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 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 376C5C433F5 for ; Wed, 19 Jan 2022 11:12:11 +0000 (UTC) Received: from localhost ([::1]:52186 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nA8ss-00035i-6W for qemu-devel@archiver.kernel.org; Wed, 19 Jan 2022 06:12:10 -0500 Received: from eggs.gnu.org ([209.51.188.92]:50112) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nA8q2-0001ie-7T; Wed, 19 Jan 2022 06:09:19 -0500 Received: from [2a00:1450:4864:20::336] (port=56070 helo=mail-wm1-x336.google.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1nA8pz-0006PD-Lb; Wed, 19 Jan 2022 06:09:13 -0500 Received: by mail-wm1-x336.google.com with SMTP id c66so4636560wma.5; Wed, 19 Jan 2022 03:09:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=acG2kxGvIAZAVaUEg8N0rUPMrz8m+39nInkf7vkXviQ=; b=SYEQiUfdduGxHtJSmmsy0oPUFvqeTvSihsqJBbBqEK5rVCH1TvRAN/nh4kbw0X2i4B WSiGrf2y8pX+moP0kOK1JzcXD6OkmW1iCoAXmwITyz/PU+0zyshfEqAhpro8chGDaJsy zcfO8rzVviJKX5743JAhAuVftX9deNYwDQTjy6QhWmUasXlL5NkdTkwoCpG50hbFVCSM 1nKL1Y/ZbBnZUUrHFOHiAj36QqChrWACM7yMflkYbxzlIciV1Aqhz0qzOS1w78bfrgIF NWEZ89PlODYB7/uDguB05GksJrWKoTsM+mueV4qFsPf3llQ/x10/6Bxg8ZY+A5krt+Rx OXCg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:message-id:date:mime-version:user-agent :subject:content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=acG2kxGvIAZAVaUEg8N0rUPMrz8m+39nInkf7vkXviQ=; b=CKNKJp10Nt2OYWSjdiZfShKZ02u/UZj9vyokYvYsoHC9P4Bb9o03VgUX2yuugvc/YN yY7NsqjuZzbCoRB0l3n2JH83k2fFvUAiWEsrgfI8OjkgqkUKGrfvlrhRiOibrb8pK9FC f88m67VTYCnkdJDf9HpnHV6DwNZfNfmeDcy2EiAFxcS1H5jCUnS9ol3L2Wa25vTgo/e9 v7IqxWOHgqqVqnJtIRRrpyNNsNrCc7+hWrQBHVzCj7CkBWvKzTjvIbhBImfnJjoodYLC AOEd8lapXS0W+BSJ1LwLYWNwMqD0gKGEX93sC3S5iH/pPlo1uiuSIUc0fLXev3nlS2p7 o69w== X-Gm-Message-State: AOAM532kEaatXNDOgi8w89JKBiVFIKzmKJKiHs7jUj5XNImhxH0bwJaM PuokZPY0B+Aiy1iJWB7n8TY= X-Google-Smtp-Source: ABdhPJzi7avPF6eu+qX01owUMTRinuarklKGr/l+R+IDQXbsuV+7BMTQwjiIEaiVtV8zNJ5VtP272g== X-Received: by 2002:a5d:660a:: with SMTP id n10mr5655407wru.40.1642590549098; Wed, 19 Jan 2022 03:09:09 -0800 (PST) Received: from ?IPV6:2001:b07:6468:f312:c8dd:75d4:99ab:290a? ([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.googlemail.com with ESMTPSA id f5sm4793492wmf.47.2022.01.19.03.09.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 19 Jan 2022 03:09:08 -0800 (PST) Message-ID: Date: Wed, 19 Jan 2022 12:09:06 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 Subject: Re: [PATCH v3 09/16] jobs: remove aiocontext locks since the functions are under BQL Content-Language: en-US To: Emanuele Giuseppe Esposito , qemu-block@nongnu.org References: <20220105140208.365608-1-eesposit@redhat.com> <20220105140208.365608-10-eesposit@redhat.com> From: Paolo Bonzini In-Reply-To: <20220105140208.365608-10-eesposit@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Host-Lookup-Failed: Reverse DNS lookup failed for 2a00:1450:4864:20::336 (failed) Received-SPF: pass client-ip=2a00:1450:4864:20::336; envelope-from=paolo.bonzini@gmail.com; helo=mail-wm1-x336.google.com X-Spam_score_int: -6 X-Spam_score: -0.7 X-Spam_bar: / X-Spam_report: (-0.7 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FORGED_FROMDOMAIN=0.249, FREEMAIL_FROM=0.001, HEADER_FROM_DIFFERENT_DOMAINS=0.248, NICE_REPLY_A=-0.001, PDS_HP_HELO_NORDNS=0.001, RCVD_IN_DNSWL_NONE=-0.0001, RDNS_NONE=0.793, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Fam Zheng , Vladimir Sementsov-Ogievskiy , Wen Congyang , Xie Changlong , Markus Armbruster , qemu-devel@nongnu.org, Hanna Reitz , Stefan Hajnoczi , John Snow Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 1/5/22 15:02, Emanuele Giuseppe Esposito wrote: > In preparation to the job_lock/unlock patch, remove these > aiocontext locks. > The main reason these two locks are removed here is because > they are inside a loop iterating on the jobs list. Once the > job_lock is added, it will have to protect the whole loop, > wrapping also the aiocontext acquire/release. > > We don't want this, as job_lock can only be *wrapped by* > the aiocontext lock, and not vice-versa, to avoid deadlocks. Better to avoid the passive: "must be taken inside the AioContext lock, and taking it outside would cause deadlocks". Also add a note about the lock hierarchy to patch 1. > @@ -3707,15 +3707,11 @@ BlockJobInfoList *qmp_query_block_jobs(Error **errp) > > for (job = block_job_next(NULL); job; job = block_job_next(job)) { > BlockJobInfo *value; > - AioContext *aio_context; > > if (block_job_is_internal(job)) { > continue; > } block_job_next, block_job_query, etc. do not have the _locked suffix. Is this because all block_job_ functions need the job_mutex held, or just laziness? :) Paolo > - aio_context = blk_get_aio_context(job->blk); > - aio_context_acquire(aio_context); > value = block_job_query(job, errp); > - aio_context_release(aio_context); > if (!value) { > qapi_free_BlockJobInfoList(head); > return NULL; > diff --git a/job-qmp.c b/job-qmp.c > index de4120a1d4..f6f9840436 100644 > --- a/job-qmp.c > +++ b/job-qmp.c > @@ -173,15 +173,11 @@ JobInfoList *qmp_query_jobs(Error **errp) > > for (job = job_next_locked(NULL); job; job = job_next_locked(job)) { > JobInfo *value; > - AioContext *aio_context; > > if (job_is_internal(job)) { > continue; > } > - aio_context = job->aio_context; > - aio_context_acquire(aio_context); > value = job_query_single(job, errp); > - aio_context_release(aio_context); > if (!value) { > qapi_free_JobInfoList(head); > return NULL;