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Thu, 20 Apr 2023 02:41:25 +0000 From: Dexuan Cui To: bhelgaas@google.com, davem@davemloft.net, decui@microsoft.com, edumazet@google.com, haiyangz@microsoft.com, jakeo@microsoft.com, kuba@kernel.org, kw@linux.com, kys@microsoft.com, leon@kernel.org, linux-pci@vger.kernel.org, lpieralisi@kernel.org, mikelley@microsoft.com, pabeni@redhat.com, robh@kernel.org, saeedm@nvidia.com, wei.liu@kernel.org, longli@microsoft.com, boqun.feng@gmail.com, ssengar@microsoft.com, helgaas@kernel.org Cc: linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org, netdev@vger.kernel.org, josete@microsoft.com, stable@vger.kernel.org Subject: [PATCH v3 6/6] PCI: hv: Use async probing to reduce boot time Date: Wed, 19 Apr 2023 19:40:37 -0700 Message-Id: <20230420024037.5921-7-decui@microsoft.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20230420024037.5921-1-decui@microsoft.com> References: <20230420024037.5921-1-decui@microsoft.com> X-ClientProxiedBy: MW4P221CA0023.NAMP221.PROD.OUTLOOK.COM (2603:10b6:303:8b::28) To BL0PR2101MB1092.namprd21.prod.outlook.com (2603:10b6:207:30::23) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL0PR2101MB1092:EE_|SJ1PR21MB3411:EE_ X-MS-Office365-Filtering-Correlation-Id: e38939b3-9173-4145-55d0-08db4148bbd2 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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Now with hbus->state_lock and other fixes, the race is resolved, so remove pci_{lock,unlock}_rescan_remove() in create_root_hv_pci_bus(): this removes the serialization in hv_pci_probe() and hence allows async-probing (PROBE_PREFER_ASYNCHRONOUS) to work. Add the async-probing flag to hv_pci_drv. pci_{lock,unlock}_rescan_remove() in hv_eject_device_work() and in hv_pci_remove() are still kept: according to the comment before drivers/pci/probe.c: static DEFINE_MUTEX(pci_rescan_remove_lock), "PCI device removal routines should always be executed under this mutex". Signed-off-by: Dexuan Cui Reviewed-by: Michael Kelley Reviewed-by: Long Li Cc: stable@vger.kernel.org --- v2: No change to the patch body. Improved the commit message [Michael Kelley] Added Cc:stable v3: Added Michael's and Long Li's Reviewed-by. Fixed a typo in the commit message: grubing -> grabing [Thanks, Michael!] drivers/pci/controller/pci-hyperv.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c index 3ae2f99dea8c2..2ea2b1b8a4c9a 100644 --- a/drivers/pci/controller/pci-hyperv.c +++ b/drivers/pci/controller/pci-hyperv.c @@ -2312,12 +2312,16 @@ static int create_root_hv_pci_bus(struct hv_pcibus_device *hbus) if (error) return error; - pci_lock_rescan_remove(); + /* + * pci_lock_rescan_remove() and pci_unlock_rescan_remove() are + * unnecessary here, because we hold the hbus->state_lock, meaning + * hv_eject_device_work() and pci_devices_present_work() can't race + * with create_root_hv_pci_bus(). + */ hv_pci_assign_numa_node(hbus); pci_bus_assign_resources(bridge->bus); hv_pci_assign_slots(hbus); pci_bus_add_devices(bridge->bus); - pci_unlock_rescan_remove(); hbus->state = hv_pcibus_installed; return 0; } @@ -4003,6 +4007,9 @@ static struct hv_driver hv_pci_drv = { .remove = hv_pci_remove, .suspend = hv_pci_suspend, .resume = hv_pci_resume, + .driver = { + .probe_type = PROBE_PREFER_ASYNCHRONOUS, + }, }; static void __exit exit_hv_pci_drv(void)