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=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 C89F5C04AAF for ; Mon, 20 May 2019 12:18:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9EBFF20656 for ; Mon, 20 May 2019 12:18:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558354719; bh=ofEIYAS8+rvPfYlANzMOn0TgjZ0h4w0AB+vYOudGgtE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=z50djPEFqXShRRuMe5YBvcoTzP4IiF4ZvqXq6OWtokBR9iBf8IeYvAwRlRXBaGcvC oS5Xn3UsHzhn9tHK8SEoWo+yEZboJYfmR668K5nktFW0a6KpZacJeeFTt0LYR5DWop SKedHLf+jjCxHMYrEMMsyHEEWpoP36zMToy39x3U= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731934AbfETMSi (ORCPT ); Mon, 20 May 2019 08:18:38 -0400 Received: from mail.kernel.org ([198.145.29.99]:59734 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387725AbfETMSh (ORCPT ); Mon, 20 May 2019 08:18:37 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 14E36208C3; Mon, 20 May 2019 12:18:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558354716; bh=ofEIYAS8+rvPfYlANzMOn0TgjZ0h4w0AB+vYOudGgtE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=v81g+zm+KjoM2/7suwioOoBlqz3Wq8LidTX9hB5ALljZzPoRbAm3vA75mQAx9lQYU 7SXOALMavJVq1jibTePGaMTqxWkzcxt548vnkNqqr4GdR8iVn3wmXhUZrtecrKCpuf uvb7X9v3tASC4DkVndpiCbtz8J2jKtWhFALUpAXE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dexuan Cui , Lorenzo Pieralisi , Stephen Hemminger , Michael Kelley , Sasha Levin Subject: [PATCH 4.14 05/63] PCI: hv: Add pci_destroy_slot() in pci_devices_present_work(), if necessary Date: Mon, 20 May 2019 14:13:44 +0200 Message-Id: <20190520115231.834981202@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190520115231.137981521@linuxfoundation.org> References: <20190520115231.137981521@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org [ Upstream commit 340d455699400f2c2c0f9b3f703ade3085cdb501 ] When we hot-remove a device, usually the host sends us a PCI_EJECT message, and a PCI_BUS_RELATIONS message with bus_rel->device_count == 0. When we execute the quick hot-add/hot-remove test, the host may not send us the PCI_EJECT message if the guest has not fully finished the initialization by sending the PCI_RESOURCES_ASSIGNED* message to the host, so it's potentially unsafe to only depend on the pci_destroy_slot() in hv_eject_device_work() because the code path create_root_hv_pci_bus() -> hv_pci_assign_slots() is not called in this case. Note: in this case, the host still sends the guest a PCI_BUS_RELATIONS message with bus_rel->device_count == 0. In the quick hot-add/hot-remove test, we can have such a race before the code path pci_devices_present_work() -> new_pcichild_device() adds the new device into the hbus->children list, we may have already received the PCI_EJECT message, and since the tasklet handler hv_pci_onchannelcallback() may fail to find the "hpdev" by calling get_pcichild_wslot(hbus, dev_message->wslot.slot) hv_pci_eject_device() is not called; Later, by continuing execution create_root_hv_pci_bus() -> hv_pci_assign_slots() creates the slot and the PCI_BUS_RELATIONS message with bus_rel->device_count == 0 removes the device from hbus->children, and we end up being unable to remove the slot in hv_pci_remove() -> hv_pci_remove_slots() Remove the slot in pci_devices_present_work() when the device is removed to address this race. pci_devices_present_work() and hv_eject_device_work() run in the singled-threaded hbus->wq, so there is not a double-remove issue for the slot. We cannot offload hv_pci_eject_device() from hv_pci_onchannelcallback() to the workqueue, because we need the hv_pci_onchannelcallback() synchronously call hv_pci_eject_device() to poll the channel ringbuffer to work around the "hangs in hv_compose_msi_msg()" issue fixed in commit de0aa7b2f97d ("PCI: hv: Fix 2 hang issues in hv_compose_msi_msg()") Fixes: a15f2c08c708 ("PCI: hv: support reporting serial number as slot information") Signed-off-by: Dexuan Cui [lorenzo.pieralisi@arm.com: rewritten commit log] Signed-off-by: Lorenzo Pieralisi Reviewed-by: Stephen Hemminger Reviewed-by: Michael Kelley Cc: stable@vger.kernel.org Signed-off-by: Sasha Levin --- drivers/pci/host/pci-hyperv.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c index a5825bbcded72..f591de23f3d35 100644 --- a/drivers/pci/host/pci-hyperv.c +++ b/drivers/pci/host/pci-hyperv.c @@ -1824,6 +1824,10 @@ static void pci_devices_present_work(struct work_struct *work) hpdev = list_first_entry(&removed, struct hv_pci_dev, list_entry); list_del(&hpdev->list_entry); + + if (hpdev->pci_slot) + pci_destroy_slot(hpdev->pci_slot); + put_pcichild(hpdev, hv_pcidev_ref_initial); } -- 2.20.1