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 9DD724921AA; Sat, 28 Feb 2026 17:43:50 +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=1772300630; cv=none; b=XYXUiSE9yiLS/mgkZDyAXp55+MZQGyIyloahEoqCXwX4CRmZG/8XzVsuyliJ0ZRlQHUO4EGqwePC8s17mcMhMwe1VnfhYvd3eREM0Ui1Hn+XFNRack2outEK69YPLmeLRGyfyTLL6qE8rH2M3F77Xl8uVlfK+xExq3rraBmbvjw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772300630; c=relaxed/simple; bh=6cfPf4UrLZqeLG2ynVj+rtBkw4gw8pRAYGT4JMrGWWg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kl26mdNjm6H9QzAkUVWIjvqNTzgpwtYP0uuLoKw7wO0HQaujlc0utsiK1oDF5DwgsMyXlHBaeWFjfPYV3Z59l8r9F7bo/tV/t/l7ONDtrk9L40S0TlbRmNUwzSW7GG1PLKCP1/i8dKEGz/yGBD8lzOclmHxLLIIE5o8iL/FwsPA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=klf3YEPa; 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="klf3YEPa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C9D3BC116D0; Sat, 28 Feb 2026 17:43:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772300630; bh=6cfPf4UrLZqeLG2ynVj+rtBkw4gw8pRAYGT4JMrGWWg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=klf3YEPaZDHBlAdwif+Ih/nWSAwnzOHiOy5/J95EylJcj0skfC7Pnyee4pvvna27M Rgs3aSAqbrvg6uu7n6xJtqdx7MYYJ/os0k0lAt8uDT7Gi1K2KxJIeMuoUh2/daqrDh OPmq7YE5nZt+gRfp+cb9orQfcZBHpvTm4rYvlLEcDSbOscMpt5+OHslXHVoeeCNXrZ ojxpL6tEgP1F3w55odJQbBADiSsOZQqFnt/S7MPI5rqAtyMoFvKmp6fywekQ2xmOf6 h77C8masdAYmwtO+voKZ3oshDqzKylIDLIZ8nowH3DxaurveUzoi0QZNq5heypA2xj ElUfbKZ9YUlnQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Brian Norris , Bjorn Helgaas , Marek Szyprowski , Sasha Levin Subject: [PATCH 6.19 671/844] PCI/PM: Prevent runtime suspend until devices are fully initialized Date: Sat, 28 Feb 2026 12:29:44 -0500 Message-ID: <20260228173244.1509663-672-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260228173244.1509663-1-sashal@kernel.org> References: <20260228173244.1509663-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit From: Brian Norris [ Upstream commit 51c0996dadaea20d73eb0495aeda9cb0422243e8 ] Previously, it was possible for a PCI device to be runtime-suspended before it was fully initialized. When that happened, the suspend process could save invalid device state, for example, before BAR assignment. Restoring the invalid state during resume may leave the device non-functional. Prevent runtime suspend for PCI devices until they are fully initialized by deferring pm_runtime_enable(). More details on how exactly this may occur: 1. PCI device is created by pci_scan_slot() or similar 2. As part of pci_scan_slot(), pci_pm_init() puts the device in D0 and prevents runtime suspend prevented via pm_runtime_forbid() 3. pci_device_add() adds the underlying 'struct device' via device_add(), which means user space can allow runtime suspend, e.g., echo auto > /sys/bus/pci/devices/.../power/control 4. PCI device receives BAR configuration (pci_assign_unassigned_bus_resources(), etc.) 5. pci_bus_add_device() applies final fixups, saves device state, and tries to attach a driver The device may potentially be suspended between #3 and #5, so this is racy with user space (udev or similar). Many PCI devices are enumerated at subsys_initcall time and so will not race with user space, but devices created later by hotplug or modular pwrctrl or host controller drivers are susceptible to this race. More runtime PM details at the first Link: below. Link: https://lore.kernel.org/all/0e35a4e1-894a-47c1-9528-fc5ffbafd9e2@samsung.com/ Signed-off-by: Brian Norris [bhelgaas: update comments per https://lore.kernel.org/r/CAJZ5v0iBNOmMtqfqEbrYyuK2u+2J2+zZ-iQd1FvyCPjdvU2TJg@mail.gmail.com] Signed-off-by: Bjorn Helgaas Tested-by: Marek Szyprowski Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260122094815.v5.1.I60a53c170a8596661883bd2b4ef475155c7aa72b@changeid Signed-off-by: Sasha Levin --- drivers/pci/bus.c | 8 ++++++++ drivers/pci/pci.c | 8 +++++++- 2 files changed, 15 insertions(+), 1 deletion(-) diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c index 4383a36fd6ca0..41e5c45e38b5e 100644 --- a/drivers/pci/bus.c +++ b/drivers/pci/bus.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include @@ -379,6 +380,13 @@ void pci_bus_add_device(struct pci_dev *dev) put_device(&pdev->dev); } + /* + * Enable runtime PM, which potentially allows the device to + * suspend immediately, only after the PCI state has been + * configured completely. + */ + pm_runtime_enable(&dev->dev); + if (!dn || of_device_is_available(dn)) pci_dev_allow_binding(dev); diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index f21f6933c9b63..a4eb3bc2127ae 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -3199,8 +3199,14 @@ void pci_pm_init(struct pci_dev *dev) poweron: pci_pm_power_up_and_verify_state(dev); pm_runtime_forbid(&dev->dev); + + /* + * Runtime PM will be enabled for the device when it has been fully + * configured, but since its parent and suppliers may suspend in + * the meantime, prevent them from doing so by changing the + * device's runtime PM status to "active". + */ pm_runtime_set_active(&dev->dev); - pm_runtime_enable(&dev->dev); } static unsigned long pci_ea_flags(struct pci_dev *dev, u8 prop) -- 2.51.0