CXL uncorrectable errors (UCE) will soon be handled separately from the PCI
AER handling. The merge_result() function can be made common to use in both
handling paths.

Rename the PCI subsystem's merge_result() to be pci_ers_merge_result().
Export pci_ers_merge_result() to make available for the CXL and other
drivers to use.

Update pci_ers_merge_result() to support recently introduced PCI_ERS_RESULT_PANIC
result.

Signed-off-by: Terry Bowman <terry.bowman@amd.com>

---
Changes in v10->v11:
- New patch
- pci_ers_merge_result() - Change export to non-namespace and rename
  to be pci_ers_merge_result()
- Move pci_ers_merge_result() definition to pci.h. Needs pci_ers_result
---
 drivers/pci/pcie/err.c | 14 +++++++++-----
 include/linux/pci.h    | 11 +++++++++++
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
index de6381c690f5..368bad0cb90e 100644
--- a/drivers/pci/pcie/err.c
+++ b/drivers/pci/pcie/err.c
@@ -21,9 +21,12 @@
 #include "portdrv.h"
 #include "../pci.h"
 
-static pci_ers_result_t merge_result(enum pci_ers_result orig,
-				  enum pci_ers_result new)
+pci_ers_result_t pci_ers_merge_result(enum pci_ers_result orig,
+				      enum pci_ers_result new)
 {
+	if (new == PCI_ERS_RESULT_PANIC)
+		return PCI_ERS_RESULT_PANIC;
+
 	if (new == PCI_ERS_RESULT_NO_AER_DRIVER)
 		return PCI_ERS_RESULT_NO_AER_DRIVER;
 
@@ -45,6 +48,7 @@ static pci_ers_result_t merge_result(enum pci_ers_result orig,
 
 	return orig;
 }
+EXPORT_SYMBOL(pci_ers_merge_result);
 
 static int report_error_detected(struct pci_dev *dev,
 				 pci_channel_state_t state,
@@ -81,7 +85,7 @@ static int report_error_detected(struct pci_dev *dev,
 		vote = err_handler->error_detected(dev, state);
 	}
 	pci_uevent_ers(dev, vote);
-	*result = merge_result(*result, vote);
+	*result = pci_ers_merge_result(*result, vote);
 	device_unlock(&dev->dev);
 	return 0;
 }
@@ -121,7 +125,7 @@ static int report_mmio_enabled(struct pci_dev *dev, void *data)
 
 	err_handler = pdrv->err_handler;
 	vote = err_handler->mmio_enabled(dev);
-	*result = merge_result(*result, vote);
+	*result = pci_ers_merge_result(*result, vote);
 out:
 	device_unlock(&dev->dev);
 	return 0;
@@ -140,7 +144,7 @@ static int report_slot_reset(struct pci_dev *dev, void *data)
 
 	err_handler = pdrv->err_handler;
 	vote = err_handler->slot_reset(dev);
-	*result = merge_result(*result, vote);
+	*result = pci_ers_merge_result(*result, vote);
 out:
 	device_unlock(&dev->dev);
 	return 0;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 3407d687459d..ff6812b2b9b6 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -2760,6 +2760,17 @@ static inline bool pci_is_thunderbolt_attached(struct pci_dev *pdev)
 void pci_uevent_ers(struct pci_dev *pdev, enum  pci_ers_result err_type);
 #endif
 
+#if defined(CONFIG_PCIEAER)
+pci_ers_result_t pci_ers_merge_result(enum pci_ers_result orig,
+				      enum pci_ers_result new);
+#else
+static inline pci_ers_result_t pci_ers_merge_result(enum pci_ers_result orig,
+						    enum pci_ers_result new)
+{
+	return PCI_ERS_RESULT_NONE;
+}
+#endif
+
 #include <linux/dma-mapping.h>
 
 #define pci_emerg(pdev, fmt, arg...)	dev_emerg(&(pdev)->dev, fmt, ##arg)
-- 
2.51.0.rc2.21.ge5ab6b3e5a

