From patchwork Thu Aug 6 04:14:55 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Tomlinson X-Patchwork-Id: 1341471 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=linux-pci-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=alliedtelesis.co.nz Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=alliedtelesis.co.nz header.i=@alliedtelesis.co.nz header.a=rsa-sha256 header.s=mail181024 header.b=Si2lRLsH; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4BMZsD1Kttz9sR4 for ; Thu, 6 Aug 2020 14:15:12 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726388AbgHFEPL (ORCPT ); Thu, 6 Aug 2020 00:15:11 -0400 Received: from gate2.alliedtelesis.co.nz ([202.36.163.20]:37543 "EHLO gate2.alliedtelesis.co.nz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726159AbgHFEPK (ORCPT ); Thu, 6 Aug 2020 00:15:10 -0400 Received: from mmarshal3.atlnz.lc (mmarshal3.atlnz.lc [10.32.18.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by gate2.alliedtelesis.co.nz (Postfix) with ESMTPS id 1F1968011F; Thu, 6 Aug 2020 16:15:06 +1200 (NZST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alliedtelesis.co.nz; s=mail181024; t=1596687306; bh=y/TS5dY/e8pkHaHRXcCzB2vajvea5CBxtY3MHgzDUiw=; h=From:To:Cc:Subject:Date; b=Si2lRLsHzS9JXlt0wpsVDwE4y5ZY79wRzK0RtbWTtiIbLSzcsDamNJlBiLDap3SGy EXI5ZMv6egTG38LtOrV8PKLi/2Rro8+g84jMQ2A5erGNm0aUiEENYCyXbVrWoW4edt 0ebmxxROMi+hkIrMqgYQxfO1mgBG1DEP72HAHsw8mm8Qxnvon5EhzWfFq2396w/Pb4 oBRBmff6pdQfFea8rWtJqPzl6jMgDXh/lmLhyMKYjPJsqwiVFxGK7VokDxovweFpx+ mcFN2mIbAXW5R2lWKYB1hv6Fqg4t3fS1U3Q5KIaLVLMFT8wgDM2CMTa7kKpLr282za kDepSIhcOb6XQ== Received: from smtp (Not Verified[10.32.16.33]) by mmarshal3.atlnz.lc with Trustwave SEG (v7,5,8,10121) id ; Thu, 06 Aug 2020 16:15:06 +1200 Received: from markto-dl.ws.atlnz.lc (markto-dl.ws.atlnz.lc [10.33.23.25]) by smtp (Postfix) with ESMTP id AB2EB13EEBA; Thu, 6 Aug 2020 16:15:04 +1200 (NZST) Received: by markto-dl.ws.atlnz.lc (Postfix, from userid 1155) id CFB3E341096; Thu, 6 Aug 2020 16:15:05 +1200 (NZST) From: Mark Tomlinson To: ray.jui@broadcom.com, helgaas@kernel.org, sbranden@broadcom.com, f.fainelli@gmail.com, lorenzo.pieralisi@arm.com, robh@kernel.org Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Mark Tomlinson Subject: [PATCH v4] PCI: Reduce warnings on possible RW1C corruption Date: Thu, 6 Aug 2020 16:14:55 +1200 Message-Id: <20200806041455.11070-1-mark.tomlinson@alliedtelesis.co.nz> X-Mailer: git-send-email 2.28.0 MIME-Version: 1.0 x-atlnz-ls: pat Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org For hardware that only supports 32-bit writes to PCI there is the possibility of clearing RW1C (write-one-to-clear) bits. A rate-limited messages was introduced by fb2659230120, but rate-limiting is not the best choice here. Some devices may not show the warnings they should if another device has just produced a bunch of warnings. Also, the number of messages can be a nuisance on devices which are otherwise working fine. This patch changes the ratelimit to a single warning per bus. This ensures no bus is 'starved' of emitting a warning and also that there isn't a continuous stream of warnings. It would be preferable to have a warning per device, but the pci_dev structure is not available here, and a lookup from devfn would be far too slow. Suggested-by: Bjorn Helgaas Fixes: fb2659230120 ("PCI: Warn on possible RW1C corruption for sub-32 bit config writes") Signed-off-by: Mark Tomlinson Acked-by: Scott Branden Reviewed-by: Florian Fainelli Reviewed-by: Rob Herring --- changes in v4: - Use bitfield rather than bool to save memory (was meant to be in v3). drivers/pci/access.c | 9 ++++++--- include/linux/pci.h | 1 + 2 files changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/pci/access.c b/drivers/pci/access.c index 79c4a2ef269a..b452467fd133 100644 --- a/drivers/pci/access.c +++ b/drivers/pci/access.c @@ -160,9 +160,12 @@ int pci_generic_config_write32(struct pci_bus *bus, unsigned int devfn, * write happen to have any RW1C (write-one-to-clear) bits set, we * just inadvertently cleared something we shouldn't have. */ - dev_warn_ratelimited(&bus->dev, "%d-byte config write to %04x:%02x:%02x.%d offset %#x may corrupt adjacent RW1C bits\n", - size, pci_domain_nr(bus), bus->number, - PCI_SLOT(devfn), PCI_FUNC(devfn), where); + if (!bus->unsafe_warn) { + dev_warn(&bus->dev, "%d-byte config write to %04x:%02x:%02x.%d offset %#x may corrupt adjacent RW1C bits\n", + size, pci_domain_nr(bus), bus->number, + PCI_SLOT(devfn), PCI_FUNC(devfn), where); + bus->unsafe_warn = 1; + } mask = ~(((1 << (size * 8)) - 1) << ((where & 0x3) * 8)); tmp = readl(addr) & mask; diff --git a/include/linux/pci.h b/include/linux/pci.h index 34c1c4f45288..85211a787f8b 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -626,6 +626,7 @@ struct pci_bus { struct bin_attribute *legacy_io; /* Legacy I/O for this bus */ struct bin_attribute *legacy_mem; /* Legacy mem */ unsigned int is_added:1; + unsigned int unsafe_warn:1; /* warned about RW1C config write */ }; #define to_pci_bus(n) container_of(n, struct pci_bus, dev)