From patchwork Fri Jul 31 03:39:56 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Tomlinson X-Patchwork-Id: 11693957 X-Patchwork-Delegate: bhelgaas@google.com Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A04D91744 for ; Fri, 31 Jul 2020 03:40:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 87E4F206D8 for ; Fri, 31 Jul 2020 03:40:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=alliedtelesis.co.nz header.i=@alliedtelesis.co.nz header.b="sJieyIcu" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731357AbgGaDkT (ORCPT ); Thu, 30 Jul 2020 23:40:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35780 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731356AbgGaDkT (ORCPT ); Thu, 30 Jul 2020 23:40:19 -0400 Received: from gate2.alliedtelesis.co.nz (gate2.alliedtelesis.co.nz [IPv6:2001:df5:b000:5::4]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9E9FEC061575 for ; Thu, 30 Jul 2020 20:40:16 -0700 (PDT) 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 24583891B0; Fri, 31 Jul 2020 15:40:10 +1200 (NZST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alliedtelesis.co.nz; s=mail181024; t=1596166810; bh=QyXhMPzrP1ywAXT26zbyvUCAWusApigo/oSgJG0v9js=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=sJieyIcuSWEYih5V68ENnpm4Chl+d0iygWUWLe+S5LlAg6iKxRrA7r81ZKASRWDrM P8whcraJ/uuN/G0hamgmHhHI4wY4eImTxvSu5Fd3aVf9V2jz1msOl3Rr2xgBjkHOWN 7sSLMis8pbZydqFtM5F1QagwPrb1C67paRq73roApiRgdVPDvOQQBbjORbHjPA1PLC Aoo2WOM3PDdRSPlJrD/8BDnE10p+CsH04/4AoQf08CzWZbxryho1SaCaivaaWO68Tp l6VBvaz0uQws+MGySqSAJAcf4p1KvV7v0+cO7c60cf6OVqqzVE99cu3o6dW3RlK4SV a+KTZO70DJUcg== Received: from smtp (Not Verified[10.32.16.33]) by mmarshal3.atlnz.lc with Trustwave SEG (v7,5,8,10121) id ; Fri, 31 Jul 2020 15:40:10 +1200 Received: from markto-dl.ws.atlnz.lc (markto-dl.ws.atlnz.lc [10.33.23.25]) by smtp (Postfix) with ESMTP id 3386013EEFA; Fri, 31 Jul 2020 15:40:09 +1200 (NZST) Received: by markto-dl.ws.atlnz.lc (Postfix, from userid 1155) id DB97433ECD0; Fri, 31 Jul 2020 15:40:09 +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 v2 2/2] PCI: Reduce warnings on possible RW1C corruption Date: Fri, 31 Jul 2020 15:39:56 +1200 Message-Id: <20200731033956.6058-2-mark.tomlinson@alliedtelesis.co.nz> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200731033956.6058-1-mark.tomlinson@alliedtelesis.co.nz> References: <20200731033956.6058-1-mark.tomlinson@alliedtelesis.co.nz> 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 --- 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..ab85cb7df9b6 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 = true; + } 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..5b6ab593ae09 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -613,6 +613,7 @@ struct pci_bus { unsigned char primary; /* Number of primary bridge */ unsigned char max_bus_speed; /* enum pci_bus_speed */ unsigned char cur_bus_speed; /* enum pci_bus_speed */ + bool unsafe_warn; /* warned about RW1C config write */ #ifdef CONFIG_PCI_DOMAINS_GENERIC int domain_nr; #endif