From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ding Tianhong Subject: Re: [PATCH net] PCI: fix the return value for the pci_find_pcie_root_port() Date: Thu, 17 Aug 2017 21:38:02 +0800 Message-ID: <7b19e5fe-e6b8-e51d-53a3-0f9ee328a842@huawei.com> References: <1502936730-7368-1-git-send-email-dingtianhong@huawei.com> <20170817105156.GA18789@ulmo> <20170817133012.GC6854@ulmo> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: mark.rutland@arm.com, gabriele.paoloni@huawei.com, asit.k.mallick@intel.com, catalin.marinas@arm.com, will.deacon@arm.com, linuxarm@huawei.com, alexander.duyck@gmail.com, ashok.raj@intel.com, eric.dumazet@gmail.com, helgaas@kernel.org, jeffrey.t.kirsher@intel.com, linux-pci@vger.kernel.org, ganeshgr@chelsio.com, Bob.Shaw@amd.com, leedom@chelsio.com, patrick.j.cramer@intel.com, bhelgaas@google.com, werner@chelsio.com, linux-arm-kernel@lists.infradead.org, amira@mellanox.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, David.Laight@aculab.com, Suravee.Suthikulpanit@amd.com, robin.murphy@arm.com, davem@davemloft.net, l.stach@pengutronix.de To: Thierry Reding Return-path: In-Reply-To: <20170817133012.GC6854@ulmo> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org List-Id: netdev.vger.kernel.org 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 >