible.  But I do see your point about common
lines, and the underlying functions (pci_dev_specific_reset(),
pci_af_flr(), etc) already have that structure.

Let me think about this some more.

> Factor the two functions and reduce the redundancy.
> 
> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
> ---
>  drivers/pci/pci.c   | 61 ++++++++++++++++-------------------------------------
>  drivers/pci/pci.h   |  2 +-
>  drivers/pci/probe.c |  2 +-
>  3 files changed, 20 insertions(+), 45 deletions(-)
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index e39c549..e3e5f0f 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -5006,9 +5006,11 @@ static void pci_dev_restore(struct pci_dev *dev)
>  }
> 
>  /**
> - * __pci_reset_function_locked - reset a PCI device function while holding
> - * the @dev mutex lock.
> + * pci_probe_reset_function - check whether the device can be safely reset
> + *                            or reset a PCI device function while holding
> + *                            the @dev mutex lock.
>   * @dev: PCI device to reset
> + * @probe: Probe or not whether the device can be reset.
>   *
>   * Some devices allow an individual function to be reset without affecting
>   * other functions in the same device.  The PCI device must be responsive
> @@ -5022,10 +5024,10 @@ static void pci_dev_restore(struct pci_dev *dev)
>   * device including MSI, bus mastering, BARs, decoding IO and memory spaces,
>   * etc.
>   *
> - * Returns 0 if the device function was successfully reset or negative if the
> - * device doesn't support resetting a single function.
> + * Returns 0 if the device function can be reset or was successfully reset.
> + * negative if the device doesn't support resetting a single function.
>   */
> -int __pci_reset_function_locked(struct pci_dev *dev)
> +int pci_probe_reset_function(struct pci_dev *dev, int probe)
>  {
>  	int rc;
> 
> @@ -5039,61 +5041,34 @@ int __pci_reset_function_locked(struct pci_dev *dev)
>  	 * other error, we're also finished: this indicates that further
>  	 * reset mechanisms might be broken on the device.
>  	 */
> -	rc = pci_dev_specific_reset(dev, 0);
> +	rc = pci_dev_specific_reset(dev, probe);
>  	if (rc != -ENOTTY)
>  		return rc;
>  	if (pcie_has_flr(dev)) {
> +		if (probe)
> +			return 0;
>  		rc = pcie_flr(dev);
>  		if (rc != -ENOTTY)
>  			return rc;
>  	}
> -	rc = pci_af_flr(dev, 0);
> +	rc = pci_af_flr(dev, probe);
>  	if (rc != -ENOTTY)
>  		return rc;
> -	rc = pci_pm_reset(dev, 0);
> +	rc = pci_pm_reset(dev, probe);
>  	if (rc != -ENOTTY)
>  		return rc;
> -	rc = pci_dev_reset_slot_function(dev, 0);
> +	rc = pci_dev_reset_slot_function(dev, probe);
>  	if (rc != -ENOTTY)
>  		return rc;
> -	return pci_parent_bus_reset(dev, 0);
> +
> +	return pci_parent_bus_reset(dev, probe);
>  }
> -EXPORT_SYMBOL_GPL(__pci_reset_function_locked);
> 
> -/**
> - * pci_probe_reset_function - check whether the device can be safely reset
> - * @dev: PCI device to reset
> - *
> - * Some devices allow an individual function to be reset without affecting
> - * other functions in the same device.  The PCI device must be responsive
> - * to PCI config space in order to use this function.
> - *
> - * Returns 0 if the device function can be reset or negative if the
> - * device doesn't support resetting a single function.
> - */
> -int pci_probe_reset_function(struct pci_dev *dev)
> +int __pci_reset_function_locked(struct pci_dev *dev)
>  {
> -	int rc;
> -
> -	might_sleep();
> -
> -	rc = pci_dev_specific_reset(dev, 1);
> -	if (rc != -ENOTTY)
> -		return rc;
> -	if (pcie_has_flr(dev))
> -		return 0;
> -	rc = pci_af_flr(dev, 1);
> -	if (rc != -ENOTTY)
> -		return rc;
> -	rc = pci_pm_reset(dev, 1);
> -	if (rc != -ENOTTY)
> -		return rc;
> -	rc = pci_dev_reset_slot_function(dev, 1);
> -	if (rc != -ENOTTY)
> -		return rc;
> -
> -	return pci_parent_bus_reset(dev, 1);
> +	return pci_probe_reset_function(dev, 0);
>  }
> +EXPORT_SYMBOL_GPL(__pci_reset_function_locked);
> 
>  /**
>   * pci_reset_function - quiesce and reset a PCI device function
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index fa12f7c..73740dd 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -39,7 +39,7 @@ enum pci_mmap_api {
>  int pci_mmap_fits(struct pci_dev *pdev, int resno, struct vm_area_struct *vmai,
>  		  enum pci_mmap_api mmap_api);
> 
> -int pci_probe_reset_function(struct pci_dev *dev);
> +int pci_probe_reset_function(struct pci_dev *dev, int probe);
>  int pci_bridge_secondary_bus_reset(struct pci_dev *dev);
>  int pci_bus_error_reset(struct pci_dev *dev);
> 
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 03d3712..793cc8a 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -2403,7 +2403,7 @@ static void pci_init_capabilities(struct pci_dev *dev)
> 
>  	pcie_report_downtraining(dev);
> 
> -	if (pci_probe_reset_function(dev) == 0)
> +	if (pci_probe_reset_function(dev, 1) == 0)
>  		dev->reset_fn = 1;
>  }
> 
> --
> 2.8.1
> 

