From patchwork Tue Feb 18 14:06:48 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 11388547 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 5943D138D for ; Tue, 18 Feb 2020 14:10:44 +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 3052F21D56 for ; Tue, 18 Feb 2020 14:10:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="hVRl9kFX" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3052F21D56 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:35774 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j43aF-0004Jf-BT for patchwork-qemu-devel@patchwork.kernel.org; Tue, 18 Feb 2020 09:10:43 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:52706) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j43Xe-0006pG-9y for qemu-devel@nongnu.org; Tue, 18 Feb 2020 09:08:03 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1j43Xc-0001Nb-Gi for qemu-devel@nongnu.org; Tue, 18 Feb 2020 09:08:01 -0500 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:22399 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1j43Xc-0001N6-Ad for qemu-devel@nongnu.org; Tue, 18 Feb 2020 09:08:00 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1582034879; 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=biH/DTlLPMH9qridvWjKQ2juHyE3xZFWc9acj2tyg1k=; b=hVRl9kFXmzKH7okAL3F8gKIKYTxzN6allyrh8HfNywyHFzUTLECDACSAE7oYfFXsf80MeR mpsB52RoEkVcIeS0V8/kIVuiavNhIo5Nx1nJLjyavwlq6hYD4zZMuyQm5c0oFlyDV3o8Fr NomcaXzlDdlq0YE+tGjTD/L9614Sxco= 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-436-j8aIpXg2OTGs5YKVYMP9WQ-1; Tue, 18 Feb 2020 09:07:55 -0500 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 99B93101FC8B; Tue, 18 Feb 2020 14:07:54 +0000 (UTC) Received: from linux.fritz.box.com (ovpn-117-181.ams2.redhat.com [10.36.117.181]) by smtp.corp.redhat.com (Postfix) with ESMTP id 953F48B54F; Tue, 18 Feb 2020 14:07:53 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Subject: [PULL 02/36] mirror: Don't let an operation wait for itself Date: Tue, 18 Feb 2020 15:06:48 +0100 Message-Id: <20200218140722.23876-3-kwolf@redhat.com> In-Reply-To: <20200218140722.23876-1-kwolf@redhat.com> References: <20200218140722.23876-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-MC-Unique: j8aIpXg2OTGs5YKVYMP9WQ-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.61 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: kwolf@redhat.com, peter.maydell@linaro.org, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" mirror_wait_for_free_in_flight_slot() just picks a random operation to wait for. However, when mirror_co_read() waits for free slots, its MirrorOp is already in s->ops_in_flight, so if not enough slots are immediately available, an operation can end up waiting for itself to complete, which results in a hang. Fix this by passing the current MirrorOp and skipping this operation when picking an operation to wait for. Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1794692 Signed-off-by: Kevin Wolf Reviewed-by: Eric Blake --- block/mirror.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/block/mirror.c b/block/mirror.c index 8959e4255f..cacbc70014 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -283,11 +283,14 @@ static int mirror_cow_align(MirrorBlockJob *s, int64_t *offset, } static inline void coroutine_fn -mirror_wait_for_any_operation(MirrorBlockJob *s, bool active) +mirror_wait_for_any_operation(MirrorBlockJob *s, MirrorOp *self, bool active) { MirrorOp *op; QTAILQ_FOREACH(op, &s->ops_in_flight, next) { + if (self == op) { + continue; + } /* Do not wait on pseudo ops, because it may in turn wait on * some other operation to start, which may in fact be the * caller of this function. Since there is only one pseudo op @@ -302,10 +305,10 @@ mirror_wait_for_any_operation(MirrorBlockJob *s, bool active) } static inline void coroutine_fn -mirror_wait_for_free_in_flight_slot(MirrorBlockJob *s) +mirror_wait_for_free_in_flight_slot(MirrorBlockJob *s, MirrorOp *self) { /* Only non-active operations use up in-flight slots */ - mirror_wait_for_any_operation(s, false); + mirror_wait_for_any_operation(s, self, false); } /* Perform a mirror copy operation. @@ -348,7 +351,7 @@ static void coroutine_fn mirror_co_read(void *opaque) while (s->buf_free_count < nb_chunks) { trace_mirror_yield_in_flight(s, op->offset, s->in_flight); - mirror_wait_for_free_in_flight_slot(s); + mirror_wait_for_free_in_flight_slot(s, op); } /* Now make a QEMUIOVector taking enough granularity-sized chunks @@ -555,7 +558,7 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) while (s->in_flight >= MAX_IN_FLIGHT) { trace_mirror_yield_in_flight(s, offset, s->in_flight); - mirror_wait_for_free_in_flight_slot(s); + mirror_wait_for_free_in_flight_slot(s, pseudo_op); } if (s->ret < 0) { @@ -609,7 +612,7 @@ static void mirror_free_init(MirrorBlockJob *s) static void coroutine_fn mirror_wait_for_all_io(MirrorBlockJob *s) { while (s->in_flight > 0) { - mirror_wait_for_free_in_flight_slot(s); + mirror_wait_for_free_in_flight_slot(s, NULL); } } @@ -794,7 +797,7 @@ static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s) if (s->in_flight >= MAX_IN_FLIGHT) { trace_mirror_yield(s, UINT64_MAX, s->buf_free_count, s->in_flight); - mirror_wait_for_free_in_flight_slot(s); + mirror_wait_for_free_in_flight_slot(s, NULL); continue; } @@ -947,7 +950,7 @@ static int coroutine_fn mirror_run(Job *job, Error **errp) /* Do not start passive operations while there are active * writes in progress */ while (s->in_active_write_counter) { - mirror_wait_for_any_operation(s, true); + mirror_wait_for_any_operation(s, NULL, true); } if (s->ret < 0) { @@ -973,7 +976,7 @@ static int coroutine_fn mirror_run(Job *job, Error **errp) if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 || (cnt == 0 && s->in_flight > 0)) { trace_mirror_yield(s, cnt, s->buf_free_count, s->in_flight); - mirror_wait_for_free_in_flight_slot(s); + mirror_wait_for_free_in_flight_slot(s, NULL); continue; } else if (cnt != 0) { delay_ns = mirror_iteration(s);