From patchwork Wed Oct 6 15:19:28 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hanna Czenczek X-Patchwork-Id: 12539547 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 908B8C433F5 for ; Wed, 6 Oct 2021 15:22:14 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 493C360FC0 for ; Wed, 6 Oct 2021 15:22:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 493C360FC0 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:55466 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mY8kH-0003vp-7p for qemu-devel@archiver.kernel.org; Wed, 06 Oct 2021 11:22:13 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:46472) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mY8hz-0001GY-Cw for qemu-devel@nongnu.org; Wed, 06 Oct 2021 11:19:51 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:44259) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mY8hw-0007C8-OG for qemu-devel@nongnu.org; Wed, 06 Oct 2021 11:19:50 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1633533587; 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=wkI3YtTJH0qbxN7CudcVoS+4zgvGczYKWRtJK0ClTOI=; b=cKhQg7PSMvtoykwSCWYHP8euXVOIupQ51tIi8mC5xcn3SDG4BzfDOEB+1tub0G1S+8wexe lNYMtGGcPT4wKsML2QL9gF6X7NQMd1KK+8f+keheUxhpASfc9DLxh1Xwhh52eHXdjeh5Gl MbCKH4gOJa7BKQi9wAKG+eQSKhrlY6U= 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-299-D7NhAiAzMT-4bldoB9DL7g-1; Wed, 06 Oct 2021 11:19:46 -0400 X-MC-Unique: D7NhAiAzMT-4bldoB9DL7g-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 A76A0104FC19; Wed, 6 Oct 2021 15:19:45 +0000 (UTC) Received: from localhost (unknown [10.39.193.194]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 40B805D9C6; Wed, 6 Oct 2021 15:19:45 +0000 (UTC) From: Hanna Reitz To: qemu-block@nongnu.org Subject: [PATCH v5 01/13] job: Context changes in job_completed_txn_abort() Date: Wed, 6 Oct 2021 17:19:28 +0200 Message-Id: <20211006151940.214590-2-hreitz@redhat.com> In-Reply-To: <20211006151940.214590-1-hreitz@redhat.com> References: <20211006151940.214590-1-hreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=hreitz@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=216.205.24.124; envelope-from=hreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.05, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Hanna Reitz , Vladimir Sementsov-Ogievskiy , Eric Blake , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Finalizing the job may cause its AioContext to change. This is noted by job_exit(), which points at job_txn_apply() to take this fact into account. However, job_completed() does not necessarily invoke job_txn_apply() (through job_completed_txn_success()), but potentially also job_completed_txn_abort(). The latter stores the context in a local variable, and so always acquires the same context at its end that it has released in the beginning -- which may be a different context from the one that job_exit() releases at its end. If it is different, qemu aborts ("qemu_mutex_unlock_impl: Operation not permitted"). Drop the local @outer_ctx variable from job_completed_txn_abort(), and instead re-acquire the actual job's context at the end of the function, so job_exit() will release the same. Signed-off-by: Hanna Reitz Reviewed-by: Vladimir Sementsov-Ogievskiy --- job.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) diff --git a/job.c b/job.c index e7a5d28854..810e6a2065 100644 --- a/job.c +++ b/job.c @@ -737,7 +737,6 @@ static void job_cancel_async(Job *job, bool force) static void job_completed_txn_abort(Job *job) { - AioContext *outer_ctx = job->aio_context; AioContext *ctx; JobTxn *txn = job->txn; Job *other_job; @@ -751,10 +750,14 @@ static void job_completed_txn_abort(Job *job) txn->aborting = true; job_txn_ref(txn); - /* We can only hold the single job's AioContext lock while calling + /* + * We can only hold the single job's AioContext lock while calling * job_finalize_single() because the finalization callbacks can involve - * calls of AIO_WAIT_WHILE(), which could deadlock otherwise. */ - aio_context_release(outer_ctx); + * calls of AIO_WAIT_WHILE(), which could deadlock otherwise. + * Note that the job's AioContext may change when it is finalized. + */ + job_ref(job); + aio_context_release(job->aio_context); /* Other jobs are effectively cancelled by us, set the status for * them; this job, however, may or may not be cancelled, depending @@ -769,6 +772,10 @@ static void job_completed_txn_abort(Job *job) } while (!QLIST_EMPTY(&txn->jobs)) { other_job = QLIST_FIRST(&txn->jobs); + /* + * The job's AioContext may change, so store it in @ctx so we + * release the same context that we have acquired before. + */ ctx = other_job->aio_context; aio_context_acquire(ctx); if (!job_is_completed(other_job)) { @@ -779,7 +786,12 @@ static void job_completed_txn_abort(Job *job) aio_context_release(ctx); } - aio_context_acquire(outer_ctx); + /* + * Use job_ref()/job_unref() so we can read the AioContext here + * even if the job went away during job_finalize_single(). + */ + aio_context_acquire(job->aio_context); + job_unref(job); job_txn_unref(txn); }