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 X-Spam-Level: X-Spam-Status: No, score=-14.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 487FBC433E2 for ; Thu, 10 Sep 2020 18:53:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 00916214F1 for ; Thu, 10 Sep 2020 18:53:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="JPZzWyhS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726710AbgIJSxm (ORCPT ); Thu, 10 Sep 2020 14:53:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40526 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726480AbgIJSuL (ORCPT ); Thu, 10 Sep 2020 14:50:11 -0400 Received: from mail-pf1-x443.google.com (mail-pf1-x443.google.com [IPv6:2607:f8b0:4864:20::443]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6F8B2C061573; Thu, 10 Sep 2020 11:50:10 -0700 (PDT) Received: by mail-pf1-x443.google.com with SMTP id c196so5322554pfc.0; Thu, 10 Sep 2020 11:50:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=aYjJfcYyIA8Xv1f/xwx7IbaGd+zm7NTIJSkG9721wPA=; b=JPZzWyhSb2c1eLwB3oxY/HV7INbOfJZ0uTRy5P1lBCRUyHB/Hfyybjo7hEZswy1iS0 awYvyjTox1dA6pYcpe8vznyhrPtDY9+XCgqRfLsyHnfOJXrBNQ1ie2pma/QZJGBnVKFg zVqBW3AbAjl4/9US0Hvfc1VON4eobYnBvxxx2sjafJinQvdVN2uqxBgwMcF523e/vAmH 86k16kpiiwYTK2DWMe/wKfznuz2KUiH9RV4JfvMxg8v5kjQaJ8cyrAredtW6dmqVcLRM tkHHCU660eBPvJ+KEDAjJUVx3tHLklBINRy7InXylmS6HwdGf15F3NfykCR9LcjIYinz JGwA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=aYjJfcYyIA8Xv1f/xwx7IbaGd+zm7NTIJSkG9721wPA=; b=O9FBfyAwgL+gj2XRk+liWiDNFZ1csGrFaBYGP7iQqdvd+7RqlUrK0kIvh2mmsk/gYU 3CqXQUXy17MjjWiRSM3GMQkX+JaXCgjH1AJEqYnG05xtqt86EJR8daL1VyXLN1p6qwqg 6k8ULGg6lbLFLcZCmwG+nzRSTm0L4DMiRW4Qd5AGDqBcVqm2UUGN7My/Mkp5zWI9WBAx wq3koY7rg/IzMyEcSyAsyBlBMP6ZTB1F7BJWU7Tr5ndH8Q5VetHbe+0rEvTHEuYxGHuZ Jv3PK2sHzaVrb7i6modVMwYsZjR6E/Xs+niLXmbbKlZzapLKwW1ciRrTDpFf/DTqQ2j0 YrXw== X-Gm-Message-State: AOAM533MgQtAWzIr19Ysq9NcCcVqn4+XmP9F1y7QhHi4i1mH+2lXs3xq SUVBrv/m/a3LEiUzzmK5CDfgk0zPHOo= X-Google-Smtp-Source: ABdhPJxeeYQs18O8YvaouZsBUCc33xkxtb909We38aM7ZCEaoYMy0JTvu+bVOUzUuGB6112/rN5Ktg== X-Received: by 2002:a63:471b:: with SMTP id u27mr5681257pga.139.1599763809889; Thu, 10 Sep 2020 11:50:09 -0700 (PDT) Received: from [10.230.30.107] ([192.19.223.252]) by smtp.gmail.com with ESMTPSA id i17sm6723289pfa.29.2020.09.10.11.50.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 10 Sep 2020 11:50:09 -0700 (PDT) Subject: Re: [PATCH] PCI: Don't use Printk in raw_spinlocks To: Bjorn Helgaas , Rob Herring Cc: Xingxing Su , Bjorn Helgaas , PCI , "linux-kernel@vger.kernel.org" , Mark Tomlinson , Scott Branden References: <20200910184627.GA804924@bjorn-Precision-5520> From: Florian Fainelli Message-ID: Date: Thu, 10 Sep 2020 11:50:07 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0 Thunderbird/78.2.1 MIME-Version: 1.0 In-Reply-To: <20200910184627.GA804924@bjorn-Precision-5520> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On 9/10/2020 11:46 AM, Bjorn Helgaas wrote: > On Thu, Sep 10, 2020 at 08:21:06AM -0600, Rob Herring wrote: >> On Wed, Sep 9, 2020 at 8:07 PM Bjorn Helgaas wrote: >>> >>> [+cc Mark, Florian, Rob, Scott] >>> >>> On Sat, Aug 01, 2020 at 09:25:49AM +0800, Xingxing Su wrote: >>>> Do not use printk in raw_spinlocks, >>>> it will cause BUG: Invalid wait context. >>>> >>>> The trace reported by lockdep follows. >>>> >>>> [ 2.986113] ============================= >>>> [ 2.986115] [ BUG: Invalid wait context ] >>>> [ 2.986116] 5.8.0-rc1+ #11 Not tainted >>>> [ 2.986118] ----------------------------- >>>> [ 2.986120] swapper/0/1 is trying to lock: >>>> [ 2.986122] ffffffff80f5ddd8 (console_owner){....}-{3:3}, at: console_unlock+0x284/0x820 >>>> [ 2.986130] other info that might help us debug this: >>>> [ 2.986132] context-{5:5} >>>> [ 2.986134] 3 locks held by swapper/0/1: >>>> [ 2.986135] #0: 98000007fa03c990 (&dev->mutex){....}-{0:0}, at: device_driver_attach+0x28/0x90 >>>> [ 2.986144] #1: ffffffff80fb83a8 (pci_lock){....}-{2:2}, at: pci_bus_write_config_word+0x60/0xb8 >>>> [ 2.986152] #2: ffffffff80f5ded0 (console_lock){+.+.