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 BEDA9C433FE for ; Wed, 9 Nov 2022 21:49:37 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1osswg-0003kd-Dg; Wed, 09 Nov 2022 16:49:18 -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 1osswf-0003kS-AX for qemu-devel@nongnu.org; Wed, 09 Nov 2022 16:49:17 -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 1osswd-0006qJ-SV for qemu-devel@nongnu.org; Wed, 09 Nov 2022 16:49:17 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1668030555; 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=VpL+Wzx7TM88XtFF9JL9J0HhCorMq1GdbyU9eyA3l+g=; b=BQ6EX7dlgsNkhGvwgz1IeBnhHuKWgoy1QmJRHZV9RuftWlJYM1dlAWFfSHkDfswMvYkzcJ 905LDhpM2/Yujw9h68KHv8jihEN5mN6376uxO2QTQ489DPWorhvv+ADBRCrwQ+ObrXPKGH cIt+sfRWhwaBEP9jDmaQRyuzlICtGK0= 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-45-kMsJeJYyOZG0HCe4Nvf3_Q-1; Wed, 09 Nov 2022 16:49:13 -0500 X-MC-Unique: kMsJeJYyOZG0HCe4Nvf3_Q-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id B905A185A79C; Wed, 9 Nov 2022 21:49:12 +0000 (UTC) Received: from localhost (unknown [10.39.192.85]) by smtp.corp.redhat.com (Postfix) with ESMTP id 38F7D10197; Wed, 9 Nov 2022 21:49:11 +0000 (UTC) Date: Wed, 9 Nov 2022 16:49:10 -0500 From: Stefan Hajnoczi To: Kevin Wolf Cc: qemu-block@nongnu.org, eesposit@redhat.com, hreitz@redhat.com, pbonzini@redhat.com, qemu-devel@nongnu.org Subject: Re: [PATCH 01/13] qed: Don't yield in bdrv_qed_co_drain_begin() Message-ID: References: <20221108123738.530873-1-kwolf@redhat.com> <20221108123738.530873-2-kwolf@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="qvAZ+4uu9lqm8OpO" Content-Disposition: inline In-Reply-To: <20221108123738.530873-2-kwolf@redhat.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 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=ham 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 --qvAZ+4uu9lqm8OpO Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Nov 08, 2022 at 01:37:26PM +0100, Kevin Wolf wrote: > @@ -310,9 +309,20 @@ static void coroutine_fn qed_need_check_timer_entry(= void *opaque) > (void) ret; > } > =20 > +static void coroutine_fn qed_need_check_timer_entry(void *opaque) > +{ > + BDRVQEDState *s =3D opaque; > + > + qed_need_check_timer(opaque); > + bdrv_dec_in_flight(s->bs); > +} > + > static void qed_need_check_timer_cb(void *opaque) > { > + BDRVQEDState *s =3D opaque; > Coroutine *co =3D qemu_coroutine_create(qed_need_check_timer_entry, = opaque); > + > + bdrv_inc_in_flight(s->bs); > qemu_coroutine_enter(co); > } > =20 > @@ -363,8 +373,12 @@ static void coroutine_fn bdrv_qed_co_drain_begin(Blo= ckDriverState *bs) > * header is flushed. > */ > if (s->need_check_timer && timer_pending(s->need_check_timer)) { > + Coroutine *co; > + > qed_cancel_need_check_timer(s); > - qed_need_check_timer_entry(s); > + co =3D qemu_coroutine_create(qed_need_check_timer_entry, s); > + bdrv_inc_in_flight(bs); Please include comments that indicate where inc/dec are paired. This is like pairing memory barriers where it can be very hard to know after the code has been written (and modified). --qvAZ+4uu9lqm8OpO Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAmNsIFYACgkQnKSrs4Gr c8is5gf+Ox92mFis7Unns1KVpBkl0ZC6NtUL+HFLrhO8RkDw8XbNiSVjOm4cO3/w UiZPRgUPV9nnHvyNyHM2a5iaV5SZCLG57WX3buZgHY5fumyUVUvXza6xt2ZrXjhH 5ohm9o7fmBwhhgEzRRkkp+fZCbIIYeL+SJbU+OxW8KrB17J9I0kVJqh33A1Tg4ry 8DytccThZmtxK0FLU1lcOVOCr+NwmnqfafXlDNZ5wOPZ6sWw/AJAqxPa4lX/uBoq 21P+PFFw5u6I7z9XHnDBvhZbqVnabJuxwLOG1Fr+845YQMCg1qb2tvVwyO2JErCE 9ERufestV7na6kFcrnQdAHw+ssv0Ug== =gn4t -----END PGP SIGNATURE----- --qvAZ+4uu9lqm8OpO--