From patchwork Mon May 23 17:15:17 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sheng Bi X-Patchwork-Id: 12859281 X-Patchwork-Delegate: bhelgaas@google.com 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 603CFC433FE for ; Mon, 23 May 2022 17:17:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239908AbiEWRRS (ORCPT ); Mon, 23 May 2022 13:17:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34058 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241173AbiEWRRJ (ORCPT ); Mon, 23 May 2022 13:17:09 -0400 Received: from mail-pj1-x102d.google.com (mail-pj1-x102d.google.com [IPv6:2607:f8b0:4864:20::102d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5B43D21E18; Mon, 23 May 2022 10:16:56 -0700 (PDT) Received: by mail-pj1-x102d.google.com with SMTP id z11so4810569pjc.3; Mon, 23 May 2022 10:16:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=8ZnKZoJrCw++R1qQpo4hgDWev0CwMVPdkg70pBxSDPs=; b=SWLxCg+JHh1EmVh/YW54O8CBi97MTi0/1JM5ILiPhIyGHO1RMktyLeQBNcTEMf6D4h WWX1DWAgTQSR6AwH5G/J6S5nEU2i8LLyz9X7y3MX83wjyH3gxtEqZFfK4FPanivITjXu vh4rhhqq0T8T69QwnEnY3Y77b4l+Ijn5ctqRvLJLfkPYdxSoQNeGTcnwQWKPSDn6VIF4 33wUxPDXKvmp0g0QWyLFiF1A1ttC33oT9I3PKui+Z2jOT8HRfM50AQ0n/bQW+fQNlCDh DDhuVMlIAH99fHaejkbQm7i6ycS4NSJKe47o3pCuSpoFcDPVKGxPYi6rFs3eOQTD8gbM 1jug== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=8ZnKZoJrCw++R1qQpo4hgDWev0CwMVPdkg70pBxSDPs=; b=2X6wwCojgbE/oyCXaZfariw32fqfLCXuhFVeOlDDUU2Ti+ux9abPvLW7qvYTId9P3u qqCaGPOXi1p+Z0Z9N1bh8fuXONUDms//ElFbqwC96Uyqzpo8L5V8+NItgoXRI8ihTe4O Czdh87g4maj5xIl3uv9PMYaPKB5lIhCax6JSadh/hRtJ1JUqZyq8Qmwm9KipP/tbUe/7 bnBJXToH76kVHl95BaGlmraCHqwZopuisIfllCDaMvmJl244axpOkQT9aaYwMdMzd14w Qep2pPhWjK1teACVM63WSqTKcjI52vLqHFB4Z0Q44CNQXfyd/eev1pY2FciuZ5QdGusH EzVQ== X-Gm-Message-State: AOAM530z5WlgzDM6Nxn25rG4BbrcBDKDzffOn7PVIVlsRIeJHW3HGnNP 2A7aIWsend3aZcU7sO6VhT2J5/qcW0x4xA== X-Google-Smtp-Source: ABdhPJzAFYIctogy39e+t4ny6sLP7bQRcD59ohd2F8F32KypIHkS67if1nnOaBVw9Ptgs5jVSjU8DA== X-Received: by 2002:a17:902:b214:b0:161:f6d8:45cd with SMTP id t20-20020a170902b21400b00161f6d845cdmr16367154plr.95.1653326137063; Mon, 23 May 2022 10:15:37 -0700 (PDT) Received: from localhost.localdomain ([103.126.24.15]) by smtp.gmail.com with ESMTPSA id i198-20020a6287cf000000b005180c127200sm7604646pfe.24.2022.05.23.10.15.34 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 23 May 2022 10:15:36 -0700 (PDT) From: Sheng Bi To: helgaas@kernel.org, bhelgaas@google.com, alex.williamson@redhat.com, lukas@wunner.de Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Sheng Bi Subject: [PATCH v3] PCI: Fix no-op wait after secondary bus reset Date: Tue, 24 May 2022 01:15:17 +0800 Message-Id: <20220523171517.32407-1-windy.bi.enflame@gmail.com> X-Mailer: git-send-email 2.36.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org pci_bridge_secondary_bus_reset() triggers SBR followed by 1 second sleep, and then uses pci_dev_wait() for waiting device ready. The dev parameter passes to the wait function is currently the bridge itself, but not the device been reset. If we call pci_bridge_secondary_bus_reset() to trigger SBR to a device, there is 1 second sleep but not waiting device ready, since the bridge is always ready while resetting downstream devices. pci_dev_wait() here is a no-op actually. This would be risky in the case which the device becomes ready after more than 1 second, especially while hotplug enabled. The late coming hotplug event after 1 second will trigger hotplug module to remove/re-insert the device. Instead of waiting ready of bridge itself, changing to wait all the downstream devices become ready with timeout PCIE_RESET_READY_POLL_MS after SBR, considering all downstream devices are affected during SBR. Once one of the devices doesn't reappear within the timeout, return -ENOTTY to indicate SBR doesn't complete successfully. Fixes: 6b2f1351af56 ("PCI: Wait for device to become ready after secondary bus reset") Signed-off-by: Sheng Bi Reviewed-by: Lukas Wunner --- drivers/pci/pci.c | 30 +++++++++++++++++++++++++++++- 1 file changed, 29 insertions(+), 1 deletion(-) base-commit: 617c8a1e527fadaaec3ba5bafceae7a922ebef7e diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index eb7c0a08ff57..4653a9ae6e5b 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -5049,6 +5049,34 @@ void pci_bridge_wait_for_secondary_bus(struct pci_dev *dev) } } +static int pci_bridge_secondary_bus_wait(struct pci_dev *bridge, int timeout) +{ + struct pci_dev *dev; + unsigned long start_jiffies; + + down_read(&pci_bus_sem); + + if (!bridge->subordinate || list_empty(&bridge->subordinate->devices)) { + up_read(&pci_bus_sem); + return 0; + } + + list_for_each_entry(dev, &bridge->subordinate->devices, bus_list) { + start_jiffies = jiffies; + + if (timeout < 0 || pci_dev_wait(dev, "bus reset", timeout)) { + up_read(&pci_bus_sem); + return -ENOTTY; + } + + timeout -= jiffies_to_msecs(jiffies - start_jiffies); + } + + up_read(&pci_bus_sem); + + return 0; +} + void pci_reset_secondary_bus(struct pci_dev *dev) { u16 ctrl; @@ -5092,7 +5120,7 @@ int pci_bridge_secondary_bus_reset(struct pci_dev *dev) { pcibios_reset_secondary_bus(dev); - return pci_dev_wait(dev, "bus reset", PCIE_RESET_READY_POLL_MS); + return pci_bridge_secondary_bus_wait(dev, PCIE_RESET_READY_POLL_MS); } EXPORT_SYMBOL_GPL(pci_bridge_secondary_bus_reset);