Re: [RESEND PATCH] PCI: Factor functions of PCI function reset

[Yicong Yang]

On 2021/3/9 23:50, Bjorn Helgaas wrote:
> [+cc Alex, Krzysztof]
> 
> On Wed, Nov 11, 2020 at 06:22:03PM +0800, Yicong Yang wrote:
>> Previosly we use pci_probe_reset_function() to probe whehter a function
>> can be reset and use __pci_reset_function_locked() to perform a function
>> reset. These two functions have lots of common lines.
> 
> s/Previosly/Previously/
> s/we use/we used/
> s/whehter/whether/

will fix.

> 
> I'm not a big fan of dual-purpose functions that decide whether to
> probe or to reset based on a parameter.  Those two things just don't
> seem semantically compatible.  But I do see your point about common
> lines, and the underlying functions (pci_dev_specific_reset(),
> pci_af_flr(), etc) already have that structure.
> 

i noticed this when i tried to fix another issue with FLR[1]. as you said, the underlying
functions use the probe flag to indicate whether it is a probe operation or not
and i think it make sense to reduce the redundency in the same way.


> Let me think about this some more.
> 

sure, of course.

It's also very kind to have any comments on the previous issue we met:
[1] https://lore.kernel.org/linux-pci/1605090088-13960-1-git-send-email-yangyicong@hisilicon.com/

