From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 5CB19A09E4; Thu, 21 Jan 2021 11:46:19 +0100 (CET) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id CE4AD140CF7; Thu, 21 Jan 2021 11:46:18 +0100 (CET) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by mails.dpdk.org (Postfix) with ESMTP id F071E140CEF for ; Thu, 21 Jan 2021 11:46:16 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1611225976; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=4Wz/adDg9K9SE9zdVKdfBQF5+QFBwLHqy3FOLLWJ9lw=; b=ij7in+PeJ4ybbkS/2IUxzJqK5UoXH+VXXzETzOInPv2On8m33Aj8aPpagHudU+4w8LdxOP u9TN01fb0NSuCqgT1qFMzVBqBEd6++qx9zXypxCtzDOLN20TSK620xXeeIOfr3guA3XZVT 4ZUhlDOWwJDusZOf3DKKPMjBed/90/4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-91-mU5TrYB3Mwy6ZYKlNFIeJQ-1; Thu, 21 Jan 2021 05:46:14 -0500 X-MC-Unique: mU5TrYB3Mwy6ZYKlNFIeJQ-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 4A176E743; Thu, 21 Jan 2021 10:46:13 +0000 (UTC) Received: from [10.36.110.29] (unknown [10.36.110.29]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 132FC5D9D5; Thu, 21 Jan 2021 10:46:08 +0000 (UTC) To: Matan Azrad , David Marchand Cc: dev , dpdk stable References: <1609915409-272126-1-git-send-email-matan@nvidia.com> <746e905a-c394-44df-2c49-2afd59c05d9f@redhat.com> <1052520c-61e9-2135-bbad-9d009f52ce4b@redhat.com> <1c1fdabf-2588-2fd7-f5c4-dcb4e029ac35@redhat.com> From: Maxime Coquelin Message-ID: Date: Thu, 21 Jan 2021 11:46:07 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=maxime.coquelin@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-dev] [dpdk-stable] [PATCH] vdpa/mlx5: fix configuration mutex cleanup X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 1/14/21 4:23 PM, Matan Azrad wrote: > > > From: Maxime Coquelin >> On 1/14/21 2:09 PM, Matan Azrad wrote: >>> >>> >>> From: Maxime Coquelin >>>> Hi Matan, >>>> >>>> On 1/14/21 12:49 PM, Matan Azrad wrote: >>>>> Hi Maxime and David >>>>> >>>>> Thank you for Review. >>>>> >>>>> From: David Marchand >>>>>> On Fri, Jan 8, 2021 at 9:48 AM David Marchand >>>>>> wrote: >>>>>>>> I wonder if it would be possible and cleaner to disable >>>>>>>> cancellation on the thread while the mutex is held? >>>>> >>>>> Yes, we can cause thread to return by some global variable sync. >>>>> It is the same logic. >>>> >>>> No, that was not my suggestion. My suggestion is to block the thread >>>> cancellation while in the critical section, using pthread_setcancelstate(). >>> >>> Yes, Generally it is better to let the thread control his cancellation, either >> cancel itself or enabling\disabling cancellations. >>> >>> I don't see a reason to wait for the thread in current logic - the critical section >> is not important to be completed here. >> >> The reason I see is there are quite a few things done in this critical section. And >> if tomorrow someone add new things in it, he may not know the thread can be >> cancelled at any time, which could cause hard to debug issues. > > As I said, here it is not needed, this thread designed just to cause guest notifications. > > The optional future developer mistake can be done also outside the critical section in in any other place - we cannot protect it. > > The design choice is to close the thread fast. But why is it so urgent that it cannot been stopped cleanly? I don't think it would add seconds delay by doing it in a clean way. Thanks, Maxime >>> We just want to close the thread and to clean the mutex. >>> >>>>>>> +1 >>>>>> >>>>>> IEEE Std 1003.1-2001/Cor 2-2004, item XBD/TC2/D6/26 is applied, >>>>>> adding pthread_t to the list of types that are not required to be >>>>>> arithmetic types, thus allowing pthread_t to be defined as a structure. >>>>>> >>>>>> It would be better to leave pthread_t alone and not interpret it: >>>>>> >>>>>> if (priv->timer_tid) { >>>>>> pthread_cancel(priv->timer_tid); >>>>>> pthread_join(priv->timer_tid, &status); } >>>>>> priv->timer_tid = 0; >>>>> >>>>> >>>>> I'm not sure why you think it is better in this specific case. >>>>> The cancellation will close the thread in faster way, no need to >>>>> wait for the >>>> thread to close itself. >>>>> >>>>> >>>>>> >>>>>> -- >>>>>> David Marchand >>>>> >>> >