Hi Terry,

kernel test robot noticed the following build errors:

[auto build test ERROR on f11a5f89910a7ae970fbce4fdc02d86a8ba8570f]

url:    https://github.com/intel-lab-lkp/linux/commits/Terry-Bowman/cxl-Remove-ifdef-blocks-of-CONFIG_PCIEAER_CXL-from-core-pci-c/20250827-094257
base:   f11a5f89910a7ae970fbce4fdc02d86a8ba8570f
patch link:    https://lore.kernel.org/r/20250827013539.903682-21-terry.bowman%40amd.com
patch subject: [PATCH v11 20/23] CXL/PCI: Export and rename merge_result() to pci_ers_merge_result()
config: powerpc64-randconfig-002-20250827 (https://download.01.org/0day-ci/archive/20250827/202508271903.HTGgt8kV-lkp@intel.com/config)
compiler: powerpc64-linux-gcc (GCC) 11.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250827/202508271903.HTGgt8kV-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202508271903.HTGgt8kV-lkp@intel.com/

All errors (new ones prefixed by >>):

>> arch/powerpc/kernel/eeh_driver.c:68:28: error: redefinition of 'pci_ers_merge_result'
      68 | static enum pci_ers_result pci_ers_merge_result(enum pci_ers_result old,
         |                            ^~~~~~~~~~~~~~~~~~~~
   In file included from arch/powerpc/kernel/eeh_driver.c:13:
   include/linux/pci.h:2767:32: note: previous definition of 'pci_ers_merge_result' with type 'pci_ers_result_t(enum pci_ers_result,  enum pci_ers_result)' {aka 'unsigned int(enum pci_ers_result,  enum pci_ers_result)'}
    2767 | static inline pci_ers_result_t pci_ers_merge_result(enum pci_ers_result orig,
         |                                ^~~~~~~~~~~~~~~~~~~~


vim +/pci_ers_merge_result +68 arch/powerpc/kernel/eeh_driver.c

20b344971433da Sam Bobroff 2018-05-25  67  
30424e386a30d1 Sam Bobroff 2018-05-25 @68  static enum pci_ers_result pci_ers_merge_result(enum pci_ers_result old,
30424e386a30d1 Sam Bobroff 2018-05-25  69  						enum pci_ers_result new)
30424e386a30d1 Sam Bobroff 2018-05-25  70  {
30424e386a30d1 Sam Bobroff 2018-05-25  71  	if (eeh_result_priority(new) > eeh_result_priority(old))
30424e386a30d1 Sam Bobroff 2018-05-25  72  		return new;
30424e386a30d1 Sam Bobroff 2018-05-25  73  	return old;
30424e386a30d1 Sam Bobroff 2018-05-25  74  }
30424e386a30d1 Sam Bobroff 2018-05-25  75  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

On Tue, Aug 26, 2025 at 08:35:35PM -0500, Terry Bowman wrote:
> +++ b/include/linux/pci.h
> @@ -2760,6 +2760,17 @@ static inline bool pci_is_thunderbolt_attached(struct pci_dev *pdev)
>  void pci_uevent_ers(struct pci_dev *pdev, enum  pci_ers_result err_type);
>  #endif
>  
> +#if defined(CONFIG_PCIEAER)
> +pci_ers_result_t pci_ers_merge_result(enum pci_ers_result orig,
> +				      enum pci_ers_result new);
> +#else
> +static inline pci_ers_result_t pci_ers_merge_result(enum pci_ers_result orig,
> +						    enum pci_ers_result new)
> +{
> +	return PCI_ERS_RESULT_NONE;
> +}
> +#endif
> +
>  #include <linux/dma-mapping.h>
>  
>  #define pci_emerg(pdev, fmt, arg...)	dev_emerg(&(pdev)->dev, fmt, ##arg)

Would it be possible for you to just declare a local version of
pci_ers_merge_result() within drivers/cxl/ which is encapsulated by
"#ifndef CONFIG_PCIEAER"?

That would avoid the need to make this public in include/linux/pci.h.

