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{ "id": 819325, "url": "http://patchwork.ozlabs.org/api/covers/819325/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-pci/cover/20170927214220.41216-1-gvaradar@cisco.com/", "project": { "id": 28, "url": "http://patchwork.ozlabs.org/api/projects/28/?format=api", "name": "Linux PCI development", "link_name": "linux-pci", "list_id": "linux-pci.vger.kernel.org", "list_email": "linux-pci@vger.kernel.org", "web_url": null, "scm_url": null, "webscm_url": null, "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<20170927214220.41216-1-gvaradar@cisco.com>", "list_archive_url": null, "date": "2017-09-27T21:42:16", "name": "[0/4] pci aer: fix deadlock in do_recovery", "submitter": { "id": 46073, "url": "http://patchwork.ozlabs.org/api/people/46073/?format=api", "name": "Govindarajulu Varadarajan", "email": "gvaradar@cisco.com" }, "mbox": "http://patchwork.ozlabs.org/project/linux-pci/cover/20170927214220.41216-1-gvaradar@cisco.com/mbox/", "series": [ { "id": 5455, "url": "http://patchwork.ozlabs.org/api/series/5455/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-pci/list/?series=5455", "date": "2017-09-27T21:42:16", "name": "pci aer: fix deadlock in do_recovery", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/5455/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/covers/819325/comments/", "headers": { "Return-Path": "<linux-pci-owner@vger.kernel.org>", "X-Original-To": "incoming@patchwork.ozlabs.org", "Delivered-To": "patchwork-incoming@bilbo.ozlabs.org", "Authentication-Results": [ "ozlabs.org;\n\tspf=none (mailfrom) smtp.mailfrom=vger.kernel.org\n\t(client-ip=209.132.180.67; helo=vger.kernel.org;\n\tenvelope-from=linux-pci-owner@vger.kernel.org;\n\treceiver=<UNKNOWN>)", "ozlabs.org; dkim=pass (1024-bit key;\n\tunprotected) header.d=cisco.com header.i=@cisco.com\n\theader.b=\"CbXxmC8E\"; dkim-atps=neutral" ], "Received": [ "from vger.kernel.org (vger.kernel.org [209.132.180.67])\n\tby ozlabs.org (Postfix) with ESMTP id 3y2Wkw5S0wz9t67\n\tfor <incoming@patchwork.ozlabs.org>;\n\tThu, 28 Sep 2017 07:52:24 +1000 (AEST)", "(majordomo@vger.kernel.org) by vger.kernel.org via listexpand\n\tid S1752092AbdI0VwX (ORCPT <rfc822;incoming@patchwork.ozlabs.org>);\n\tWed, 27 Sep 2017 17:52:23 -0400", "from rcdn-iport-4.cisco.com ([173.37.86.75]:6641 \"EHLO\n\trcdn-iport-4.cisco.com\" rhost-flags-OK-OK-OK-OK) by vger.kernel.org\n\twith ESMTP id S1751905AbdI0VwW (ORCPT\n\t<rfc822; linux-pci@vger.kernel.org>); Wed, 27 Sep 2017 17:52:22 -0400", "from alln-core-6.cisco.com ([173.36.13.139])\n\tby rcdn-iport-4.cisco.com with ESMTP/TLS/DHE-RSA-AES256-SHA;\n\t27 Sep 2017 21:42:57 +0000", "from a6.cisco.com (arch-kvm-vm.cisco.com [10.193.184.6])\n\t(authenticated bits=0)\n\tby alln-core-6.cisco.com (8.14.5/8.14.5) with ESMTP id v8RLgpwe021066\n\t(version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO);\n\tWed, 27 Sep 2017 21:42:57 GMT" ], "X-Greylist": "delayed 563 seconds by postgrey-1.27 at vger.kernel.org;\n\tWed, 27 Sep 2017 17:52:22 