From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B296FC433F5 for ; Fri, 4 Mar 2022 22:01:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229943AbiCDWCT (ORCPT ); Fri, 4 Mar 2022 17:02:19 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57786 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229535AbiCDWCS (ORCPT ); Fri, 4 Mar 2022 17:02:18 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 28BBA27C7A3; Fri, 4 Mar 2022 14:01:30 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 9BA1961E6A; Fri, 4 Mar 2022 22:01:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CF5CFC340E9; Fri, 4 Mar 2022 22:01:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646431289; bh=NPSR2P2E9oglZhlRfhiq9YTm0uMP5sV5KksP4bLLrfs=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=HIxZcn7WPBbkoeTEu+C1p6Ky46Ni1FwuHZBIXFab56JpNahvB1RMS5lcMipCcWK66 VPux6dE0ZQJpzxWNytW1wNestxWXPgBTkuonq5AtTdM52Tt04xMulaxlW9BiDbw25a EE1bNV6InHH+NqAoCmWJ7hcbjCs7IQpWvrRX2IrXf3+JmrSfR8BlX1KW/R2w/PONbN GFYRwreK2G7oNrMhfRkXtlFEgGAYC5QWxO99TJKAbiWQEXUNV4S6t1rcpmfmZqAuJ9 2ZpTpSFPPnwhgP1sHp4m7hKB5/rZelRP20kdkxmn+8cXZFDigC+MslYt31qRmvqcfl MROt6CD2RNrmQ== Date: Fri, 4 Mar 2022 16:01:27 -0600 From: Bjorn Helgaas To: Chris Packham Cc: Mark Tomlinson , "ray.jui@broadcom.com" , "sbranden@broadcom.com" , "f.fainelli@gmail.com" , "lorenzo.pieralisi@arm.com" , "robh@kernel.org" , "linux-pci@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v4] PCI: Reduce warnings on possible RW1C corruption Message-ID: <20220304220127.GA1058143@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <679ac5f4-d6b7-5c94-39d5-441c68576911@alliedtelesis.co.nz> Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Fri, Mar 04, 2022 at 01:30:29AM +0000, Chris Packham wrote: > Hi All, > > On 21/08/20 10:11, Bjorn Helgaas wrote: > > On Thu, Aug 06, 2020 at 04:14:55PM +1200, Mark Tomlinson wrote: > >> 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 > > Applied with collected reviews/acks to pci/enumeration for v5.10, > > thanks! > > Whatever happened to this change? > > I'm just going through our queue of patches that have been sent upstream > and expected this one to be gone after we pulled v5.10. Looking at > Linus's tree I don't see it ever having been applied. I couldn't see > anything on the relevant mailing lists suggesting that there was a > problem with this change so I'm just wondering what's happened to it? Sorry, I blew it somehow and dropped it. I applied it again for v5.18. Thanks for noticing! > >> --- > >> 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) > >> -- > >> 2.28.0 > >>