Thanks,

Lukas

On 8/27/2025 3:04 AM, Lukas Wunner wrote:
> On Tue, Aug 26, 2025 at 08:35:35PM -0500, Terry Bowman wrote:
>> +++ b/include/linux/pci.h
>> @@ -2760,6 +2760,17 @@ static inline bool pci_is_thunderbolt_attached(struct pci_dev *pdev)
>>  void pci_uevent_ers(struct pci_dev *pdev, enum  pci_ers_result err_type);
>>  #endif
>>  
>> +#if defined(CONFIG_PCIEAER)
>> +pci_ers_result_t pci_ers_merge_result(enum pci_ers_result orig,
>> +				      enum pci_ers_result new);
>> +#else
>> +static inline pci_ers_result_t pci_ers_merge_result(enum pci_ers_result orig,
>> +						    enum pci_ers_result new)
>> +{
>> +	return PCI_ERS_RESULT_NONE;
>> +}
>> +#endif
>> +
>>  #include <linux/dma-mapping.h>
>>  
>>  #define pci_emerg(pdev, fmt, arg...)	dev_emerg(&(pdev)->dev, fmt, ##arg)
> Would it be possible for you to just declare a local version of
> pci_ers_merge_result() within drivers/cxl/ which is encapsulated by
> "#ifndef CONFIG_PCIEAER"?
>
> That would avoid the need to make this public in include/linux/pci.h.
>
> Thanks,
>
> Lukas
Hi Lukas,

The move of local merge_result() to exported pci_merge_result() was requested 
by Jonathan Cameron:
https://lore.kernel.org/linux-cxl/20250627120541.00003a14@huawei.com/

I believe the intent was to make reuse of the PCI merge function to keep the PCI 
and CXL UCE flows somewhat similar.

Jonathan may have a better explanation. I'm not opposed to either solution but 
adding details here for discussion with Jonathan.
 
Regards,
Terry

On Wed, Sep 10, 2025 at 10:57:17AM -0500, Bowman, Terry wrote:
> On 8/27/2025 3:04 AM, Lukas Wunner wrote:
> > On Tue, Aug 26, 2025 at 08:35:35PM -0500, Terry Bowman wrote:
> >> +++ b/include/linux/pci.h
> >> @@ -2760,6 +2760,17 @@ static inline bool pci_is_thunderbolt_attached(struct pci_dev *pdev)
> >>  void pci_uevent_ers(struct pci_dev *pdev, enum  pci_ers_result err_type);
> >>  #endif
> >>  
> >> +#if defined(CONFIG_PCIEAER)
> >> +pci_ers_result_t pci_ers_merge_result(enum pci_ers_result orig,
> >> +				      enum pci_ers_result new);
> >> +#else
> >> +static inline pci_ers_result_t pci_ers_merge_result(enum pci_ers_result orig,
> >> +						    enum pci_ers_result new)
> >> +{
> >> +	return PCI_ERS_RESULT_NONE;
> >> +}
> >> +#endif
> >> +
> >>  #include <linux/dma-mapping.h>
> >>  
> >>  #define pci_emerg(pdev, fmt, arg...)	dev_emerg(&(pdev)->dev, fmt, ##arg)
> > Would it be possible for you to just declare a local version of
> > pci_ers_merge_result() within drivers/cxl/ which is encapsulated by
> > "#ifndef CONFIG_PCIEAER"?
> >
> > That would avoid the need to make this public in include/linux/pci.h.
> 
> The move of local merge_result() to exported pci_merge_result() was requested
> by Jonathan Cameron:
> https://lore.kernel.org/linux-cxl/20250627120541.00003a14@huawei.com/
> 
> I believe the intent was to make reuse of the PCI merge function to keep the
> PCI and CXL UCE flows somewhat similar.

That's not my point.  My point is, can you avoid declaring the static inline
in include/linux/pci.h if you move it to drivers/cxl/ and encapsulate by
"#ifndef CONFIG_PCIEAER"?  I'm only referring to the static inline stub.

Thanks,

Lukas