linux-kernel - Re: [RFC PATCH 07/11] IB/Verbs: Use management helper has_mcast() and, cap

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Message-ID: <551909AC.2030304@profitbricks.com>
Date:	Mon, 30 Mar 2015 10:30:36 +0200
From:	Michael Wang <yun.wang@...fitbricks.com>
To:	Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
	"ira.weiny" <ira.weiny@...el.com>
CC:	Roland Dreier <roland@...nel.org>,
	Sean Hefty <sean.hefty@...el.com>,
	Hal Rosenstock <hal.rosenstock@...il.com>,
	linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-nfs@...r.kernel.org, netdev@...r.kernel.org,
	"J. Bruce Fields" <bfields@...ldses.org>,
	Trond Myklebust <trond.myklebust@...marydata.com>,
	"David S. Miller" <davem@...emloft.net>,
	Or Gerlitz <ogerlitz@...lanox.com>,
	Moni Shoua <monis@...lanox.com>,
	PJ Waskiewicz <pj.waskiewicz@...idfire.com>,
	Tatyana Nikolova <Tatyana.E.Nikolova@...el.com>,
	Yan Burman <yanb@...lanox.com>,
	Jack Morgenstein <jackm@....mellanox.co.il>,
	Bart Van Assche <bvanassche@....org>,
	Yann Droneaud <ydroneaud@...eya.com>,
	Colin Ian King <colin.king@...onical.com>,
	Majd Dibbiny <majd@...lanox.com>,
	Jiri Kosina <jkosina@...e.cz>,
	Matan Barak <matanb@...lanox.com>,
	Alex Estrin <alex.estrin@...el.com>,
	Doug Ledford <dledford@...hat.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Erez Shitrit <erezsh@...lanox.com>,
	Sagi Grimberg <sagig@...lanox.com>,
	Haggai Eran <haggaie@...lanox.com>,
	Shachar Raindel <raindel@...lanox.com>,
	Mike Marciniszyn <mike.marciniszyn@...el.com>,
	Steve Wise <swise@...ngridcomputing.com>,
	Tom Tucker <tom@....us>, Chuck Lever <chuck.lever@...cle.com>
Subject: Re: [RFC PATCH 07/11] IB/Verbs: Use management helper has_mcast()
 and, cap_mcast() for mcast-check



On 03/27/2015 06:47 PM, Jason Gunthorpe wrote:
> On Fri, Mar 27, 2015 at 01:05:08PM -0400, ira.weiny wrote:
>
>>> But it seems redudent, since mcast_add_one will already not add a port that is
>>> not IB, so mcast_event_handler is not callable. Something to do with
>>> rocee/ib switching?
>> I'm not sure about this either.  This check seems to be necessary only on a
>> per-port level.  It does seem apparent that one can't go from Eth to IB.  What
>> happens if you go from IB to Eth on the port?
> Hmm... I see a mlx4_change_port_types which ultimately calls
> ib_unregister_device, which suggests the port type doesn't change at
> runtime (yay)
Yeah, seems like mlx4 will reinitialize the device when port link layer
changed.

I've take a look at other HW, they directly return a static type or
infer from transport type (I suppose this won't change dynamically).

Thus I also agreed check inside mcast_event_handler() is unnecessary,
maybe we can change that logical to WARN_ON(!cap_mcast()) ?

Regards,
Michael Wang

>
> So maybe these checks really are redundant?
>
> Jason

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