From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751928AbeEAGkg (ORCPT ); Tue, 1 May 2018 02:40:36 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:41760 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751011AbeEAGkf (ORCPT ); Tue, 1 May 2018 02:40:35 -0400 Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 11.3 \(3445.6.18\)) Subject: Re: [PATCH] IB/core: Make ib_mad_client_id atomic From: =?utf-8?Q?H=C3=A5kon_Bugge?= In-Reply-To: <20180501073816.00001ec6@dev.mellanox.co.il> Date: Tue, 1 May 2018 08:40:07 +0200 Cc: Doug Ledford , Jason Gunthorpe , Don Hiatt , Dasaratharaman Chandramouli , Ira Weiny , Sean Hefty , OFED mailing list , linux-kernel@vger.kernel.org Message-Id: <451F533C-60E1-4154-9540-92CB83276446@oracle.com> References: <20180418142450.15581-1-Haakon.Bugge@oracle.com> <1524196555.11756.30.camel@redhat.com> <20180420153451.GF30433@ziepe.ca> <50E3FE4A-2C6E-4493-92E1-383C349FAE3A@oracle.com> <20180423221618.0000795d@dev.mellanox.co.il> <20180430144930.GB26895@ziepe.ca> <1525108249.11756.93.camel@redhat.com> <20180501073816.00001ec6@dev.mellanox.co.il> To: jackm X-Mailer: Apple Mail (2.3445.6.18) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8879 signatures=668698 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=15 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=862 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1711220000 definitions=main-1805010067 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id w416ekS3014750 > On 1 May 2018, at 06:38, jackm wrote: > > On Mon, 30 Apr 2018 13:10:49 -0400 > Doug Ledford wrote: > > Looks good! Yes, absolutely! Håkon > > -Jack > >> On Mon, 2018-04-30 at 08:49 -0600, Jason Gunthorpe wrote: >>> On Mon, Apr 23, 2018 at 10:16:18PM +0300, jackm wrote: >>> >>>>>> TIDs need to be globally unique on the entire machine. >>>> Jason, that is not exactly correct. >>> >>> The expecation for /dev/umad users is that they all receive locally >>> unique TID prefixes. The kernel may be OK to keep things >>> port-specific but it is slightly breaking the API we are presenting >>> to userspace to allow them to alias.. >>> >>> Jason >> >> Would people be happier with this commit message then: >> >> IB/core: Make ib_mad_client_id atomic >> >> Currently, the kernel protects access to the agent ID allocator on a >> per port basis using a spinlock, so it is impossible for two >> apps/threads on the same port to get the same TID, but it is entirely >> possible for two threads on different ports to end up with the same >> TID. >> >> As this can be confusing (regardless of it being legal according to >> the IB Spec 1.3, C13-18.1.1, in section 13.4.6.4 - TransactionID >> usage), and as the rdma-core user space API for /dev/umad devices >> implies unique TIDs even across ports, make the TID an atomic type so >> that no two allocations, regardless of port number, will be the same. >> >> Signed-off-by: Håkon Bugge >> Reviewed-by: Jack Morgenstein >> Reviewed-by: Ira Weiny >> Reviewed-by: Zhu Yanjun >> Signed-off-by: Doug Ledford >> >> > > -- > To unsubscribe from this list: send the line "unsubscribe linux-rdma" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html