}-{0:0}, at: vprintk_emit+0x1b0/0x3b8 >>>> [ 2.986161] stack backtrace: >>>> [ 2.986163] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.8.0-rc1+ #11 >>>> [ 2.986164] Stack : 0000000000001d67 98000000030be9b0 0000000000000001 7b2aba74f6c4785b >>>> [ 2.986172] 7b2aba74f6c4785b 0000000000000000 98000007f89cb438 ffffffff80e7dc80 >>>> [ 2.986181] 0000000000000001 000000000000000a 0000000000000001 0000000000000001 >>>> [ 2.986189] ffffffff80f4e156 fffffffffffffffd ffffffff80cc2d98 fffffffff8000000 >>>> [ 2.986197] 0000000024000000 ffffffff80f40000 0000000000000000 0000000000000000 >>>> [ 2.986205] ffffffff9500cce0 0000000000000000 ffffffff80f50000 ffffffff81546318 >>>> [ 2.986213] ffffffff81c4c3c0 0000000000000018 ffffffffbc000000 0000000000000000 >>>> [ 2.986221] ffffffff81340000 98000007f89c8000 98000007f89cb430 98000007f8a00000 >>>> [ 2.986229] ffffffff806be568 0000000000000000 0000000000000000 0000000000000000 >>>> [ 2.986237] 0000000000000000 0000000000000000 ffffffff80211c1c 7b2aba74f6c4785b >>>> [ 2.986245] ... >>>> [ 2.986250] Call Trace: >>>> [ 2.986251] [] show_stack+0x9c/0x130 >>>> [ 2.986253] [] dump_stack+0xe8/0x150 >>>> [ 2.986255] [] __lock_acquire+0x570/0x3250 >>>> [ 2.986257] [] lock_acquire+0x118/0x558 >>>> [ 2.986259] [] console_unlock+0x2e4/0x820 >>>> [ 2.986261] [] vprintk_emit+0x1c0/0x3b8 >>>> [ 2.986263] [] dev_vprintk_emit+0x1c8/0x210 >>>> [ 2.986265] [] dev_printk_emit+0x3c/0x60 >>>> [ 2.986267] [] _dev_warn+0x5c/0x80 >>>> [ 2.986269] [] pci_generic_config_write32+0x154/0x160 >>>> [ 2.986271] [] pci_bus_write_config_word+0x84/0xb8 >>>> [ 2.986273] [] pci_setup_device+0x22c/0x768 >>>> [ 2.986275] [] pci_scan_single_device+0xc8/0x100 >>>> [ 2.986277] [] pci_scan_slot+0xb0/0x178 >>>> [ 2.986279] [] pci_scan_child_bus_extend+0x5c/0x370 >>>> [ 2.986281] [] pci_scan_root_bus_bridge+0x6c/0xf0 >>>> [ 2.986283] [] pci_host_probe+0x1c/0xd8 >>>> [ 2.986285] [] platform_drv_probe+0x54/0xb8 >>>> [ 2.986287] [] really_probe+0x130/0x388 >>>> [ 2.986289] [] driver_probe_device+0x64/0xd8 >>>> [ 2.986291] [] device_driver_attach+0x84/0x90 >>>> [ 2.986293] [] __driver_attach+0xc8/0x128 >>>> [ 2.986295] [] bus_for_each_dev+0x74/0xd8 >>>> [ 2.986297] [] bus_add_driver+0x170/0x250 >>>> [ 2.986299] [] driver_register+0x84/0x150 >>>> [ 2.986301] [] do_one_initcall+0x98/0x458 >>>> [ 2.986303] [] kernel_init_freeable+0x2c0/0x36c >>>> [ 2.986305] [] kernel_init+0x10/0x128 >>>> [ 2.986307] [] ret_from_kernel_thread+0x14/0x1c >>>> >>>> Signed-off-by: Xingxing Su >>>> --- >>>> drivers/pci/access.c | 3 --- >>>> 1 file changed, 3 deletions(-) >>>> >>>> diff --git a/drivers/pci/access.c b/drivers/pci/access.c >>>> index 79c4a2e..b3fc164 100644 >>>> --- a/drivers/pci/access.c >>>> +++ b/drivers/pci/access.c >>>> @@ -160,9 +160,6 @@ 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); >>> >>> We just changed this printk (see [1]), but I think we still have this >>> lockdep problem even after Mark's change. So I guess we need another >>> think about this. >>> >>> Maybe we can print something when registering pci_ops that use >>> pci_generic_config_write32()? >> >> That was my suggestion, but as Mark pointed out that doesn't work if >> pci_generic_config_write32 is wrapped (which is 4 out of 8 cases). >> >> Also, 3 of the cases are only for the root bus (bridge). Are 32-bit >> writes to a bridge going to cause problems? For xgene, interestingly, >> with DT _write32 is needed, but for ACPI it is not (only _read32). I >> think xgene is practically dead though a few people still have >> systems, but likely xgene with DT is really dead. The ECAM case was >> for QCom server which is also pretty much dead. SA1100 nano-engine is >> really old and something only a few people have at most (Russell >> King). So ignoring all those, we're left with just loongson and iproc. >> Maybe just remove the warning? > > Sigh, removing it sounds like the best option. Given that we have to go by a list of drivers, how about we add another pci_bus_flags_t flag to indicate 32-bit configuration space accessors are used and key off that bit to issue the warning? -- Florian