From nobody Sun Feb 8 21:47:47 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1631019756985535.7205563038948; Tue, 7 Sep 2021 06:02:36 -0700 (PDT) Received: from localhost ([::1]:33774 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mNakF-0008D9-PO for importer@patchew.org; Tue, 07 Sep 2021 09:02:35 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:47028) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mNaRE-0005WS-4W for qemu-devel@nongnu.org; Tue, 07 Sep 2021 08:42:56 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:48180) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mNaRB-0006EO-3G for qemu-devel@nongnu.org; Tue, 07 Sep 2021 08:42:54 -0400 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-340-JMcv082yOfmBc4Vd81hzZQ-1; Tue, 07 Sep 2021 08:42:50 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id CFD76100B385; Tue, 7 Sep 2021 12:42:49 +0000 (UTC) Received: from localhost (unknown [10.39.193.128]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 726D460BE5; Tue, 7 Sep 2021 12:42:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1631018572; 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=faB/gITp7FRDeFfaOaPTA1BKvprWvIs2cm5MA2K27n1yMz2ZIUN8JJnOYxU5ngXEOs3LXw WoWW0XMK8JkQNj45iW+G5P/N+I/aNtHiFkHMcHs+TkrooA2dm4hn81LGmCkBdsk/eqBhNn uRFpsDZ/TxHvfzKe4i3QoyBxV+4vUtw= X-MC-Unique: JMcv082yOfmBc4Vd81hzZQ-1 From: Hanna Reitz To: qemu-block@nongnu.org Subject: [PATCH v4 01/12] job: Context changes in job_completed_txn_abort() Date: Tue, 7 Sep 2021 14:42:34 +0200 Message-Id: <20210907124245.143492-2-hreitz@redhat.com> In-Reply-To: <20210907124245.143492-1-hreitz@redhat.com> References: <20210907124245.143492-1-hreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 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 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=hreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.391, 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+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) X-ZM-MESSAGEID: 1631019766675100001 Content-Type: text/plain; charset="utf-8" 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) =20 static void job_completed_txn_abort(Job *job) { - AioContext *outer_ctx =3D job->aio_context; AioContext *ctx; JobTxn *txn =3D job->txn; Job *other_job; @@ -751,10 +750,14 @@ static void job_completed_txn_abort(Job *job) txn->aborting =3D true; job_txn_ref(txn); =20 - /* 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); =20 /* 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 =3D 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 =3D 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); } =20 - 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); =20 job_txn_unref(txn); } --=20 2.31.1