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SubjectRe: [PATCH] IB/core: Make ib_mad_client_id atomic
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> 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

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