Re: [PATCH net] PCI: fix the return value for the pci_find_pcie_root_port()

[Ding Tianhong]

On 2017/8/17 21:30, Thierry Reding wrote:
> On Thu, Aug 17, 2017 at 08:40:16PM +0800, Ding Tianhong wrote:
>>
>>
>> On 2017/8/17 18:51, Thierry Reding wrote:
>>> On Thu, Aug 17, 2017 at 10:25:30AM +0800, Ding Tianhong wrote:
 The pci_find_pcie_root_port() would return NULL if the given
 dev is already a Root Port, it looks like unfriendly to the
 PCIe Root Port device, Thierry and Bjorn suggest to let this
 function return the given dev under this circumstances.

 Fixes: 0e405232871d6 ("PCI: fix oops when try to find Root Port for a PCI 
 device")
 Suggested-by: Thierry Reding 
 Suggested-by: Bjorn Helgaas 
 Signed-off-by: Thierry Reding 
 Signed-off-by: Ding Tianhong 
 ---
  drivers/pci/pci.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

 diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
 index 7e2022f..352bb53 100644
 --- a/drivers/pci/pci.c
 +++ b/drivers/pci/pci.c
 @@ -514,7 +514,7 @@ struct resource *pci_find_resource(struct pci_dev 
 *dev, struct resource *res)
   */
  struct pci_dev *pci_find_pcie_root_port(struct pci_dev *dev)
  {
 -  struct pci_dev *bridge, *highest_pcie_bridge = NULL;
 +  struct pci_dev *bridge, *highest_pcie_bridge = dev;
  
bridge = pci_upstream_bridge(dev);
while (bridge && pci_is_pcie(bridge)) {
>>>
>>> I think this should actually be this change on top of a revert of commit
>>> 0e405232871d6 ("PCI: fix oops when try to find Root Port for a PCI
>>> device"). After the above change, the previous fix will have a redundant
>>> check because highest_pcie_bridge will never be NULL.
>>>
>>> Let me send out that version to clarify what I mean.
>>>
>>
>> Hi Thierry:
>>
>> The patch ("PCI: fix oops when try to find Root Port for a PCI device")
>> has been merge to the linus mainline tree before you found this 
>> deficiencies
> 
> I understand that. I'm just saying that there's no point keeping that
> change around because it no longer makes sense after we initialize the
> highest_pcie_bridge variable to dev.
> 

Ok, NO problem.:)

> Thierry
> 

Re: [PATCH net] PCI: fix the return value for the pci_find_pcie_root_port()

[Thierry Reding]

On Thu, Aug 17, 2017 at 08:40:16PM +0800, Ding Tianhong wrote:
> 
> 
> On 2017/8/17 18:51, Thierry Reding wrote:
> > On Thu, Aug 17, 2017 at 10:25:30AM +0800, Ding Tianhong wrote:
> >> The pci_find_pcie_root_port() would return NULL if the given
> >> dev is already a Root Port, it looks like unfriendly to the
> >> PCIe Root Port device, Thierry and Bjorn suggest to let this
> >> function return the given dev under this circumstances.
> >>
> >> Fixes: 0e405232871d6 ("PCI: fix oops when try to find Root Port for a PCI 
> >> device")
> >> Suggested-by: Thierry Reding 
> >> Suggested-by: Bjorn Helgaas 
> >> Signed-off-by: Thierry Reding 
> >> Signed-off-by: Ding Tianhong 
> >> ---
> >>  drivers/pci/pci.c | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> >> index 7e2022f..352bb53 100644
> >> --- a/drivers/pci/pci.c
> >> +++ b/drivers/pci/pci.c
> >> @@ -514,7 +514,7 @@ struct resource *pci_find_resource(struct pci_dev 
> >> *dev, struct resource *res)
> >>   */
> >>  struct pci_dev *pci_find_pcie_root_port(struct pci_dev *dev)
> >>  {
> >> -  struct pci_dev *bridge, *highest_pcie_bridge = NULL;
> >> +  struct pci_dev *bridge, *highest_pcie_bridge = dev;
> >>  
> >>bridge = pci_upstream_bridge(dev);
> >>while (bridge && pci_is_pcie(bridge)) {
> > 
> > I think this should actually be this change on top of a revert of commit
> > 0e405232871d6 ("PCI: fix oops when try to find Root Port for a PCI
> > device"). After the above change, the previous fix will have a redundant
> > check because highest_pcie_bridge will never be NULL.
> > 
> > Let me send out that version to clarify what I mean.
> > 
> 
> Hi Thierry:
> 
> The patch ("PCI: fix oops when try to find Root Port for a PCI device")
> has been merge to the linus mainline tree before you found this 
> deficiencies

I understand that. I'm just saying that there's no point keeping that
change around because it no longer makes sense after we initialize the
highest_pcie_bridge variable to dev.

