From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by dpdk.org (Postfix) with ESMTP id 60D3D2B94 for ; Wed, 7 Nov 2018 07:15:09 +0100 (CET) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga107.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 06 Nov 2018 22:15:08 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.54,474,1534834800"; d="scan'208";a="106564272" Received: from jguo15x-mobl.ccr.corp.intel.com (HELO [10.67.68.85]) ([10.67.68.85]) by orsmga002.jf.intel.com with ESMTP; 06 Nov 2018 22:15:05 -0800 To: Matan Azrad , "konstantin.ananyev@intel.com" , "anatoly.burakov@intel.com" , Thomas Monjalon , "bernard.iremonger@intel.com" , "jingjing.wu@intel.com" , "wenzhuo.lu@intel.com" Cc: "ferruh.yigit@intel.com" , "dev@dpdk.org" , "helin.zhang@intel.com" , "shaopeng.he@intel.com" References: <1541484436-91320-1-git-send-email-jia.guo@intel.com> <1541484436-91320-3-git-send-email-jia.guo@intel.com> From: Jeff Guo Message-ID: Date: Wed, 7 Nov 2018 14:15:05 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Subject: Re: [dpdk-dev] [PATCH 2/3] vfio: fix to add handler lock for hot-unplug X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 07 Nov 2018 06:15:10 -0000 On 11/6/2018 2:23 PM, Matan Azrad wrote: > Hi Jeff > > Can you detail more in the commit log that we can understand the synchronization problematic scenario. And how does this commit fix it? > Please check my reply in the 1/3 mail. And explain more here is that, when device be hot-unplugged in vfio, the req notifier will invoked, then user space could release device resource in user space side, then vfio check that the device be released out from the device group, it will take the device control again and trigger the device kernel release processing, at the mean time it will sent remove uevent to user space. Here although the req handler seems will always process before uevent handler, but even for fast path and slow path protection of device accessing when device is removing , it should also be need. what do you think about that? >> -----Original Message----- >> From: Jeff Guo >> Sent: Tuesday, November 6, 2018 8:07 AM >> To: konstantin.ananyev@intel.com; anatoly.burakov@intel.com; Thomas >> Monjalon ; bernard.iremonger@intel.com; >> jingjing.wu@intel.com; wenzhuo.lu@intel.com >> Cc: ferruh.yigit@intel.com; dev@dpdk.org; jia.guo@intel.com; >> helin.zhang@intel.com; Matan Azrad ; >> shaopeng.he@intel.com >> Subject: [PATCH 2/3] vfio: fix to add handler lock for hot-unplug >> >> This patch add hot-unplug handler lock and unlock in device request handler >> when process bus and device resource, in order to avoid the synchronization >> issue when device be hot-unplugged. >> >> Fixes: c115fd000c32 ("vfio: handle hotplug request notifier") >> Signed-off-by: Jeff Guo >> --- >> drivers/bus/pci/linux/pci_vfio.c | 14 +++++++++++++- >> 1 file changed, 13 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/bus/pci/linux/pci_vfio.c b/drivers/bus/pci/linux/pci_vfio.c >> index 305cc06..d2c8410 100644 >> --- a/drivers/bus/pci/linux/pci_vfio.c >> +++ b/drivers/bus/pci/linux/pci_vfio.c >> @@ -19,6 +19,7 @@ >> #include >> #include >> #include >> +#include >> >> #include "eal_filesystem.h" >> >> @@ -35,6 +36,14 @@ >> * This file is only compiled if CONFIG_RTE_EAL_VFIO is set to "y". >> */ >> >> +/* >> + * spinlock for device hot-unplug failure handling. If it try to access >> +bus or >> + * device, such as handle sigbus on bus or handle memory failure for >> +device >> + * just need to use this lock. It could protect the bus and the device >> +to avoid >> + * race condition. >> + */ >> +static rte_spinlock_t failure_handle_lock = RTE_SPINLOCK_INITIALIZER; >> + >> #ifdef VFIO_PRESENT >> >> #ifndef PAGE_SIZE >> @@ -289,11 +298,12 @@ pci_vfio_req_handler(void *param) >> int ret; >> struct rte_device *device = (struct rte_device *)param; >> >> + rte_spinlock_lock(&failure_handle_lock); >> bus = rte_bus_find_by_device(device); >> if (bus == NULL) { >> RTE_LOG(ERR, EAL, "Cannot find bus for device (%s)\n", >> device->name); >> - return; >> + goto handle_end; >> } >> >> /* >> @@ -306,6 +316,8 @@ pci_vfio_req_handler(void *param) >> RTE_LOG(ERR, EAL, >> "Can not handle hot-unplug for device (%s)\n", >> device->name); >> +handle_end: >> + rte_spinlock_unlock(&failure_handle_lock); >> } >> >> /* enable notifier (only enable req now) */ >> -- >> 2.7.4