Thanks,
Yicong

>> Factor the two functions and reduce the redundancy.
>>
>> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
>> ---
>>  drivers/pci/pci.c   | 61 ++++++++++++++++-------------------------------------
>>  drivers/pci/pci.h   |  2 +-
>>  drivers/pci/probe.c |  2 +-
>>  3 files changed, 20 insertions(+), 45 deletions(-)
>>
>> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
>> index e39c549..e3e5f0f 100644
>> --- a/drivers/pci/pci.c
>> +++ b/drivers/pci/pci.c
>> @@ -5006,9 +5006,11 @@ static void pci_dev_restore(struct pci_dev *dev)
>>  }
>>
>>  /**
>> - * __pci_reset_function_locked - reset a PCI device function while holding
>> - * the @dev mutex lock.
>> + * pci_probe_reset_function - check whether the device can be safely reset
>> + *                            or reset a PCI device function while holding
>> + *                            the @dev mutex lock.
>>   * @dev: PCI device to reset
>> + * @probe: Probe or not whether the device can be reset.
>>   *
>>   * Some devices allow an individual function to be reset without affecting
>>   * other functions in the same device.  The PCI device must be responsive
>> @@ -5022,10 +5024,10 @@ static void pci_dev_restore(struct pci_dev *dev)
>>   * device including MSI, bus mastering, BARs, decoding IO and memory spaces,
>>   * etc.
>>   *
>> - * Returns 0 if the device function was successfully reset or negative if the
>> - * device doesn't support resetting a single function.
>> + * Returns 0 if the device function can be reset or was successfully reset.
>> + * negative if the device doesn't support resetting a single function.
>>   */
>> -int __pci_reset_function_locked(struct pci_dev *dev)
>> +int pci_probe_reset_function(struct pci_dev *dev, int probe)
>>  {
>>  	int rc;
>>
>> @@ -5039,61 +5041,34 @@ int __pci_reset_function_locked(struct pci_dev *dev)
>>  	 * other error, we're also finished: this indicates that further
>>  	 * reset mechanisms might be broken on the device.
>>  	 */
>> -	rc = pci_dev_specific_reset(dev, 0);
>> +	rc = pci_dev_specific_reset(dev, probe);
>>  	if (rc != -ENOTTY)
>>  		return rc;
>>  	if (pcie_has_flr(dev)) {
>> +		if (probe)
>> +			return 0;
>>  		rc = pcie_flr(dev);
>>  		if (rc != -ENOTTY)
>>  			return rc;
>>  	}
>> -	rc = pci_af_flr(dev, 0);
>> +	rc = pci_af_flr(dev, probe);
>>  	if (rc != -ENOTTY)
>>  		return rc;
>> -	rc = pci_pm_reset(dev, 0);
>> +	rc = pci_pm_reset(dev, probe);
>>  	if (rc != -ENOTTY)
>>  		return rc;
>> -	rc = pci_dev_reset_slot_function(dev, 0);
>> +	rc = pci_dev_reset_slot_function(dev, probe);
>>  	if (rc != -ENOTTY)
>>  		return rc;
>> -	return pci_parent_bus_reset(dev, 0);
>> +
>> +	return pci_parent_bus_reset(dev, probe);
>>  }
>> -EXPORT_SYMBOL_GPL(__pci_reset_function_locked);
>>
>> -/**
>> - * pci_probe_reset_function - check whether the device can be safely reset
>> - * @dev: PCI device to reset
>> - *
>> - * Some devices allow an individual function to be reset without affecting
>> - * other functions in the same device.  The PCI device must be responsive
>> - * to PCI config space in order to use this function.
>> - *
>> - * Returns 0 if the device function can be reset or negative if the
>> - * device doesn't support resetting a single function.
>> - */
>> -int pci_probe_reset_function(struct pci_dev *dev)
>> +int __pci_reset_function_locked(struct pci_dev *dev)
>>  {
>> -	int rc;
>> -
>> -	might_sleep();
>> -
>> -	rc = pci_dev_specific_reset(dev, 1);
>> -	if (rc != -ENOTTY)
>> -		return rc;
>> -	if (pcie_has_flr(dev))
>> -		return 0;
>> -	rc = pci_af_flr(dev, 1);
>> -	if (rc != -ENOTTY)
>> -		return rc;
>> -	rc = pci_pm_reset(dev, 1);
>> -	if (rc != -ENOTTY)
>> -		return rc;
>> -	rc = pci_dev_reset_slot_function(dev, 1);
>> -	if (rc != -ENOTTY)
>> -		return rc;
>> -
>> -	return pci_parent_bus_reset(dev, 1);
>> +	return pci_probe_reset_function(dev, 0);
>>  }
>> +EXPORT_SYMBOL_GPL(__pci_reset_function_locked);
>>
>>  /**
>>   * pci_reset_function - quiesce and reset a PCI device function
>> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
>> index fa12f7c..73740dd 100644
>> --- a/drivers/pci/pci.h
>> +++ b/drivers/pci/pci.h
>> @@ -39,7 +39,7 @@ enum pci_mmap_api {
>>  int pci_mmap_fits(struct pci_dev *pdev, int resno, struct vm_area_struct *vmai,
>>  		  enum pci_mmap_api mmap_api);
>>
>> -int pci_probe_reset_function(struct pci_dev *dev);
>> +int pci_probe_reset_function(struct pci_dev *dev, int probe);
>>  int pci_bridge_secondary_bus_reset(struct pci_dev *dev);
>>  int pci_bus_error_reset(struct pci_dev *dev);
>>
>> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
>> index 03d3712..793cc8a 100644
>> --- a/drivers/pci/probe.c
>> +++ b/drivers/pci/probe.c
>> @@ -2403,7 +2403,7 @@ static void pci_init_capabilities(struct pci_dev *dev)
>>
>>  	pcie_report_downtraining(dev);
>>
>> -	if (pci_probe_reset_function(dev) == 0)
>> +	if (pci_probe_reset_function(dev, 1) == 0)
>>  		dev->reset_fn = 1;
>>  }
>>
>> --
>> 2.8.1
>>
> 
> .
>