EDT", "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/simple;\n\td=cisco.com; i=@cisco.com; l=2066; q=dns/txt; s=iport;\n\tt=1506549142; x=1507758742;\n\th=from:to:cc:subject:date:message-id;\n\tbh=B4XupCfpP5J1cTVeghWBD/DwSnoP6Gmur28KI/bnY98=;\n\tb=CbXxmC8E07Enh/hn9RxZmo2NdGu0Ka4qyIK9qecuLIaDn9XwBDSSPUYE\n\tm96XBB7GIvNJKOa4b/YF3nEMBtSl0JI/7Yfq/mNGOu0H+vXMIhi3ZuYOP\n\tbpf9z6j1c7SGiSFuAq8bv7hGqctigw+Zc85poQxpZo7sh44ErykTLw2cR w=;", "X-IronPort-AV": "E=Sophos;i=\"5.42,446,1500940800\"; d=\"scan'208\";a=\"300794013\"", "From": "Govindarajulu Varadarajan <gvaradar@cisco.com>", "To": "benve@cisco.com, bhelgaas@google.com, linux-pci@vger.kernel.org,\n\tlinux-kernel@vger.kernel.org, jlbec@evilplan.org, hch@lst.de,\n\tmingo@redhat.com, peterz@infradead.org", "Cc": "Govindarajulu Varadarajan <gvaradar@cisco.com>", "Subject": "[PATCH 0/4] pci aer: fix deadlock in do_recovery", "Date": "Wed, 27 Sep 2017 14:42:16 -0700", "Message-Id": "<20170927214220.41216-1-gvaradar@cisco.com>", "X-Mailer": "git-send-email 2.14.1", "X-Authenticated-User": "gvaradar@cisco.com", "Sender": "linux-pci-owner@vger.kernel.org", "Precedence": "bulk", "List-ID": "<linux-pci.vger.kernel.org>", "X-Mailing-List": "linux-pci@vger.kernel.org" }, "content": "I am seeing a dead lock while loading enic driver with sriov enabled.\n\nCPU0\t\t\t\t\tCPU1\n---------------------------------------------------------------------\n__driver_attach()\ndevice_lock(&dev->mutex) <--- device mutex lock here\ndriver_probe_device()\npci_enable_sriov()\npci_iov_add_virtfn()\npci_device_add()\n\t\t\t\t\taer_isr()\t\t<--- pci aer error\n\t\t\t\t\tdo_recovery()\n\t\t\t\t\tbroadcast_error_message()\n\t\t\t\t\tpci_walk_bus()\n\t\t\t\t\tdown_read(&pci_bus_sem) <--- rd sem\ndown_write(&pci_bus_sem) <-- stuck on wr sem\n\t\t\t\t\treport_error_detected()\n\t\t\t\t\tdevice_lock(&dev->mutex)<--- DEAD LOCK\n\nThis can also happen when aer error occurs while pci_dev->sriov_config() is\ncalled.\n\nOnly fix I could think of is to lock &pci_bus_sem and try locking all\ndevice->mutex under that pci_bus. If it fails, unlock all device->mutex\nand &pci_bus_sem and try again. This approach seems to be hackish and I\ndo not have better solution. I would like to open the discussion for\nthis.\n\nPath 1 and 2 are code refactoring for pci locking api. Patch 3 fixes the\nissue.\n\nWith current fix, we hold mutex lock of parent device and all the\ndevices under the bus. This can exceed the size of held_locks in lockdep\nif number of devices (VFs) exceed 48. Patch 4 extends this 63, max\nsupported by lockdep.\n\nGovindarajulu Varadarajan (4):\n pci: introduce __pci_walk_bus for caller with pci_bus_sem held\n pci: code refactor pci_bus_lock/unlock/trylock\n pci aer: fix deadlock in do_recovery\n lockdep: make MAX_LOCK_DEPTH configurable from Kconfig\n\n drivers/pci/bus.c | 13 ++++++++--\n drivers/pci/pci.c | 38 ++++++++++++++++++++---------\n drivers/pci/pcie/aer/aerdrv_core.c | 50 ++++++++++++++++++++++++++++++--------\n fs/configfs/inode.c | 2 +-\n include/linux/pci.h | 18 ++++++++++++++\n include/linux/sched.h | 3 +--\n kernel/locking/lockdep.c | 13 +++++-----\n lib/Kconfig.debug | 10 ++++++++\n 8 files changed, 115 insertions(+), 32 deletions(-)" }