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Mon, 27 Feb 2023 15:57:27 -0500 Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-433-ndtPF59BOR29qc-BDQNpuA-1; Mon, 27 Feb 2023 15:57:14 -0500 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id B03633813F2B; Mon, 27 Feb 2023 20:57:13 +0000 (UTC) Received: from localhost (unknown [10.39.192.23]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2F1A3404BEC5; Mon, 27 Feb 2023 20:57:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1677531435; 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=NAE9hM9zaTwDQkfb8LozUrNwQHhptwbd7YSOI3y3kdk=; b=PrMYRoX5WAd/U4HOFVa0DwA+Y9Rm0tqn1Kz5RqmBek4SoIumdG4Nwfq+VXpJtprusvEdop 65UG06vQNBX5k46uOjxxhNodiTl8lI4uB2tG521r+qO7jHOoNszZG1glWy5YQG2jDeOqbV 4iqgvSG3jWQ1uylwChyFmVSm1hNyaZI= X-MC-Unique: ndtPF59BOR29qc-BDQNpuA-1 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Cc: Emanuele Giuseppe Esposito , qemu-block@nongnu.org, Hanna Reitz , Kevin Wolf , Paolo Bonzini , Stefan Hajnoczi Subject: [PATCH 2/3] block: make BlockBackend->disable_request_queuing atomic Date: Mon, 27 Feb 2023 15:57:03 -0500 Message-Id: <20230227205704.1910562-3-stefanha@redhat.com> In-Reply-To: <20230227205704.1910562-1-stefanha@redhat.com> References: <20230227205704.1910562-1-stefanha@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 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=170.10.129.124; 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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1677531513803100017 Content-Type: text/plain; charset="utf-8" This field is accessed by multiple threads without a lock. Use explicit qatomic_read()/qatomic_set() calls. There is no need for acquire/release because blk_set_disable_request_queuing() doesn't provide any guarantees (it helps that it's used at BlockBackend creation time and not when there is I/O in flight). Signed-off-by: Stefan Hajnoczi Reviewed-by: Hanna Czenczek --- block/block-backend.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/block/block-backend.c b/block/block-backend.c index f00bf2ab35..ec7eafd7fb 100644 --- a/block/block-backend.c +++ b/block/block-backend.c @@ -82,7 +82,7 @@ struct BlockBackend { =20 int quiesce_counter; /* atomic: written under BQL, read by other threa= ds */ CoQueue queued_requests; - bool disable_request_queuing; + bool disable_request_queuing; /* atomic */ =20 VMChangeStateEntry *vmsh; bool force_allow_inactivate; @@ -1232,7 +1232,7 @@ void blk_set_allow_aio_context_change(BlockBackend *b= lk, bool allow) void blk_set_disable_request_queuing(BlockBackend *blk, bool disable) { IO_CODE(); - blk->disable_request_queuing =3D disable; + qatomic_set(&blk->disable_request_queuing, disable); } =20 static int coroutine_fn GRAPH_RDLOCK @@ -1271,7 +1271,8 @@ static void coroutine_fn blk_wait_while_drained(Block= Backend *blk) { assert(blk->in_flight > 0); =20 - if (qatomic_read(&blk->quiesce_counter) && !blk->disable_request_queui= ng) { + if (qatomic_read(&blk->quiesce_counter) && + !qatomic_read(&blk->disable_request_queuing)) { blk_dec_in_flight(blk); qemu_co_queue_wait(&blk->queued_requests, NULL); blk_inc_in_flight(blk); --=20 2.39.2