{"id":2230765,"url":"http://patchwork.ozlabs.org/api/patches/2230765/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-pci/patch/20260430003542.455198-1-kwilczynski@kernel.org/","project":{"id":28,"url":"http://patchwork.ozlabs.org/api/projects/28/?format=json","name":"Linux PCI development","link_name":"linux-pci","list_id":"linux-pci.vger.kernel.org","list_email":"linux-pci@vger.kernel.org","web_url":null,"scm_url":null,"webscm_url":null,"list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20260430003542.455198-1-kwilczynski@kernel.org>","list_archive_url":null,"date":"2026-04-30T00:35:42","name":"PCI/proc: Fix race between pci_proc_init() and pci_bus_add_device()","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"94ffe2c2ace04f6f787ce7cc2808fe4cff42827b","submitter":{"id":86709,"url":"http://patchwork.ozlabs.org/api/people/86709/?format=json","name":"Krzysztof Wilczyński","email":"kwilczynski@kernel.org"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/linux-pci/patch/20260430003542.455198-1-kwilczynski@kernel.org/mbox/","series":[{"id":502177,"url":"http://patchwork.ozlabs.org/api/series/502177/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-pci/list/?series=502177","date":"2026-04-30T00:35:42","name":"PCI/proc: Fix race between pci_proc_init() and pci_bus_add_device()","version":1,"mbox":"http://patchwork.ozlabs.org/series/502177/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2230765/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2230765/checks/","tags":{},"related":[],"headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-pci@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256\n header.s=k20201202 header.b=DPy0PUVJ;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c0a:e001:db::12fc:5321; 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a=rsa-sha256; c=relaxed/simple; d=kernel.org;\n\ts=k20201202; t=1777509345;\n\tbh=tHRXmR6VQcmnd19CwjoHzYakRyuHtTseVwT528iMuKU=;\n\th=From:To:Cc:Subject:Date:From;\n\tb=DPy0PUVJW83UpfZBqsi9lPec3HuIW0irun3ai/DHBzijhJESyj4qF+RXyeNgIBOAA\n\t EFja8nDGuyRbaZhUXqE1id/anUIloU4f7hRqmjIBsotYl05NwkFbMEI4MwVNt+Qxoo\n\t CfWmZI+meDAB/SjVHKHiur9bxDKALzXzK7abQz/y7L19RzH7Mzm+Nh4rHNRWm9poV8\n\t nc3aWfvDTgkeI3fohtYVcBztol4mbfcaY84nPW2p9SVh+NMaI6f1GREfoWc7nw1sGZ\n\t DOAH11qdGwLA7E2i5QP0IKlSnekSO7xqmLCKbduwN3xTJO5vC0793/JViF+txU3xAK\n\t 7hCsmL3I37Qsw==","From":"=?utf-8?q?Krzysztof_Wilczy=C5=84ski?= ","To":"Bjorn Helgaas ","Cc":"Bjorn Helgaas ,\n Manivannan Sadhasivam ,\n Lorenzo Pieralisi ,\n =?utf-8?q?Ilpo_J=C3=A4rvinen?= ,\n Lukas Wunner , Shuan He ,\n linux-pci@vger.kernel.org","Subject":"[PATCH] PCI/proc: Fix race between pci_proc_init() and\n pci_bus_add_device()","Date":"Thu, 30 Apr 2026 00:35:42 +0000","Message-ID":"<20260430003542.455198-1-kwilczynski@kernel.org>","X-Mailer":"git-send-email 2.54.0","Precedence":"bulk","X-Mailing-List":"linux-pci@vger.kernel.org","List-Id":"","List-Subscribe":"","List-Unsubscribe":"","MIME-Version":"1.0","Content-Type":"text/plain; charset=UTF-8","Content-Transfer-Encoding":"8bit"},"content":"pci_proc_attach_device() creates procfs entries for PCI devices and is\ncalled from pci_bus_add_device(). It returns early if proc_initialized\nis not yet set.\n\nOn x86 with ACPI, PCI enumeration occurs at subsys_initcall, before\npci_proc_init() sets proc_initialized at device_initcall. The\nfor_each_pci_dev() loop in pci_proc_init() creates procfs entries for\nthese already-enumerated devices. This loop runs without holding any\nlock.\n\nOn ARM64 with devicetree, PCI host bridges probe at device_initcall.\nWith async probing enabled, pci_bus_add_device() can run concurrently\nwith pci_proc_init(), and both may call pci_proc_attach_device() for\nthe same device, leading to duplicate proc_create_data() calls.\n\nThus, wrap the for_each_pci_dev() loop with pci_lock_rescan_remove() to\nserialise against concurrent PCI bus operations. Add an early return in\npci_proc_attach_device() when dev->procent is already set, making the\nfunction idempotent and symmetric with pci_proc_detach_device() which\nclears this field.\n\nWhile at it, update code to match preferred style and help with\nreadability.\n\nSigned-off-by: Krzysztof Wilczyński \n---\n drivers/pci/proc.c | 10 +++++++++-\n 1 file changed, 9 insertions(+), 1 deletion(-)","diff":"diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c\nindex ce36e35681e8..9326f235bc58 100644\n--- a/drivers/pci/proc.c\n+++ b/drivers/pci/proc.c\n@@ -425,6 +425,9 @@ int pci_proc_attach_device(struct pci_dev *dev)\n \tif (!proc_initialized)\n \t\treturn -EACCES;\n \n+\tif (dev->procent)\n+\t\treturn 0;\n+\n \tif (!bus->procdir) {\n \t\tif (pci_proc_domain(bus)) {\n \t\t\tsprintf(name, \"%04x:%02x\", pci_domain_nr(bus),\n@@ -464,12 +467,17 @@ int pci_proc_detach_bus(struct pci_bus *bus)\n static int __init pci_proc_init(void)\n {\n \tstruct pci_dev *dev = NULL;\n+\n \tproc_bus_pci_dir = proc_mkdir(\"bus/pci\", NULL);\n \tproc_create_seq(\"devices\", 0, proc_bus_pci_dir,\n-\t\t &proc_bus_pci_devices_op);\n+\t\t\t&proc_bus_pci_devices_op);\n+\n \tproc_initialized = 1;\n+\n+\tpci_lock_rescan_remove();\n \tfor_each_pci_dev(dev)\n \t\tpci_proc_attach_device(dev);\n+\tpci_unlock_rescan_remove();\n \n \treturn 0;\n }\n","prefixes":[]}