From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754258AbeD3Lv0 (ORCPT ); Mon, 30 Apr 2018 07:51:26 -0400 Received: from aserp2120.oracle.com ([141.146.126.78]:37050 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753414AbeD3LvX (ORCPT ); Mon, 30 Apr 2018 07:51:23 -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: <1524856116.11756.85.camel@redhat.com> Date: Mon, 30 Apr 2018 13:50:57 +0200 Cc: jackm , Jason Gunthorpe , Don Hiatt , Ira Weiny , Sean Hefty , OFED mailing list , linux-kernel@vger.kernel.org Message-Id: 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> <20180426213250.0000515d@dev.mellanox.co.il> <9fdd3ec4-ee91-5442-e753-25d2ecd27ea9@xsintricity.com> <1524856116.11756.85.camel@redhat.com> To: Doug Ledford X-Mailer: Apple Mail (2.3445.6.18) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8878 signatures=668698 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=3 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=965 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1711220000 definitions=main-1804300115 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 w3UBpVBs019350 > On 27 Apr 2018, at 21:08, Doug Ledford wrote: > > On Thu, 2018-04-26 at 20:51 +0200, Håkon Bugge wrote: >>> Jason is out this week. I'll end up processing this one (probably later >>> today). But I’ll fix up the commit message to suit my tastes when I do. >> >> Thank you, Doug and Jack, > > I reworded the commit message, let me know if you think I worded it > wrong: > > commit 69f01b81539c62f3dd96f9f02138ad7b839a0c70 (HEAD -> k.o/wip/dl-for-rc) > Author: Håkon Bugge > Date: Wed Apr 18 16:24:50 2018 +0200 > > IB/core: Make ib_mad_client_id atomic > > Currently, 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: "Then initiating > a new operation, MADHeader:TransactionID shall be set to such a value > that within that MAD the combination of TIG, SGID, and MgmtClass is > different from that of any other currently executing operation. If the > MAD does not have a GRH, its SLID is used in the combination in place of > an SGID." which guarantees we are legal because our different ports will > have different SGID/SLID creating a unique tuple even if the TIDs are > identical), and as we might want to open the TID allocator up to more > parallel usage later, make the TID an atomic type so that no two > allocations, regardless of port number, will be the same. The wording is OK per se, but the last sentence spans 12 lines - and as such - a little bit hard to comprehend. I suggest just to refer to IB Spec 1.3, clause C13-18.1.1 and not quote it and make the last sub-sentence (starting with “and as we might want to open”) a sentence by its own. Thxs, Håkon > > Signed-off-by: Håkon Bugge > Reviewed-by: Jack Morgenstein > Reviewed-by: Ira Weiny > Reviewed-by: Zhu Yanjun > Signed-off-by: Doug Ledford > > -- > Doug Ledford > GPG KeyID: B826A3330E572FDD > Key fingerprint = AE6B 1BDA 122B 23B4 265B 1274 B826 A333 0E57 2FDD