From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id ACBB240DFDB for ; Thu, 30 Apr 2026 00:35:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777509345; cv=none; b=Xs3pTLdWioGssgFMqhQyFJ6g+O6PbJx+42Fvn4BpmsdyrGJaFOFg6oB7jEfeMZcyD1Wje2wjnpFLHLpljLtgZjlJVyhvVld39fu9dFZv0lJFS/4kq+A9V9VeSmP4o6Mb8tAsfgXybrFmWwF5BAu5anqnrQNaA1ovR9rmEyAXCbo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777509345; c=relaxed/simple; bh=tHRXmR6VQcmnd19CwjoHzYakRyuHtTseVwT528iMuKU=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=j4o0MIe8ta8R1O18AxkDwn2A1gpJ5o1G6/atbI98kEsm2tEbwkcMqe48li43aM3Ozsb4q2HLxmrk9obeqfMJNHWD/U1B8mpFqJkLSHK79RATjkPQP/tY5qAFQ2oli0DimTxW4dMyvd4qsjrhGHYdRQLWJDWqAuOvZZ8OaRlhQlw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DPy0PUVJ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="DPy0PUVJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0A63CC19425; Thu, 30 Apr 2026 00:35:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777509345; bh=tHRXmR6VQcmnd19CwjoHzYakRyuHtTseVwT528iMuKU=; h=From:To:Cc:Subject:Date:From; b=DPy0PUVJW83UpfZBqsi9lPec3HuIW0irun3ai/DHBzijhJESyj4qF+RXyeNgIBOAA EFja8nDGuyRbaZhUXqE1id/anUIloU4f7hRqmjIBsotYl05NwkFbMEI4MwVNt+Qxoo CfWmZI+meDAB/SjVHKHiur9bxDKALzXzK7abQz/y7L19RzH7Mzm+Nh4rHNRWm9poV8 nc3aWfvDTgkeI3fohtYVcBztol4mbfcaY84nPW2p9SVh+NMaI6f1GREfoWc7nw1sGZ DOAH11qdGwLA7E2i5QP0IKlSnekSO7xqmLCKbduwN3xTJO5vC0793/JViF+txU3xAK 7hCsmL3I37Qsw== From: =?UTF-8?q?Krzysztof=20Wilczy=C5=84ski?= To: Bjorn Helgaas Cc: Bjorn Helgaas , Manivannan Sadhasivam , Lorenzo Pieralisi , =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= , Lukas Wunner , Shuan He , linux-pci@vger.kernel.org Subject: [PATCH] PCI/proc: Fix race between pci_proc_init() and 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 pci_proc_attach_device() creates procfs entries for PCI devices and is called from pci_bus_add_device(). It returns early if proc_initialized is not yet set. On x86 with ACPI, PCI enumeration occurs at subsys_initcall, before pci_proc_init() sets proc_initialized at device_initcall. The for_each_pci_dev() loop in pci_proc_init() creates procfs entries for these already-enumerated devices. This loop runs without holding any lock. On ARM64 with devicetree, PCI host bridges probe at device_initcall. With async probing enabled, pci_bus_add_device() can run concurrently with pci_proc_init(), and both may call pci_proc_attach_device() for the same device, leading to duplicate proc_create_data() calls. Thus, wrap the for_each_pci_dev() loop with pci_lock_rescan_remove() to serialise against concurrent PCI bus operations. Add an early return in pci_proc_attach_device() when dev->procent is already set, making the function idempotent and symmetric with pci_proc_detach_device() which clears this field. While at it, update code to match preferred style and help with readability. Signed-off-by: Krzysztof Wilczyński --- drivers/pci/proc.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c index ce36e35681e8..9326f235bc58 100644 --- a/drivers/pci/proc.c +++ b/drivers/pci/proc.c @@ -425,6 +425,9 @@ int pci_proc_attach_device(struct pci_dev *dev) if (!proc_initialized) return -EACCES; + if (dev->procent) + return 0; + if (!bus->procdir) { if (pci_proc_domain(bus)) { sprintf(name, "%04x:%02x", pci_domain_nr(bus), @@ -464,12 +467,17 @@ int pci_proc_detach_bus(struct pci_bus *bus) static int __init pci_proc_init(void) { struct pci_dev *dev = NULL; + proc_bus_pci_dir = proc_mkdir("bus/pci", NULL); proc_create_seq("devices", 0, proc_bus_pci_dir, - &proc_bus_pci_devices_op); + &proc_bus_pci_devices_op); + proc_initialized = 1; + + pci_lock_rescan_remove(); for_each_pci_dev(dev) pci_proc_attach_device(dev); + pci_unlock_rescan_remove(); return 0; } -- 2.54.0