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 400A9EFD216 for ; Wed, 25 Feb 2026 09:33:45 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vvBGa-0002BO-Rh; Wed, 25 Feb 2026 04:33:12 -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 1vvBGX-0002BB-EX for qemu-devel@nongnu.org; Wed, 25 Feb 2026 04:33:11 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vvBGP-0005BB-Tr for qemu-devel@nongnu.org; Wed, 25 Feb 2026 04:33:03 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1772011979; 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=fz7DUIMZhSyLpmz8iR9M49jdiPuZ5ipIS81yAb06D2s=; b=d9LFAFU2sOAl7XL2B3IP+1hLgC+vvd6KtgHM/3rM+rEVfW8NvhsxvEFkQqg2k7bubGVnNp 90saWP7ZxhbQ8aGTcIHhbbZv0lL+xmj4Lz1PvK2JOfMCJeohltBTx6cLC3aBX3K2cH4Mf2 mwpw41mXeFp8jbmnHp3rmtFi/fi2vH0= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-694-_rIOraWVMdGgjZ0TBded_w-1; Wed, 25 Feb 2026 04:32:55 -0500 X-MC-Unique: _rIOraWVMdGgjZ0TBded_w-1 X-Mimecast-MFC-AGG-ID: _rIOraWVMdGgjZ0TBded_w_1772011974 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 921D61800473; Wed, 25 Feb 2026 09:32:54 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.45.242.13]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 48F2A1800352; Wed, 25 Feb 2026 09:32:54 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id DAB4C21E692D; Wed, 25 Feb 2026 10:32:51 +0100 (CET) From: Markus Armbruster To: Daniel P. =?utf-8?Q?Berrang=C3=A9?= Cc: Prasad Pandit , Ani Sinha , Peter Xu , Fabiano Rosas , kraxel@redhat.com, pbonzini@redhat.com, ani@anisinha.ca, Prasad Pandit , qemu-devel@nongnu.org Subject: Re: [PATCH v6 35/35] migration: return EEXIST when trying to add the same migration blocker In-Reply-To: ("Daniel P. =?utf-8?Q?Berrang?= =?utf-8?Q?=C3=A9=22's?= message of "Wed, 25 Feb 2026 09:07:28 +0000") References: <20260225035000.385950-1-anisinha@redhat.com> <20260225035000.385950-36-anisinha@redhat.com> Date: Wed, 25 Feb 2026 10:32:51 +0100 Message-ID: <87342pw4l8.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -10 X-Spam_score: -1.1 X-Spam_bar: - X-Spam_report: (-1.1 / 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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.358, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.659, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development 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 Daniel P. Berrang=C3=A9 writes: > On Wed, Feb 25, 2026 at 11:35:15AM +0530, Prasad Pandit wrote: >> On Wed, 25 Feb 2026 at 09:23, Ani Sinha wrote: >> > Currently the code that adds a migration blocker does not check if the= same >> > blocker already exists. Return an EEXIST error code if there is an att= empt to >> > add the same migration blocker again. This way the same migration bloc= ker will >> > not get added twice. >> > >> > Suggested-by: Prasad Pandit >> > Signed-off-by: Ani Sinha >> > --- >> > migration/migration.c | 4 ++++ >> > 1 file changed, 4 insertions(+) >> > >> > diff --git a/migration/migration.c b/migration/migration.c >> > index a5b0465ed3..1eb75fb7fb 100644 >> > --- a/migration/migration.c >> > +++ b/migration/migration.c >> > @@ -1702,6 +1702,10 @@ static int add_blockers(Error **reasonp, unsign= ed modes, Error **errp) > > This method has an '**errp' parameter..... > >> > { >> > for (MigMode mode =3D 0; mode < MIG_MODE__MAX; mode++) { >> > if (modes & BIT(mode)) { >> > + if (g_slist_index(migration_blockers[mode], >> > + *reasonp) >=3D 0) { >> > + return -EEXIST; > > .... so using -errno for return values is not appropriate - it must > set 'errp' and return -1. Yes, it must set @errp on failure. Returning -1 would be wrong, because: int migrate_add_blocker_modes(Error **reasonp, unsigned modes, Error **= errp) { if (is_only_migratable(reasonp, modes, errp)) { return -EACCES; } else if (is_busy(reasonp, errp)) { return -EBUSY; } return add_blockers(reasonp, modes, errp); } If callers don't actually care for error codes, the entire nest of functions could be simplified to return 0/-1 or true/false. >> > + } >> > migration_blockers[mode] =3D g_slist_prepend(migration_bl= ockers[mode], >> > *reasonp); >> > } >>=20 >> * Looks okay. >> Reviewed-by: Prasad Pandit >>=20 >> Thank you. >> --- >> - Prasad >>=20 >>=20 > > With regards, > Daniel