[PATCH 01/11] powerpc/powernv/ioda: Fix ref count for devices with their own PE

[Frederic Barrat]

Le 26/09/2019 à 18:44, Andrew Donnellan a écrit :
> On 9/9/19 5:45 pm, Frederic Barrat wrote:
>> Taking a reference on the pci_dev structure was required with initial
>> commit 184cd4a3b962 ("powerpc/powernv: PCI support for p7IOC under
>> OPAL v2"), where we were storing the pci_dev in the pci_dn structure.
>>
>> However, the pci_dev was later removed from the pci_dn structure, but
>> the reference was kept. See commit 902bdc57451c ("powerpc/powernv/idoa:
>> Remove unnecessary pcidev from pci_dn").
>>
>> The pnv_ioda_pe structure life cycle is the same as the pci_dev
>> structure, the PE is freed when the device is released. So we don't
>> need a reference for the pci_dev stored in the PE, otherwise the
>> pci_dev will never be released. Which is not really a surprise as the
>> comment (removed here as no longer needed) was stating as much.
>>
>> Fixes: 902bdc57451c ("powerpc/powernv/idoa: Remove unnecessary pcidev 
>> from pci_dn")
>> Signed-off-by: Frederic Barrat <fbarrat at linux.ibm.com>
>> ---
>>   arch/powerpc/platforms/powernv/pci-ioda.c | 11 +----------
>>   1 file changed, 1 insertion(+), 10 deletions(-)
>>
>> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c 
>> b/arch/powerpc/platforms/powernv/pci-ioda.c
>> index d8080558d020..92767f006f20 100644
>> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
>> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
>> @@ -1062,14 +1062,6 @@ static struct pnv_ioda_pe 
>> *pnv_ioda_setup_dev_PE(struct pci_dev *dev)
>>           return NULL;
>>       }
>> -    /* NOTE: We get only one ref to the pci_dev for the pdn, not for the
>> -     * pointer in the PE data structure, both should be destroyed at the
>> -     * same time. However, this needs to be looked at more closely again
>> -     * once we actually start removing things (Hotplug, SR-IOV, ...)
>> -     *
>> -     * At some point we want to remove the PDN completely anyways
>> -     */
>> -    pci_dev_get(dev);
>>       pdn->pe_number = pe->pe_number;
>>       pe->flags = PNV_IODA_PE_DEV;
>>       pe->pdev = dev;
>> @@ -1084,7 +1076,6 @@ static struct pnv_ioda_pe 
>> *pnv_ioda_setup_dev_PE(struct pci_dev *dev)
>>           pnv_ioda_free_pe(pe);
>>           pdn->pe_number = IODA_INVALID_PE;
>>           pe->pdev = NULL;
>> -        pci_dev_put(dev);
>>           return NULL;
>>       }
>> @@ -1228,7 +1219,7 @@ static struct pnv_ioda_pe 
>> *pnv_ioda_setup_npu_PE(struct pci_dev *npu_pdev)
>>                */
>>               dev_info(&npu_pdev->dev,
>>                   "Associating to existing PE %x\n", pe_num);
>> -            pci_dev_get(npu_pdev);
>> +            pci_dev_get(npu_pdev); // still needed after 902bdc57451c ?
> 
> Did you mean to leave that comment in?

Yes, I assumed the series wouldn't get in on the first try and a 
nvlink-minded developer would weigh in :)

   Fred


>>               npu_pdn = pci_get_pdn(npu_pdev);
>>               rid = npu_pdev->bus->number << 8 | npu_pdn->devfn;
>>               npu_pdn->pe_number = pe_num;
>>
>