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Fri, 04 Sep 2026 08:36:13 -0700 (PDT) Message-ID: <6f916404-63b5-40a3-a429-befe42a08629@arista.com> Date: Fri, 4 Sep 2026 16:36:12 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [PATCH] PCI: Stop waiting for link status after config read failure To: Lukas Wunner Cc: bhelgaas@google.com, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, James Sewart References: <20260904111318.1063858-1-yurypm@arista.com> Content-Language: en-US From: "Yury M." In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit what to you think about this check: if ((pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnksta) ||  PCI_POSSIBLE_ERROR(lnksta)) && pci_dev_is_disconnected(pdev))     return -ENODEV; On 9/4/26 13:20, Lukas Wunner wrote: > On Fri, Sep 04, 2026 at 11:13:18AM +0000, Yury Murashka wrote: >> With a nested PCIe topology with multiple layers of hotplug, a link can go >> down near the bottom of the topology shortly before a link above it goes >> down. In that case, pcie_wait_for_link_status() can wait for the full >> timeout while every read of the link status register fails because the >> device has disappeared. >> >> Return immediately when reading the link status fails so event processing >> can continue. > [...] >> +++ b/drivers/pci/pci.c >> @@ -4580,7 +4581,8 @@ static int pcie_wait_for_link_status(struct pci_dev *pdev, >> >> end_jiffies = jiffies + msecs_to_jiffies(PCIE_LINK_RETRAIN_TIMEOUT_MS); >> do { >> - pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnksta); >> + if (pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnksta)) >> + return -ENODEV; >> if ((lnksta & lnksta_mask) == lnksta_match) >> return 0; >> msleep(1); > It might be clearer if you check for pci_dev_is_disconnected() directly > instead of relying on a PCIBIOS_DEVICE_NOT_FOUND return value which is > generated as a side effect of the device being gone. > > Thanks, > > Lukas