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From: "Håkon Bugge" <haakon.bugge@oracle.com>
To: Doug Ledford <dledford@redhat.com>
Cc: jackm <jackm@dev.mellanox.co.il>, Jason Gunthorpe <jgg@ziepe.ca>,
	Don Hiatt <don.hiatt@intel.com>, Ira Weiny <ira.weiny@intel.com>,
	Sean Hefty <sean.hefty@intel.com>,
	OFED mailing list <linux-rdma@vger.kernel.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] IB/core: Make ib_mad_client_id atomic
Date: Mon, 30 Apr 2018 13:50:57 +0200	[thread overview]
Message-ID: <DCABB189-F45C-487C-A78F-2F8441928E4B@oracle.com> (raw)
In-Reply-To: <1524856116.11756.85.camel@redhat.com>



> On 27 Apr 2018, at 21:08, Doug Ledford <dledford@redhat.com> 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 <haakon.bugge@oracle.com>
> 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 <haakon.bugge@oracle.com>
>    Reviewed-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
>    Reviewed-by: Ira Weiny <ira.weiny@intel.com>
>    Reviewed-by: Zhu Yanjun <yanjun.zhu@oracle.com>
>    Signed-off-by: Doug Ledford <dledford@redhat.com>
> 
> -- 
> Doug Ledford <dledford@redhat.com>
>    GPG KeyID: B826A3330E572FDD
>    Key fingerprint = AE6B 1BDA 122B 23B4 265B  1274 B826 A333 0E57 2FDD

  reply	other threads:[~2018-04-30 11:51 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-18 14:24 Håkon Bugge
2018-04-18 18:51 ` Weiny, Ira
2018-04-19  2:59 ` Yanjun Zhu
2018-04-20  3:55 ` Doug Ledford
2018-04-20 15:34   ` Jason Gunthorpe
2018-04-23 14:19     ` Håkon Bugge
2018-04-23 19:16       ` jackm
2018-04-26 16:06         ` Håkon Bugge
2018-04-26 18:32           ` jackm
     [not found]             ` <9fdd3ec4-ee91-5442-e753-25d2ecd27ea9@xsintricity.com>
     [not found]               ` <A58D5192-06E7-46A3-869C-273E9A2BC128@oracle.com>
2018-04-27 19:08                 ` Doug Ledford
2018-04-30 11:50                   ` Håkon Bugge [this message]
2018-04-30 14:49         ` Jason Gunthorpe
2018-04-30 17:10           ` Doug Ledford
2018-04-30 17:49             ` Weiny, Ira
2018-04-30 23:01             ` Jason Gunthorpe
2018-05-01  4:38             ` jackm
2018-05-01  6:40               ` Håkon Bugge

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