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 X-Spam-Level: X-Spam-Status: No, score=-15.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 435ADC4743C for ; Fri, 4 Jun 2021 17:18:10 +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 0ECBC6140C for ; Fri, 4 Jun 2021 17:18:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0ECBC6140C 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+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:42956 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lpDST-0004Ix-7l for qemu-devel@archiver.kernel.org; Fri, 04 Jun 2021 13:18:09 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:53890) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lpCUi-0002dM-8T for qemu-devel@nongnu.org; Fri, 04 Jun 2021 12:16:24 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:38304) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lpCUg-0004V2-DI for qemu-devel@nongnu.org; Fri, 04 Jun 2021 12:16:24 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1622823381; 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: in-reply-to:in-reply-to:references:references; bh=kWtuOPfCoxheKsFFTC6tA0fBP0dhWlFcRqdB7yDlzoM=; b=e1heN6Wu+GskK1isL38MESqzv0UzgAQmMwEMw1jOWnocjcph5ym8TXY1mecvuQcqququad 14I7AS67LVY0zQNmmfG9tE6uQFRJMKETJP8kaRRsrZO0MwH84ukiubglvTuethJbEkURfc nK6ojPxjG1myK+mctEfMTdH7of+iL3g= 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-584-zjzXEzMLM62glVmNR36lsg-1; Fri, 04 Jun 2021 12:16:15 -0400 X-MC-Unique: zjzXEzMLM62glVmNR36lsg-1 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 B6276180FD6F; Fri, 4 Jun 2021 16:16:14 +0000 (UTC) Received: from redhat.com (ovpn-113-53.phx2.redhat.com [10.3.113.53]) by smtp.corp.redhat.com (Postfix) with ESMTPS id F04D061093; Fri, 4 Jun 2021 16:16:12 +0000 (UTC) Date: Fri, 4 Jun 2021 11:16:10 -0500 From: Eric Blake To: Emanuele Giuseppe Esposito Subject: Re: [PATCH v4 1/6] blkdebug: refactor removal of a suspended request Message-ID: <20210604161610.6we6yk2e77borfif@redhat.com> References: <20210604100741.18966-1-eesposit@redhat.com> <20210604100741.18966-2-eesposit@redhat.com> MIME-Version: 1.0 In-Reply-To: <20210604100741.18966-2-eesposit@redhat.com> User-Agent: NeoMutt/20210205 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eblake@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=170.10.133.124; envelope-from=eblake@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=-0.373, 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_H4=0.001, RCVD_IN_MSPIKE_WL=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 , Vladimir Sementsov-Ogievskiy , qemu-block@nongnu.org, qemu-devel@nongnu.org, Max Reitz , Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, Jun 04, 2021 at 12:07:36PM +0200, Emanuele Giuseppe Esposito wrote: > Extract to a separate function. Do not rely on FOREACH_SAFE, which is > only "safe" if the *current* node is removed---not if another node is > removed. Instead, just walk the entire list from the beginning when > asked to resume all suspended requests with a given tag. > > Co-developed-by: Paolo Bonzini > Signed-off-by: Emanuele Giuseppe Esposito > Reviewed-by: Vladimir Sementsov-Ogievskiy > --- > block/blkdebug.c | 28 +++++++++++++++++----------- > 1 file changed, 17 insertions(+), 11 deletions(-) > > diff --git a/block/blkdebug.c b/block/blkdebug.c > index 2c0b9b0ee8..8f19d991fa 100644 > --- a/block/blkdebug.c > -static int blkdebug_debug_resume(BlockDriverState *bs, const char *tag) > +static int resume_req_by_tag(BDRVBlkdebugState *s, const char *tag, bool all) > { > - BDRVBlkdebugState *s = bs->opaque; > - BlkdebugSuspendedReq *r, *next; > + BlkdebugSuspendedReq *r; > > - QLIST_FOREACH_SAFE(r, &s->suspended_reqs, next, next) { > +retry: > + QLIST_FOREACH(r, &s->suspended_reqs, next) { > if (!strcmp(r->tag, tag)) { > + QLIST_REMOVE(r, next); Isn't the whole point of using QLIST_FOREACH_SAFE the ability to call QLIST_REMOVE on an element in that list while still iterating? > qemu_coroutine_enter(r->co); > + if (all) { > + goto retry; > + } > return 0; Oh, I see - you abandon the iteration in all control flow paths, so the simpler loop is still okay. Still, this confused me enough on first read that it may be worth a comment, maybe: /* No need for _SAFE, because iteration stops on first hit */ Reviewed-by: Eric Blake -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org