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 1E929C678D5 for ; Tue, 7 Mar 2023 21:05:52 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pZeUH-0008A1-Fe; Tue, 07 Mar 2023 16:04:45 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pZeUF-00088k-Gt for qemu-devel@nongnu.org; Tue, 07 Mar 2023 16:04:43 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pZeUE-0002iW-1B for qemu-devel@nongnu.org; Tue, 07 Mar 2023 16:04:43 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1678223081; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=LKMFNjldcTsU810HycL2cuA/XyZV0C4BwRQGkbOqxBw=; b=ecAnkXkS9lPDjEVweATHeBhi675nFaEDrzNgn3Glc13KeXjlJgWadCMlxT0IOmAKnLCVlp aK266FZ6iZT2+Z25VraROAAefUYEaovgh8X9dZqcJPJoqDRpknXFvH5I8+HFkpN4WzDCLd 1OA7UXtDmEbXGJCIJKK4D5JtJDJBfkE= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-447-mOFH2HVqOMGfzyMLtFLm4w-1; Tue, 07 Mar 2023 16:04:38 -0500 X-MC-Unique: mOFH2HVqOMGfzyMLtFLm4w-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id EA170802D38; Tue, 7 Mar 2023 21:04:37 +0000 (UTC) Received: from localhost (unknown [10.39.192.86]) by smtp.corp.redhat.com (Postfix) with ESMTP id 50F2C2026D4B; Tue, 7 Mar 2023 21:04:37 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org Cc: Hanna Reitz , Kevin Wolf , qemu-block@nongnu.org, Emanuele Giuseppe Esposito , Paolo Bonzini , Stefan Hajnoczi Subject: [PATCH v2 3/3] block: protect BlockBackend->queued_requests with a lock Date: Tue, 7 Mar 2023 16:04:27 -0500 Message-Id: <20230307210427.269214-4-stefanha@redhat.com> In-Reply-To: <20230307210427.269214-1-stefanha@redhat.com> References: <20230307210427.269214-1-stefanha@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 Received-SPF: pass client-ip=170.10.129.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org The CoQueue API offers thread-safety via the lock argument that qemu_co_queue_wait() and qemu_co_enter_next() take. BlockBackend currently does not make use of the lock argument. This means that multiple threads submitting I/O requests can corrupt the CoQueue's QSIMPLEQ. Add a QemuMutex and pass it to CoQueue APIs so that the queue is protected. While we're at it, also assert that the queue is empty when the BlockBackend is deleted. Signed-off-by: Stefan Hajnoczi Reviewed-by: Hanna Czenczek --- block/block-backend.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/block/block-backend.c b/block/block-backend.c index 0cba4add20..8c90d19bf1 100644 --- a/block/block-backend.c +++ b/block/block-backend.c @@ -81,6 +81,7 @@ struct BlockBackend { QLIST_HEAD(, BlockBackendAioNotifier) aio_notifiers; int quiesce_counter; /* atomic: written under BQL, read by other threads */ + QemuMutex queued_requests_lock; /* protects queued_requests */ CoQueue queued_requests; bool disable_request_queuing; /* atomic */ @@ -368,6 +369,7 @@ BlockBackend *blk_new(AioContext *ctx, uint64_t perm, uint64_t shared_perm) block_acct_init(&blk->stats); + qemu_mutex_init(&blk->queued_requests_lock); qemu_co_queue_init(&blk->queued_requests); notifier_list_init(&blk->remove_bs_notifiers); notifier_list_init(&blk->insert_bs_notifiers); @@ -485,6 +487,8 @@ static void blk_delete(BlockBackend *blk) assert(QLIST_EMPTY(&blk->remove_bs_notifiers.notifiers)); assert(QLIST_EMPTY(&blk->insert_bs_notifiers.notifiers)); assert(QLIST_EMPTY(&blk->aio_notifiers)); + assert(qemu_co_queue_empty(&blk->queued_requests)); + qemu_mutex_destroy(&blk->queued_requests_lock); QTAILQ_REMOVE(&block_backends, blk, link); drive_info_del(blk->legacy_dinfo); block_acct_cleanup(&blk->stats); @@ -1273,9 +1277,16 @@ static void coroutine_fn blk_wait_while_drained(BlockBackend *blk) if (qatomic_read(&blk->quiesce_counter) && !qatomic_read(&blk->disable_request_queuing)) { + /* + * Take lock before decrementing in flight counter so main loop thread + * waits for us to enqueue ourselves before it can leave the drained + * section. + */ + qemu_mutex_lock(&blk->queued_requests_lock); blk_dec_in_flight(blk); - qemu_co_queue_wait(&blk->queued_requests, NULL); + qemu_co_queue_wait(&blk->queued_requests, &blk->queued_requests_lock); blk_inc_in_flight(blk); + qemu_mutex_unlock(&blk->queued_requests_lock); } } @@ -2607,9 +2618,12 @@ static void blk_root_drained_end(BdrvChild *child) if (blk->dev_ops && blk->dev_ops->drained_end) { blk->dev_ops->drained_end(blk->dev_opaque); } - while (qemu_co_enter_next(&blk->queued_requests, NULL)) { + qemu_mutex_lock(&blk->queued_requests_lock); + while (qemu_co_enter_next(&blk->queued_requests, + &blk->queued_requests_lock)) { /* Resume all queued requests */ } + qemu_mutex_unlock(&blk->queued_requests_lock); } } -- 2.39.2