From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by sourceware.org (Postfix) with ESMTPS id 6C2C13858D3C for ; Mon, 24 Jan 2022 12:38:31 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 6C2C13858D3C Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-151-ULMIQ6CJOleUK_jG2uEOvw-1; Mon, 24 Jan 2022 07:38:29 -0500 X-MC-Unique: ULMIQ6CJOleUK_jG2uEOvw-1 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 7F9F310055B3; Mon, 24 Jan 2022 12:38:28 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.192.8]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A7710753EE; Mon, 24 Jan 2022 12:38:27 +0000 (UTC) From: Florian Weimer To: Adhemerval Zanella Cc: Adhemerval Zanella via Libc-alpha Subject: Re: [PATCH v4] linux: Fix ancillary 64-bit time timestamp conversion (BZ #28349, BZ #28350) References: <20211222185239.1088511-1-adhemerval.zanella@linaro.org> <8735lh6vqo.fsf@oldenburg.str.redhat.com> <372ae1ee-0163-7bf4-be1c-cc1f13b1a940@linaro.org> <87bl0149i2.fsf@oldenburg.str.redhat.com> <9263a5c2-48c4-a5d1-c159-2f0ee4e26c52@linaro.org> Date: Mon, 24 Jan 2022 13:38:25 +0100 In-Reply-To: <9263a5c2-48c4-a5d1-c159-2f0ee4e26c52@linaro.org> (Adhemerval Zanella's message of "Mon, 24 Jan 2022 09:23:04 -0300") Message-ID: <87y2352try.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-6.2 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 24 Jan 2022 12:38:32 -0000 * Adhemerval Zanella: > On 24/01/2022 09:13, Florian Weimer wrote: >> * Adhemerval Zanella: >> >>>> typo: MSG_[C]TRUNC >>>> >>>> (I think this MSG_CTRUNC result is a remaining bug we need to fix >>>> separately for time32 mode.) >>> >>> Do you mean not returning the MSG_CTRUNC? >> >> No, if the caller uses CMSG_SPACE to allocate space for the expected >> ancillary data, we should not produce MSG_CTRUNC by stuffing in >> ancillary data that has not been requested. Maybe we can do this for >> time32 code only. Again it seems that userspace emulation is rather >> questionable here. > > But this would be only an issue for applications using _TIME_BITS=64 > running on older kernels (so 32 bit timestamps would be visible to > the caller). Since 64 bit is a opt-in feature, I think users will > see way more potential issues running _TIME_BITS=64 on older kernels. As far as I can see, it is currently an issue for time32 applications running on old and new kernels. We synthesize the time64 control messages unconditionally. Thanks, Florian