Thierry


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Re: [PATCH net] PCI: fix the return value for the pci_find_pcie_root_port()

[Ding Tianhong]

On 2017/8/17 18:51, Thierry Reding wrote:
> On Thu, Aug 17, 2017 at 10:25:30AM +0800, Ding Tianhong wrote:
>> The pci_find_pcie_root_port() would return NULL if the given
>> dev is already a Root Port, it looks like unfriendly to the
>> PCIe Root Port device, Thierry and Bjorn suggest to let this
>> function return the given dev under this circumstances.
>>
>> Fixes: 0e405232871d6 ("PCI: fix oops when try to find Root Port for a PCI 
>> device")
>> Suggested-by: Thierry Reding 
>> Suggested-by: Bjorn Helgaas 
>> Signed-off-by: Thierry Reding 
>> Signed-off-by: Ding Tianhong 
>> ---
>>  drivers/pci/pci.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
>> index 7e2022f..352bb53 100644
>> --- a/drivers/pci/pci.c
>> +++ b/drivers/pci/pci.c
>> @@ -514,7 +514,7 @@ struct resource *pci_find_resource(struct pci_dev *dev, 
>> struct resource *res)
>>   */
>>  struct pci_dev *pci_find_pcie_root_port(struct pci_dev *dev)
>>  {
>> -struct pci_dev *bridge, *highest_pcie_bridge = NULL;
>> +struct pci_dev *bridge, *highest_pcie_bridge = dev;
>>  
>>  bridge = pci_upstream_bridge(dev);
>>  while (bridge && pci_is_pcie(bridge)) {
> 
> I think this should actually be this change on top of a revert of commit
> 0e405232871d6 ("PCI: fix oops when try to find Root Port for a PCI
> device"). After the above change, the previous fix will have a redundant
> check because highest_pcie_bridge will never be NULL.
> 
> Let me send out that version to clarify what I mean.
> 

Hi Thierry:

The patch ("PCI: fix oops when try to find Root Port for a PCI device")
has been merge to the linus mainline tree before you found this deficiencies

Regards
Tianhong

> Thierry
> 

Re: [PATCH net] PCI: fix the return value for the pci_find_pcie_root_port()

[Thierry Reding]

On Thu, Aug 17, 2017 at 10:25:30AM +0800, Ding Tianhong wrote:
> The pci_find_pcie_root_port() would return NULL if the given
> dev is already a Root Port, it looks like unfriendly to the
> PCIe Root Port device, Thierry and Bjorn suggest to let this
> function return the given dev under this circumstances.
> 
> Fixes: 0e405232871d6 ("PCI: fix oops when try to find Root Port for a PCI 
> device")
> Suggested-by: Thierry Reding 
> Suggested-by: Bjorn Helgaas 
> Signed-off-by: Thierry Reding 
> Signed-off-by: Ding Tianhong 
> ---
>  drivers/pci/pci.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 7e2022f..352bb53 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -514,7 +514,7 @@ struct resource *pci_find_resource(struct pci_dev *dev, 
> struct resource *res)
>   */
>  struct pci_dev *pci_find_pcie_root_port(struct pci_dev *dev)
>  {
> - struct pci_dev *bridge, *highest_pcie_bridge = NULL;
> + struct pci_dev *bridge, *highest_pcie_bridge = dev;
>  
>   bridge = pci_upstream_bridge(dev);
>   while (bridge && pci_is_pcie(bridge)) {

I think this should actually be this change on top of a revert of commit
0e405232871d6 ("PCI: fix oops when try to find Root Port for a PCI
device"). After the above change, the previous fix will have a redundant
check because highest_pcie_bridge will never be NULL.

Let me send out that version to clarify what I mean.

Thierry


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Re: [PATCH net] PCI: fix the return value for the pci_find_pcie_root_port()

[David Miller]

From: Ding Tianhong 
Date: Thu, 17 Aug 2017 10:25:30 +0800

> The pci_find_pcie_root_port() would return NULL if the given
> dev is already a Root Port, it looks like unfriendly to the
> PCIe Root Port device, Thierry and Bjorn suggest to let this
> function return the given dev under this circumstances.
> 
> Fixes: 0e405232871d6 ("PCI: fix oops when try to find Root Port for a PCI 
> device")
> Suggested-by: Thierry Reding 
> Suggested-by: Bjorn Helgaas 
> Signed-off-by: Thierry Reding 
> Signed-off-by: Ding Tianhong 

Bjorn, please review and ACK so Linus doesn't rip my head off again
:-)

Thanks.